OpenLDAP Software 2.6 Administrator's Guide
===========================================

The OpenLDAP Project <https://www.openldap.org/>


Preface
=======

Copyright
---------

Copyright 1998-2013, The OpenLDAP Foundation, All Rights Reserved.

Copyright 1992-1996, Regents of the University of Michigan, All Rights
Reserved.

This document is considered a part of OpenLDAP Software.  This
document is subject to terms of conditions set forth in OpenLDAP
Software Copyright Notices and the OpenLDAP Public License. Complete
copies of the notices and associated license can be found in Appendix
K and L, respectively.

Portions of OpenLDAP Software and this document may be copyright by
other parties and/or subject to additional restrictions.  Individual
source files should be consulted for additional copyright notices.

Scope of this Document
----------------------

This document provides a guide for installing OpenLDAP Software 2.6
(http://www.openldap.org/software/) on UNIX (and UNIX-like) systems. 
The document is aimed at experienced system administrators with basic
understanding of LDAP-based directory services.

This document is meant to be used in conjunction with other OpenLDAP
information resources provided with the software package and on the
project's site (http://www.OpenLDAP.org/) on the World Wide Web.  The
site makes available a number of resources.

OpenLDAP Resources

Resource                           URL
.................................. .................................. 
Document Catalog                   http://www.OpenLDAP.org/doc/
Frequently Asked Questions         http://www.OpenLDAP.org/faq/
Issue Tracking System              http://www.OpenLDAP.org/its/
Mailing Lists                      http://www.OpenLDAP.org/lists/
Manual Pages                       http://www.OpenLDAP.org/software/man.cgi
Software Pages                     http://www.OpenLDAP.org/software/
Support Pages                      http://www.OpenLDAP.org/support/

This document is not a complete reference for OpenLDAP software; the
manual pages are the definitive documentation. For best results, you
should use the manual pages that were installed on your system with
your version of OpenLDAP software so that you're looking at
documentation that matches the code. While the OpenLDAP web site also
provides the manual pages for convenience, you can not assume that
they correspond to the particular version you're running.

Acknowledgments
---------------

The OpenLDAP Project is comprised of a team of volunteers.  This
document would not be possible without their contribution of time and
energy.

The OpenLDAP Project would also like to thank the University of
Michigan LDAP Team for building the foundation of LDAP software and
information to which OpenLDAP Software is built upon.  This document
is based upon University of Michigan document: The SLAPD and SLURPD
Administrators Guide.

Amendments
----------

Suggested enhancements and corrections to this document should be
submitted using the OpenLDAP Issue Tracking System
(http://www.openldap.org/its/).

About this document
-------------------

This document was produced using the Simple Document Format (SDF)
documentation system
(http://search.cpan.org/src/IANC/sdf-2.001/doc/catalog.html) developed
by Ian Clatworthy.  Tools for SDF are available from CPAN
(http://search.cpan.org/search?query=SDF&mode=dist).


1. Introduction to OpenLDAP Directory Services
==============================================

This document describes how to build, configure, and operate OpenLDAP
Software to provide directory services.  This includes details on how
to configure and run the Standalone LDAP Daemon, slapd(8).  It is
intended for new and experienced administrators alike.  This section
provides a basic introduction to directory services and, in
particular, the directory services provided by slapd(8).  This
introduction is only intended to provide enough information so one
might get started learning about LDAP, X.500, and directory services.

1.1. What is a directory service?
---------------------------------

A directory is a specialized database specifically designed for
searching and browsing, in additional to supporting basic lookup and
update functions.

Note: A directory is defined by some as merely a database optimized
for read access.  This definition, at best, is overly simplistic.

Directories tend to contain descriptive, attribute-based information
and support sophisticated filtering capabilities.  Directories
generally do not support complicated transaction or roll-back schemes
found in database management systems designed for handling high-volume
complex updates.  Directory updates are typically simple
all-or-nothing changes, if they are allowed at all.  Directories are
generally tuned to give quick response to high-volume lookup or search
operations. They may have the ability to replicate information widely
in order to increase availability and reliability, while reducing
response time.  When directory information is replicated, temporary
inconsistencies between the consumers may be okay, as long as
inconsistencies are resolved in a timely manner.

There are many different ways to provide a directory service.
Different methods allow different kinds of information to be stored in
the directory, place different requirements on how that information
can be referenced, queried and updated, how it is protected from
unauthorized access, etc.  Some directory services are local,
providing service to a restricted context (e.g., the finger service on
a single machine). Other services are global, providing service to a
much broader context (e.g., the entire Internet).  Global services are
usually distributed, meaning that the data they contain is spread
across many machines, all of which cooperate to provide the directory
service. Typically a global service defines a uniform namespace which
gives the same view of the data no matter where you are in relation to
the data itself.

A web directory, such as provided by the Curlie Project
<https://curlie.org>, is a good example of a directory service. These
services catalog web pages and are specifically designed to support
browsing and searching.

While some consider the Internet Domain Name System (DNS) is an
example of a globally distributed directory service, DNS is not
browsable nor searchable.  It is more properly described as a globally
distributed lookup service.

1.2. What is LDAP?
------------------

LDAP stands for Lightweight Directory Access Protocol.  As the name
suggests, it is a lightweight protocol for accessing directory
services, specifically X.500-based directory services.  LDAP runs over
TCP/IP or other connection oriented transfer services.  LDAP is an
IETF Standard Track protocol and is specified in "Lightweight
Directory Access Protocol (LDAP) Technical Specification Road Map"
RFC4510.

This section gives an overview of LDAP from a user's perspective.

What kind of information can be stored in the directory? The LDAP
information model is based on entries. An entry is a collection of
attributes that has a globally-unique Distinguished Name (DN).  The DN
is used to refer to the entry unambiguously. Each of the entry's
attributes has a type and one or more values. The types are typically
mnemonic strings, like "cn" for common name, or "mail" for email
address. The syntax of values depend on the attribute type.  For
example, a cn attribute might contain the value Babs Jensen.  A mail
attribute might contain the value "babs@example.com". A jpegPhoto
attribute would contain a photograph in the JPEG (binary) format.

How is the information arranged? In LDAP, directory entries are
arranged in a hierarchical tree-like structure.  Traditionally, this
structure reflected the geographic and/or organizational boundaries. 
Entries representing countries appear at the top of the tree. Below
them are entries representing states and national organizations. Below
them might be entries representing organizational units, people,
printers, documents, or just about anything else you can think of. 
Figure 1.1 shows an example LDAP directory tree using traditional
naming.

** Unable to import figure intro_tree.png **

Figure 1.1: LDAP directory tree (traditional naming)

The tree may also be arranged based upon Internet domain names. This
naming approach is becoming increasing popular as it allows for
directory services to be located using the DNS. Figure 1.2 shows an
example LDAP directory tree using domain-based naming.

** Unable to import figure intro_dctree.png **

Figure 1.2: LDAP directory tree (Internet naming)

In addition, LDAP allows you to control which attributes are required
and allowed in an entry through the use of a special attribute called
objectClass.  The values of the objectClass attribute determine the
schema rules the entry must obey.

How is the information referenced? An entry is referenced by its
distinguished name, which is constructed by taking the name of the
entry itself (called the Relative Distinguished Name or RDN) and
concatenating the names of its ancestor entries. For example, the
entry for Barbara Jensen in the Internet naming example above has an
RDN of uid=babs and a DN of uid=babs,ou=People,dc=example,dc=com. The
full DN format is described in RFC4514, "LDAP: String Representation
of Distinguished Names."

How is the information accessed? LDAP defines operations for
interrogating and updating the directory.  Operations are provided for
adding and deleting an entry from the directory, changing an existing
entry, and changing the name of an entry. Most of the time, though,
LDAP is used to search for information in the directory. The LDAP
search operation allows some portion of the directory to be searched
for entries that match some criteria specified by a search filter.
Information can be requested from each entry that matches the
criteria.

For example, you might want to search the entire directory subtree at
and below dc=example,dc=com for people with the name Barbara Jensen,
retrieving the email address of each entry found. LDAP lets you do
this easily.  Or you might want to search the entries directly below
the st=California,c=US entry for organizations with the string Acme in
their name, and that have a fax number. LDAP lets you do this too. The
next section describes in more detail what you can do with LDAP and
how it might be useful to you.

How is the information protected from unauthorized access? Some
directory services provide no protection, allowing anyone to see the
information. LDAP provides a mechanism for a client to authenticate,
or prove its identity to a directory server, paving the way for rich
access control to protect the information the server contains. LDAP
also supports data security (integrity and confidentiality) services.

1.3. When should I use LDAP?
----------------------------

This is a very good question. In general, you should use a Directory
server when you require data to be centrally managed, stored and
accessible via standards based methods.

Some common examples found throughout the industry are, but not
limited to:

o    Machine Authentication

o    User Authentication

o    User/System Groups

o    Address book

o    Organization Representation

o    Asset Tracking

o    Telephony Information Store

o    User resource management

o    E-mail address lookups

o    Application Configuration store

o    PBX Configuration store

o    etc.....

There are various Distributed Schema Files that are standards based,
but you can always create your own Schema Specification.

There are always new ways to use a Directory and apply LDAP principles
to address certain problems, therefore there is no simple answer to
this question.

If in doubt, join the general LDAP forum for non-commercial
discussions and information relating to LDAP at:
http://www.umich.edu/~dirsvcs/ldap/mailinglist.html and ask

1.4. When should I not use LDAP?
--------------------------------

When you start finding yourself bending the directory to do what you
require, maybe a redesign is needed. Or if you only require one
application to use and manipulate your data (for discussion of LDAP vs
RDBMS, please read the LDAP vs RDBMS section).

It will become obvious when LDAP is the right tool for the job.

1.5. How does LDAP work?
------------------------

LDAP utilizes a client-server model. One or more LDAP servers contain
the data making up the directory information tree (DIT). The client
connects to servers and asks it a question.  The server responds with
an answer and/or with a pointer to where the client can get additional
information (typically, another LDAP server). No matter which LDAP
server a client connects to, it sees the same view of the directory; a
name presented to one LDAP server references the same entry it would
at another LDAP server.  This is an important feature of a global
directory service.

1.6. What about X.500?
----------------------

Technically, LDAP is a directory access protocol to an X.500 directory
service, the OSI directory service. Initially, LDAP clients accessed
gateways to the X.500 directory service. This gateway ran LDAP between
the client and gateway and X.500's Directory Access Protocol (DAP)
between the gateway and the X.500 server.  DAP is a heavyweight
protocol that operates over a full OSI protocol stack and requires a
significant amount of computing resources.  LDAP is designed to
operate over TCP/IP and provides most of the functionality of DAP at a
much lower cost.

While LDAP is still used to access X.500 directory service via
gateways, LDAP is now more commonly directly implemented in X.500
servers.

The Standalone LDAP Daemon, or slapd(8), can be viewed as a
lightweight X.500 directory server.  That is, it does not implement
the X.500's DAP nor does it support the complete X.500 models.

If you are already running a X.500 DAP service and you want to
continue to do so, you can probably stop reading this guide.  This
guide is all about running LDAP via slapd(8), without running X.500
DAP.  If you are not running X.500 DAP, want to stop running X.500
DAP, or have no immediate plans to run X.500 DAP, read on.

It is possible to replicate data from an LDAP directory server to a
X.500 DAP DSA.  This requires an LDAP/DAP gateway. OpenLDAP Software
does not include such a gateway.

1.7. What is the difference between LDAPv2 and LDAPv3?
------------------------------------------------------

LDAPv3 was developed in the late 1990's to replace LDAPv2. LDAPv3 adds
the following features to LDAP:

o    Strong authentication and data security services via SASL

o    Certificate authentication and data security services via TLS
     (SSL)

o    Internationalization through the use of Unicode

o    Referrals and Continuations

o    Schema Discovery

o    Extensibility (controls, extended operations, and more)

LDAPv2 is historic (RFC3494).  As most so-called LDAPv2
implementations (including slapd(8)) do not conform to the LDAPv2
technical specification, interoperability amongst implementations
claiming LDAPv2 support is limited.  As LDAPv2 differs significantly
from LDAPv3, deploying both LDAPv2 and LDAPv3 simultaneously is quite
problematic.  LDAPv2 should be avoided. LDAPv2 is disabled by default.

1.8. LDAP vs RDBMS
------------------

This question is raised many times, in different forms. The most
common, however, is: Why doesn't OpenLDAP use a relational database
management system (RDBMS) instead of an embedded key/value store like
LMDB? In general, expecting that the sophisticated algorithms
implemented by commercial-grade RDBMS would make OpenLDAP be faster or
somehow better and, at the same time, permitting sharing of data with
other applications.

The short answer is that use of an embedded database and custom
indexing system allows OpenLDAP to provide greater performance and
scalability without loss of reliability. OpenLDAP uses LMDB concurrent
/ transactional database software.

Now for the long answer. We are all confronted all the time with the
choice RDBMSes vs. directories. It is a hard choice and no simple
answer exists.

It is tempting to think that having a RDBMS backend to the directory
solves all problems. However, it is a pig. This is because the data
models are very different. Representing directory data with a
relational database is going to require splitting data into multiple
tables.

Think for a moment about the person objectclass. Its definition
requires attribute types objectclass, sn and cn and allows attribute
types userPassword, telephoneNumber, seeAlso and description. All of
these attributes are multivalued, so a normalization requires putting
each attribute type in a separate table.

Now you have to decide on appropriate keys for those tables. The
primary key might be a combination of the DN, but this becomes rather
inefficient on most database implementations.

The big problem now is that accessing data from one entry requires
seeking on different disk areas. On some applications this may be OK
but in many applications performance suffers.

The only attribute types that can be put in the main table entry are
those that are mandatory and single-value. You may add also the
optional single-valued attributes and set them to NULL or something if
not present.

But wait, the entry can have multiple objectclasses and they are
organized in an inheritance hierarchy. An entry of objectclass
organizationalPerson now has the attributes from person plus a few
others and some formerly optional attribute types are now mandatory.

What to do? Should we have different tables for the different
objectclasses? This way the person would have an entry on the person
table, another on organizationalPerson, etc. Or should we get rid of
person and put everything on the second table?

But what do we do with a filter like (cn=*) where cn is an attribute
type that appears in many, many objectclasses. Should we search all
possible tables for matching entries? Not very attractive.

Once this point is reached, three approaches come to mind. One is to
do full normalization so that each attribute type, no matter what, has
its own separate table. The simplistic approach where the DN is part
of the primary key is extremely wasteful, and calls for an approach
where the entry has a unique numeric id that is used instead for the
keys and a main table that maps DNs to ids. The approach, anyway, is
very inefficient when several attribute types from one or more entries
are requested. Such a database, though cumbersomely, can be managed
from SQL applications.

The second approach is to put the whole entry as a blob in a table
shared by all entries regardless of the objectclass and have
additional tables that act as indices for the first table. Index
tables are not database indices, but are fully managed by the LDAP
server-side implementation. However, the database becomes unusable
from SQL. And, thus, a fully fledged database system provides little
or no advantage. The full generality of the database is unneeded. Much
better to use something light and fast, like LMDB.

A completely different way to see this is to give up any hopes of
implementing the directory data model. In this case, LDAP is used as
an access protocol to data that provides only superficially the
directory data model. For instance, it may be read only or, where
updates are allowed, restrictions are applied, such as making
single-value attribute types that would allow for multiple values. Or
the impossibility to add new objectclasses to an existing entry or
remove one of those present. The restrictions span the range from
allowed restrictions (that might be elsewhere the result of access
control) to outright violations of the data model. It can be, however,
a method to provide LDAP access to preexisting data that is used by
other applications. But in the understanding that we don't really have
a "directory".

Existing commercial LDAP server implementations that use a relational
database are either from the first kind or the third. I don't know of
any implementation that uses a relational database to do inefficiently
what LMDB does efficiently. For those who are interested in "third
way" (exposing EXISTING data from RDBMS as LDAP tree, having some
limitations compared to classic LDAP model, but making it possible to
interoperate between LDAP and SQL applications):

OpenLDAP includes back-sql - the backend that makes it possible. It
uses ODBC + additional metainformation about translating LDAP queries
to SQL queries in your RDBMS schema, providing different levels of
access - from read-only to full access depending on RDBMS you use, and
your schema.

For more information on concept and limitations, see slapd-sql(5) man
page, or the Backends section. There are also several examples for
several RDBMSes in back-sql/rdbms_depend/* subdirectories.

1.9. What is slapd and what can it do?
--------------------------------------

slapd(8) is an LDAP directory server that runs on many different
platforms. You can use it to provide a directory service of your very
own.  Your directory can contain pretty much anything you want to put
in it. You can connect it to the global LDAP directory service, or run
a service all by yourself. Some of slapd's more interesting features
and capabilities include:

LDAPv3: slapd implements version 3 of Lightweight Directory Access
Protocol. slapd supports LDAP over both IPv4 and IPv6 and Unix IPC.

Simple Authentication and Security Layer: slapd supports strong
authentication and data security (integrity and confidentiality)
services through the use of SASL.  slapd's SASL implementation
utilizes Cyrus SASL software which supports a number of mechanisms
including DIGEST-MD5, EXTERNAL, and GSSAPI.

Transport Layer Security: slapd supports certificate-based
authentication and data security (integrity and confidentiality)
services through the use of TLS (or SSL).  slapd's TLS implementation
can utilize OpenSSL or GnuTLS, software.

Topology control: slapd can be configured to restrict access at the
socket layer based upon network topology information. This feature
utilizes TCP wrappers.

Access control: slapd provides a rich and powerful access control
facility, allowing you to control access to the information in your
database(s). You can control access to entries based on LDAP
authorization information, IP address, domain name and other criteria.
 slapd supports both static and dynamic access control information.

Internationalization: slapd supports Unicode and language tags.

Choice of database backends: slapd comes with a variety of different
database backends you can choose from. They include MDB, a
hierarchical high-performance transactional database backend; and
PASSWD, a simple backend interface to the passwd(5) file. The MDB
backend utilizes LMDB.

Multiple database instances: slapd can be configured to serve multiple
databases at the same time. This means that a single slapd server can
respond to requests for many logically different portions of the LDAP
tree, using the same or different database backends.

Generic modules API:  If you require even more customization, slapd
lets you write your own modules easily. slapd consists of two distinct
parts: a front end that handles protocol communication with LDAP
clients; and modules which handle specific tasks such as database
operations.  Because these two pieces communicate via a well-defined C
API, you can write your own customized modules which extend slapd in
numerous ways.  Also, a number of programmable database modules are
provided.  These allow you to expose external data sources to slapd
using popular programming languages (Perl, and SQL).

Threads: slapd is threaded for high performance.  A single
multi-threaded slapd process handles all incoming requests using a
pool of threads.  This reduces the amount of system overhead required
while providing high performance.

Replication: slapd can be configured to maintain shadow copies of
directory information.  This single-provider/multiple-consumer
replication scheme is vital in high-volume environments where a single
slapd installation just doesn't provide the necessary availability or
reliability.  For extremely demanding environments where a single
point of failure is not acceptable, multi-provider replication is also
available. With multi-provider replication two or more nodes can
accept write operations allowing for redundancy at the provider level.

slapd includes support for LDAP Sync-based replication.

Proxy Cache: slapd can be configured as a caching LDAP proxy service.

Configuration: slapd is highly configurable through a single
configuration file which allows you to change just about everything
you'd ever want to change.  Configuration options have reasonable
defaults, making your job much easier. Configuration can also be
performed dynamically using LDAP itself, which greatly improves
manageability.

1.10. What is lloadd and what can it do?
----------------------------------------

lloadd(8) is a daemon that provides an LDAPv3 load balancer service.
It is responsible for distributing requests across a set of slapd
instances.

See the Load Balancing with lloadd chapter for information about how
to configure and run lloadd(8).

Alternatively, the load balancer can run as a module embedded inside
of slapd.  This is also described in the Load Balancing with lloadd
chapter.


2. A Quick-Start Guide
======================

The following is a quick start guide to OpenLDAP Software 2.6,
including the Standalone LDAP Daemon, slapd(8).

It is meant to walk you through the basic steps needed to install and
configure OpenLDAP Software.  It should be used in conjunction with
the other chapters of this document, manual pages, and other materials
provided with the distribution (e.g. the INSTALL document) or on the
OpenLDAP web site (http://www.OpenLDAP.org), in particular the
OpenLDAP Software FAQ (http://www.OpenLDAP.org/faq/?file=2).

If you intend to run OpenLDAP Software seriously, you should review
all of this document before attempting to install the software.

Note: This quick start guide does not use strong authentication nor
any integrity or confidential protection services.  These services are
described in other chapters of the OpenLDAP Administrator's Guide.



1.   Get the software

     You can obtain a copy of the software by following the
     instructions on the OpenLDAP Software download page
     (http://www.openldap.org/software/download/).  It is recommended
     that new users start with the latest release.



2.   Unpack the distribution

     Pick a directory for the source to live under, change directory
     to there, and unpack the distribution using the following
     commands:

          gunzip -c openldap-VERSION.tgz | tar xvfB -

     then relocate yourself into the distribution directory:

          cd openldap-VERSION

     You'll have to replace VERSION with the version name of the
     release.



3.   Review documentation

     You should now review the COPYRIGHT, LICENSE, README and INSTALL
     documents provided with the distribution. The COPYRIGHT and
     LICENSE provide information on acceptable use, copying, and
     limitation of warranty of OpenLDAP Software.



     You should also review other chapters of this document. In
     particular, the Building and Installing OpenLDAP Software chapter
     of this document provides detailed information on prerequisite
     software and installation procedures.



4.   Run configure

     You will need to run the provided configure script to configure
     the distribution for building on your system.  The configure
     script accepts many command line options that enable or disable
     optional software features.  Usually the defaults are okay, but
     you may want to change them.  To get a complete list of options
     that configure accepts, use the --help option:

          ./configure --help

     However, given that you are using this guide, we'll assume you
     are brave enough to just let configure determine what's best:

          ./configure

     Assuming configure doesn't dislike your system, you can proceed
     with building the software.  If configure did complain, well,
     you'll likely need to go to the Software FAQ Installation section
     (http://www.openldap.org/faq/?file=8) and/or actually read the
     Building and Installing OpenLDAP Software chapter of this
     document.



5.   Build the software.

     The next step is to build the software.  This step has two parts,
     first we construct dependencies and then we compile the software:

          make depend

          make

     Both makes should complete without error.



6.   Test the build.

     To ensure a correct build, you should run the test suite (it only
     takes a few minutes):

          make test

     Tests which apply to your configuration will run and they should
     pass.  Some tests, such as the replication test, may be skipped.



7.   Install the software.

     You are now ready to install the software; this usually requires
     super-user privileges:

          su root -c 'make install'

     Everything should now be installed under /usr/local (or whatever
     installation prefix was used by configure).



8.   Edit the configuration file.

     Use your favorite editor to edit the provided slapd.ldif example
     (usually installed as /usr/local/etc/openldap/slapd.ldif) to
     contain a MDB database definition of the form:

          dn: olcDatabase=mdb,cn=config

          objectClass: olcDatabaseConfig

          objectClass: olcMdbConfig

          olcDatabase: mdb

          OlcDbMaxSize: 1073741824

          olcSuffix: dc=<MY-DOMAIN>,dc=<COM>

          olcRootDN: cn=Manager,dc=<MY-DOMAIN>,dc=<COM>

          olcRootPW: secret

          olcDbDirectory: /usr/local/var/openldap-data

          olcDbIndex: objectClass eq

     Be sure to replace <MY-DOMAIN> and <COM> with the appropriate
     domain components of your domain name.  For example, for
     example.com, use:

          dn: olcDatabase=mdb,cn=config

          objectClass: olcDatabaseConfig

          objectClass: olcMdbConfig

          olcDatabase: mdb

          OlcDbMaxSize: 1073741824

          olcSuffix: dc=example,dc=com

          olcRootDN: cn=Manager,dc=example,dc=com

          olcRootPW: secret

          olcDbDirectory: /usr/local/var/openldap-data

          olcDbIndex: objectClass eq

     If your domain contains additional components, such as
     eng.uni.edu.eu, use:

          dn: olcDatabase=mdb,cn=config

          objectClass: olcDatabaseConfig

          objectClass: olcMdbConfig

          olcDatabase: mdb

          OlcDbMaxSize: 1073741824

          olcSuffix: dc=eng,dc=uni,dc=edu,dc=eu

          olcRootDN: cn=Manager,dc=eng,dc=uni,dc=edu,dc=eu

          olcRootPW: secret

          olcDbDirectory: /usr/local/var/openldap-data

          olcDbIndex: objectClass eq

     Details regarding configuring slapd(8) can be found in the
     slapd-config(5) manual page and the Configuring slapd chapter of
     this document.  Note that the specified olcDbDirectory must exist
     prior to starting slapd(8).



9.   Import the configuration database

     You are now ready to import your configuration database for use
     by slapd(8), by running the command:

           su root -c /usr/local/sbin/slapadd -n 0 -F
          /usr/local/etc/slapd.d -l /usr/local/etc/openldap/slapd.ldif



10.  Start SLAPD.

     You are now ready to start the Standalone LDAP Daemon, slapd(8),
     by running the command:

          su root -c /usr/local/libexec/slapd -F
          /usr/local/etc/slapd.d

     To check to see if the server is running and configured
     correctly, you can run a search against it with ldapsearch(1). 
     By default, ldapsearch is installed as /usr/local/bin/ldapsearch:

          ldapsearch -x -b '' -s base '(objectclass=*)' namingContexts

     Note the use of single quotes around command parameters to
     prevent special characters from being interpreted by the shell. 
     This should return:

          dn:

          namingContexts: dc=example,dc=com

     Details regarding running slapd(8) can be found in the slapd(8)
     manual page and the Running slapd chapter of this document.



11.  Add initial entries to your directory.

     You can use ldapadd(1) to add entries to your LDAP directory.
     ldapadd expects input in LDIF form.  We'll do it in two steps:

     1.   create an LDIF file

     2.   run ldapadd

     Use your favorite editor and create an LDIF file that contains:

          dn: dc=<MY-DOMAIN>,dc=<COM>

          objectclass: dcObject

          objectclass: organization

          o: <MY ORGANIZATION>

          dc: <MY-DOMAIN>



          dn: cn=Manager,dc=<MY-DOMAIN>,dc=<COM>

          objectclass: organizationalRole

          cn: Manager

     Be sure to replace <MY-DOMAIN> and <COM> with the appropriate
     domain components of your domain name.  <MY ORGANIZATION> should
     be replaced with the name of your organization. When you cut and
     paste, be sure to trim any leading and trailing whitespace from
     the example.

          dn: dc=example,dc=com

          objectclass: dcObject

          objectclass: organization

          o: Example Company

          dc: example



          dn: cn=Manager,dc=example,dc=com

          objectclass: organizationalRole

          cn: Manager

     Now, you may run ldapadd(1) to insert these entries into your
     directory.

          ldapadd -x -D "cn=Manager,dc=<MY-DOMAIN>,dc=<COM>" -W -f
          example.ldif

     Be sure to replace <MY-DOMAIN> and <COM> with the appropriate
     domain components of your domain name.  You will be prompted for
     the "secret" specified in slapd.conf. For example, for
     example.com, use:

          ldapadd -x -D "cn=Manager,dc=example,dc=com" -W -f
          example.ldif

     where example.ldif is the file you created above.



     Additional information regarding directory creation can be found
     in the Database Creation and Maintenance Tools chapter of this
     document.



12.  See if it works.

     Now we're ready to verify the added entries are in your
     directory. You can use any LDAP client to do this, but our
     example uses the ldapsearch(1) tool.  Remember to replace
     dc=example,dc=com with the correct values for your site:

          ldapsearch -x -b 'dc=example,dc=com' '(objectclass=*)'

     This command will search for and retrieve every entry in the
     database.

You are now ready to add more entries using ldapadd(1) or another LDAP
client, experiment with various configuration options, backend
arrangements, etc..

Note that by default, the slapd(8) database grants read access to
everybody excepting the super-user (as specified by the rootdn
configuration directive).  It is highly recommended that you establish
controls to restrict access to authorized users. Access controls are
discussed in the Access Control chapter. You are also encouraged to
read the Security Considerations, Using SASL and Using TLS sections.

The following chapters provide more detailed information on making,
installing, and running slapd(8).


3. The Big Picture - Configuration Choices
==========================================

This section gives a brief overview of various LDAP directory
configurations, and how your Standalone LDAP Daemon slapd(8) fits in
with the rest of the world.

3.1. Local Directory Service
----------------------------

In this configuration, you run a slapd(8) instance which provides
directory service for your local domain only. It does not interact
with other directory servers in any way. This configuration is shown
in Figure 3.1.

** Unable to import figure config_local.png **

Figure 3.1: Local service configuration.

Use this configuration if you are just starting out (it's the one the
quick-start guide makes for you) or if you want to provide a local
service and are not interested in connecting to the rest of the world.
It's easy to upgrade to another configuration later if you want.

3.2. Local Directory Service with Referrals
-------------------------------------------

In this configuration, you run a slapd(8) instance which provides
directory service for your local domain and configure it to return
referrals to other servers capable of handling requests.  You may run
this service (or services) yourself or use one provided to you. This
configuration is shown in Figure 3.2.

** Unable to import figure config_ref.png **

Figure 3.2: Local service with referrals

Use this configuration if you want to provide local service and
participate in the Global Directory,  or you want to delegate
responsibility for subordinate entries to another server.

3.3. Replicated Directory Service
---------------------------------

slapd(8) includes support for LDAP Sync-based replication, called
syncrepl, which may be used to maintain shadow copies of directory
information on multiple directory servers.   In its most basic
configuration, the provider is a syncrepl provider and one or more
consumer (or shadow) are syncrepl consumers.  An example
provider-consumer configuration is shown in figure 3.3. Multi-Provider
configurations are also supported.

** Unable to import figure config_repl.png **

Figure 3.3: Replicated Directory Services

This configuration can be used in conjunction with either of the first
two configurations in situations where a single slapd(8) instance does
not provide the required reliability or availability.

3.4. Distributed Local Directory Service
----------------------------------------

In this configuration, the local service is partitioned into smaller
services, each of which may be replicated, and glued together with
superior and subordinate referrals.


4. Building and Installing OpenLDAP Software
============================================

This chapter details how to build and install the OpenLDAP Software
package including slapd(8), the Standalone LDAP Daemon.  Building and
installing OpenLDAP Software requires several steps: installing
prerequisite software, configuring OpenLDAP Software itself, making,
and finally installing.  The following sections describe this process
in detail.

4.1. Obtaining and Extracting the Software
------------------------------------------

You can obtain OpenLDAP Software from the project's download page at
http://www.openldap.org/software/download/ or directly from the
project's FTP service at ftp://ftp.openldap.org/pub/OpenLDAP/.

The project makes available two series of packages for general use. 
The project makes releases as new features and bug fixes come
available.  Though the project takes steps to improve stability of
these releases, it is common for problems to arise only after release.
 The stable release is the latest release which has demonstrated
stability through general use.

Users of OpenLDAP Software can choose, depending on their desire for
the latest features versus demonstrated stability, the most
appropriate series to install.

After downloading OpenLDAP Software, you need to extract the
distribution from the compressed archive file and change your working
directory to the top directory of the distribution:

     gunzip -c openldap-VERSION.tgz | tar xf -

     cd openldap-VERSION

You'll have to replace VERSION with the version name of the release.

You should now review the COPYRIGHT, LICENSE, README and INSTALL
documents provided with the distribution.  The COPYRIGHT and LICENSE
provide information on acceptable use, copying, and limitation of
warranty of OpenLDAP Software. The README and INSTALL documents
provide detailed information on prerequisite software and installation
procedures.

4.2. Prerequisite software
--------------------------

OpenLDAP Software relies upon a number of software packages
distributed by third parties.  Depending on the features you intend to
use, you may have to download and install a number of additional
software packages.  This section details commonly needed third party
software packages you might have to install.  However, for an
up-to-date prerequisite information, the README document should be
consulted.  Note that some of these third party packages may depend on
additional software packages.  Install each package per the
installation instructions provided with it.

4.2.1. Transport Layer Security
-------------------------------

OpenLDAP clients and servers require installation of OpenSSL or GnuTLS
TLS libraries to provide Transport Layer Security services.  Though
some operating systems may provide these libraries as part of the base
system or as an optional software component, OpenSSL and GnuTLS often
require separate installation.

OpenSSL is available from http://www.openssl.org/. GnuTLS is available
from http://www.gnu.org/software/gnutls/.

OpenLDAP Software will not be fully LDAPv3 compliant unless OpenLDAP's
configure detects a usable TLS library.

4.2.2. Simple Authentication and Security Layer
-----------------------------------------------

OpenLDAP clients and servers require installation of Cyrus SASL
libraries to provide Simple Authentication and Security Layer
services.  Though some operating systems may provide this library as
part of the base system or as an optional software component, Cyrus
SASL often requires separate installation.

Cyrus SASL is available from
http://asg.web.cmu.edu/sasl/sasl-library.html. Cyrus SASL will make
use of OpenSSL and Kerberos/GSSAPI libraries if preinstalled.

OpenLDAP Software will not be fully LDAPv3 compliant unless OpenLDAP's
configure detects a usable Cyrus SASL installation.

4.2.3. Kerberos Authentication Service
--------------------------------------

OpenLDAP clients and servers support Kerberos authentication services.
 In particular, OpenLDAP supports the Kerberos V GSS-API SASL
authentication mechanism known as the GSSAPI mechanism.  This feature
requires, in addition to Cyrus SASL libraries, either Heimdal or MIT
Kerberos V libraries.

Heimdal Kerberos is available from
https://github.com/heimdal/heimdal/. MIT Kerberos is available from
http://web.mit.edu/kerberos/www/.

Use of strong authentication services, such as those provided by
Kerberos, is highly recommended.

4.2.4. Database Software
------------------------

OpenLDAP's slapd(8) MDB primary database backend uses the LMDB
software included with the OpenLDAP source.  There is no need to
download any additional software to have MDB support.

4.2.5. Threads
--------------

OpenLDAP is designed to take advantage of threads.  OpenLDAP supports
POSIX pthreads, NT threads and a number of other varieties.  configure
will complain if it cannot find a suitable thread subsystem.   If this
occurs, please consult the Software|Installation|Platform Hints
section of the OpenLDAP FAQ http://www.openldap.org/faq/.

4.2.6. TCP Wrappers
-------------------

slapd(8) supports TCP Wrappers (IP level access control filters) if
preinstalled.  Use of TCP Wrappers or other IP-level access filters
(such as those provided by an IP-level firewall) is recommended for
servers containing non-public information.

4.3. Running configure
----------------------

Now you should probably run the configure script with the --help
option. This will give you a list of options that you can change when
building OpenLDAP.  Many of the features of OpenLDAP can be enabled or
disabled using this method.

        ./configure --help

The configure script also looks for certain variables on the command
line and in the environment.  These include:

Table 4.1: Variables

Variable                           Description
.................................. .................................. 
CC                                 Specify alternative C Compiler
CFLAGS                             Specify additional compiler flags
CPPFLAGS                           Specify C Preprocessor flags
LDFLAGS                            Specify linker flags
LIBS                               Specify additional libraries

Now run the configure script with any desired configuration options or
variables.

        ./configure [options] [variable=value ...]

As an example, let's assume that we want to install OpenLDAP with MDB
backend and TCP Wrappers support.  By default, MDB is enabled and TCP
Wrappers is not.  So, we just need to specify --enable-wrappers to
include TCP Wrappers support:

        ./configure --enable-wrappers

However, this will fail to locate dependent software not installed in
system directories.  For example, if TCP Wrappers headers and
libraries are installed in /usr/local/include and /usr/local/lib
respectively, the configure script should typically be called as
follows:

        ./configure --enable-wrappers \
                CPPFLAGS="-I/usr/local/include" \
                LDFLAGS="-L/usr/local/lib -Wl,-rpath,/usr/local/lib"

The configure script will normally auto-detect appropriate settings. 
If you have problems at this stage, consult any platform specific
hints and check your configure options, if any.

4.4. Building the Software
--------------------------

Once you have run the configure script the last line of output should
be:

        Please "make depend" to build dependencies

If the last line of output does not match, configure has failed, and
you will need to review its output to determine what went wrong. You
should not proceed until configure completes successfully.

To build dependencies, run:

        make depend

Now build the software, this step will actually compile OpenLDAP.

        make

You should examine the output of this command carefully to make sure
everything is built correctly.  Note that this command builds the LDAP
libraries and associated clients as well as slapd(8).

4.5. Testing the Software
-------------------------

Once the software has been properly configured and successfully made,
you should run the test suite to verify the build.

        make test

Tests which apply to your configuration will run and they should pass.
Some tests, such as the replication test, may be skipped if not
supported by your configuration.

4.6. Installing the Software
----------------------------

Once you have successfully tested the software, you are ready to
install it.  You will need to have write permission to the
installation directories you specified when you ran configure.  By
default OpenLDAP Software is installed in /usr/local.  If you changed
this setting with the --prefix configure option, it will be installed
in the location you provided.

Typically, the installation requires super-user privileges. From the
top level OpenLDAP source directory, type:

        su root -c 'make install'

and enter the appropriate password when requested.

You should examine the output of this command carefully to make sure
everything is installed correctly. You will find the configuration
files for slapd(8) in /usr/local/etc/openldap by default.  See the
chapter Configuring slapd for additional information.


5. Configuring slapd
====================

Once the software has been built and installed, you are ready to
configure slapd(8) for use at your site.

OpenLDAP 2.3 and later have transitioned to using a dynamic runtime
configuration engine, slapd-config(5).  slapd-config(5)

o    is fully LDAP-enabled

o    is managed using the standard LDAP operations

o    stores its configuration data in an LDIF database, generally in
     the /usr/local/etc/openldap/slapd.d directory.

o    allows all of slapd's configuration options to be changed on the
     fly, generally without requiring a server restart for the changes
     to take effect.

This chapter describes the general format of the slapd-config(5)
configuration system, followed by a detailed description of commonly
used settings.

The older style slapd.conf(5) file is still supported, but its use is
deprecated and support for it will be withdrawn in a future OpenLDAP
release.  Configuring slapd(8) via slapd.conf(5) is described in the
next chapter.

Refer to slapd(8) for information on how to have slapd automatically
convert from slapd.conf(5) to slapd-config(5).

Note: Although the slapd-config(5) system stores its configuration as
(text-based) LDIF files, you should never edit any of the LDIF files
directly.  Configuration changes should be performed via LDAP
operations, e.g. ldapadd(1), ldapdelete(1), or ldapmodify(1). For
offline modifications (when the server is not running), use slapadd(8)
and slapmodify(8).

Note: You will need to continue to use the older slapd.conf(5)
configuration system if your OpenLDAP installation requires the use of
one or more backends or overlays that have not been updated to use the
slapd-config(5) system.  As of OpenLDAP 2.4.33, all of the official
backends have been updated.  There may be additional contributed or
experimental overlays that also have not been updated.

5.1. Configuration Layout
-------------------------

The slapd configuration is stored as a special LDAP directory with a
predefined schema and DIT. There are specific objectClasses used to
carry global configuration options, schema definitions, backend and
database definitions, and assorted other items. A sample config tree
is shown in Figure 5.1.

** Unable to import figure config_dit.png **

Figure 5.1: Sample configuration tree.

Other objects may be part of the configuration but were omitted from
the illustration for clarity.

The slapd-config configuration tree has a very specific structure. The
root of the tree is named cn=config and contains global configuration
settings. Additional settings are contained in separate child entries:

o    Dynamically loaded modules

          These may only be used if the --enable-modules option was
          used to configure the software.

o    Schema definitions

          The cn=schema,cn=config entry contains the system schema
          (all the schema that is hard-coded in slapd).

          Child entries of cn=schema,cn=config contain user schema as
          loaded from config files or added at runtime.

o    Backend-specific configuration

o    Database-specific configuration

          Overlays are defined in children of the Database entry.

          Databases and Overlays may also have other miscellaneous
          children.

The usual rules for LDIF files apply to the configuration information:
Comment lines beginning with a '#' character are ignored.  If a line
begins with a single space, it is considered a continuation of the
previous line (even if the previous line is a comment) and the single
leading space is removed. Entries are separated by blank lines.

The general layout of the config LDIF is as follows:

        # global configuration settings
        dn: cn=config
        objectClass: olcGlobal
        cn: config
        <global config settings>

        # schema definitions
        dn: cn=schema,cn=config
        objectClass: olcSchemaConfig
        cn: schema
        <system schema>

        dn: cn={X}core,cn=schema,cn=config
        objectClass: olcSchemaConfig
        cn: {X}core
        <core schema>

        # additional user-specified schema
        ...

        # backend definitions
        dn: olcBackend=<typeA>,cn=config
        objectClass: olcBackendConfig
        olcBackend: <typeA>
        <backend-specific settings>

        # database definitions
        dn: olcDatabase={X}<typeA>,cn=config
        objectClass: olcDatabaseConfig
        olcDatabase: {X}<typeA>
        <database-specific settings>

        # subsequent definitions and settings
        ...

Some of the entries listed above have a numeric index "{X}" in their
names. While most configuration settings have an inherent ordering
dependency (i.e., one setting must take effect before a subsequent one
may be set), LDAP databases are inherently unordered. The numeric
index is used to enforce a consistent ordering in the configuration
database, so that all ordering dependencies are preserved. In most
cases the index does not have to be provided; it will be automatically
generated based on the order in which entries are created.

Configuration directives are specified as values of individual
attributes. Most of the attributes and objectClasses used in the slapd
configuration have a prefix of "olc" (OpenLDAP Configuration) in their
names. Generally there is a one-to-one correspondence between the
attributes and the old-style slapd.conf configuration keywords, using
the keyword as the attribute name, with the "olc" prefix attached.

A configuration directive may take arguments.  If so, the arguments
are separated by whitespace.  If an argument contains whitespace, the
argument should be enclosed in double quotes "like this". In the
descriptions that follow, arguments that should be replaced by actual
text are shown in brackets <>.

The distribution contains an example configuration file that will be
installed in the /usr/local/etc/openldap directory. A number of files
containing schema definitions (attribute types and object classes) are
also provided in the /usr/local/etc/openldap/schema directory.

5.2. Configuration Directives
-----------------------------

This section details commonly used configuration directives.  For a
complete list, see the slapd-config(5) manual page.  This section will
treat the configuration directives in a top-down order, starting with
the global directives in the cn=config entry. Each directive will be
described along with its default value (if any) and an example of its
use.

5.2.1. cn=config
----------------

Directives contained in this entry generally apply to the server as a
whole. Most of them are system or connection oriented, not database
related. This entry must have the olcGlobal objectClass.

5.2.1.1. olcIdleTimeout: <integer>
----------------------------------

Specify the number of seconds to wait before forcibly closing an idle
client connection.  A value of 0, the default, disables this feature.

5.2.1.2. olcLogLevel: <level>
-----------------------------

This directive specifies the level at which log statements and
operation statistics should be sent to syslog (currently logged to the
syslogd(8) LOG_LOCAL4 facility). You must have configured OpenLDAP
--enable-debug (the default) for this to work, except for the two
statistics levels, which are always enabled. Log levels may be
specified as integers or by keyword. Multiple log levels may be used
and the levels are additive. The possible values for <level> are:

Table 5.1: Logging Levels

                 Level Keyword                 Description
...................... ....................... ...................... 
                    -1 any                     enable all debugging
                     0                         no debugging
                     1 (0x1 trace)             trace function calls
                     2 (0x2 packets)           debug packet handling
                     4 (0x4 args)              heavy trace debugging
                     8 (0x8 conns)             connection management
                    16 (0x10 BER)              print out packets sent
                                               and received
                    32 (0x20 filter)           search filter
                                               processing
                    64 (0x40 config)           configuration
                                               processing
                   128 (0x80 ACL)              access control list
                                               processing
                   256 (0x100 stats)           stats log
                                               connections/operations/results
                   512 (0x200 stats2)          stats log entries sent
                  1024 (0x400 shell)           print communication
                                               with shell backends
                  2048 (0x800 parse)           print entry parsing
                                               debugging
                 16384 (0x4000 sync)           syncrepl consumer
                                               processing
                 32768 (0x8000 none)           only messages that get
                                               logged regardless of
                                               configured log level

The desired log level can be input as a single integer that combines
the (ORed) desired levels, both in decimal or in hexadecimal notation,
as a list of integers (that are ORed internally), or as a list of the
names that are shown between brackets, such that

                olcLogLevel 129
                olcLogLevel 0x81
                olcLogLevel 128 1
                olcLogLevel 0x80 0x1
                olcLogLevel acl trace

are equivalent.

Examples:

 olcLogLevel -1

This will enable all log levels.

 olcLogLevel conns filter

Just log the connection and search filter processing.

 olcLogLevel none

Log those messages that are logged regardless of the configured
loglevel. This differs from setting the log level to 0, when no
logging occurs. At least the None level is required to have high
priority messages logged.

Default:

 olcLogLevel stats

Basic stats logging is configured by default.

5.2.1.3. olcReferral <URI>
--------------------------

This directive specifies the referral to pass back when slapd cannot
find a local database to handle a request.

Example:

        olcReferral: ldap://root.openldap.org

This will refer non-local queries to the global root LDAP server at
the OpenLDAP Project. Smart LDAP clients can re-ask their query at
that server, but note that most of these clients are only going to
know how to handle simple LDAP URLs that contain a host part and
optionally a distinguished name part.

5.2.1.4. Sample Entry
---------------------

dn: cn=config
objectClass: olcGlobal
cn: config
olcIdleTimeout: 30
olcLogLevel: Stats
olcReferral: ldap://root.openldap.org

5.2.2. cn=module
----------------

If support for dynamically loaded modules was enabled when configuring
slapd, cn=module entries may be used to specify sets of modules to
load. Module entries must have the olcModuleList objectClass.

5.2.2.1. olcModuleLoad: <filename>
----------------------------------

Specify the name of a dynamically loadable module to load. The
filename may be an absolute path name or a simple filename.
Non-absolute names are searched for in the directories specified by
the olcModulePath directive.

5.2.2.2. olcModulePath: <pathspec>
----------------------------------

Specify a list of directories to search for loadable modules.
Typically the path is colon-separated but this depends on the
operating system.

5.2.2.3. Sample Entries
-----------------------

dn: cn=module{0},cn=config
objectClass: olcModuleList
cn: module{0}
olcModuleLoad: /usr/local/lib/smbk5pwd.la

dn: cn=module{1},cn=config
objectClass: olcModuleList
cn: module{1}
olcModulePath: /usr/local/lib:/usr/local/lib/slapd
olcModuleLoad: accesslog.la
olcModuleLoad: pcache.la

5.2.3. cn=schema
----------------

The cn=schema entry holds all of the schema definitions that are
hard-coded in slapd. As such, the values in this entry are generated
by slapd so no schema values need to be provided in the config file.
The entry must still be defined though, to serve as a base for the
user-defined schema to add in underneath. Schema entries must have the
olcSchemaConfig objectClass.

5.2.3.1. olcAttributeTypes: <RFC4512 Attribute Type Description>
----------------------------------------------------------------

This directive defines an attribute type. Please see the Schema
Specification chapter for information regarding how to use this
directive.

5.2.3.2. olcObjectClasses: <RFC4512 Object Class Description>
-------------------------------------------------------------

This directive defines an object class. Please see the Schema
Specification chapter for information regarding how to use this
directive.

5.2.3.3. Sample Entries
-----------------------

dn: cn=schema,cn=config
objectClass: olcSchemaConfig
cn: schema

dn: cn=test,cn=schema,cn=config
objectClass: olcSchemaConfig
cn: test
olcAttributeTypes: ( 1.1.1
  NAME 'testAttr'
  EQUALITY integerMatch
  SYNTAX 1.3.6.1.4.1.1466.115.121.1.27 )
olcAttributeTypes: ( 1.1.2 NAME 'testTwo' EQUALITY caseIgnoreMatch
  SUBSTR caseIgnoreSubstringsMatch SYNTAX 1.3.6.1.4.1.1466.115.121.1.44 )
olcObjectClasses: ( 1.1.3 NAME 'testObject'
  MAY ( testAttr $ testTwo ) AUXILIARY )

5.2.4. Backend-specific Directives
----------------------------------

Backend directives apply to all database instances of the same type
and, depending on the directive, may be overridden by database
directives. Backend entries must have the olcBackendConfig
objectClass.

5.2.4.1. olcBackend: <type>
---------------------------

This directive names a backend-specific configuration entry. <type>
should be one of the supported backend types listed in Table 5.2.

Table 5.2: Database Backends

Types                              Description
.................................. .................................. 
asyncmet                           a Asynchronous Metadirectory
                                   backend
config                             Slapd configuration backend
dnssrv                             DNS SRV backend
ldap                               Lightweight Directory Access
                                   Protocol (Proxy) backend
ldif                               Lightweight Data Interchange
                                   Format backend
mdb                                Memory-Mapped DB backend
meta                               Metadirectory backend
monitor                            Monitor backend
null                               Null backend
passwd                             Provides read-only access to
                                   passwd(5)
perl                               Perl Programmable backend
relay                              Relay backend
sock                               Socket backend
sql                                SQL Programmable backend
wt                                 WiredTiger backend

Example:

        olcBackend: mdb

This marks the beginning of a new MDB backend definition. At present,
only back-mdb implements any options of this type, so this setting is
not needed for any other backends.

5.2.4.2. Sample Entry
---------------------

 dn: olcBackend=mdb,cn=config
 objectClass: olcBackendConfig
 olcBackend: mdb
 olcBkMdbIdlExp: 16

5.2.5. Database-specific Directives
-----------------------------------

Directives in this section are supported by every type of database.
Database entries must have the olcDatabaseConfig objectClass.

5.2.5.1. olcDatabase: [{<index>}]<type>
---------------------------------------

This directive names a specific database instance. The numeric
{<index>} may be provided to distinguish multiple databases of the
same type. Usually the index can be omitted, and slapd will generate
it automatically. <type> should be one of the supported backend types
listed in Table 5.2 or the frontend type.

The frontend is a special database that is used to hold database-level
options that should be applied to all the other databases. Subsequent
database definitions may also override some frontend settings.

The config database is also special; both the config and the frontend
databases are always created implicitly even if they are not
explicitly configured, and they are created before any other
databases.

Example:

        olcDatabase: mdb

This marks the beginning of a new MDB database instance.

5.2.5.2. olcAccess: to <what> [ by <who> [<accesslevel>] [<control>] ]+
-----------------------------------------------------------------------

This directive grants access (specified by <accesslevel>) to a set of
entries and/or attributes (specified by <what>) by one or more
requestors (specified by <who>). See the Access Control section of
this guide for basic usage.

Note: If no olcAccess directives are specified, the default access
control policy, to * by * read, allows all users (both authenticated
and anonymous) read access.

Note: Access controls defined in the frontend are appended to all
other databases' controls.

5.2.5.3. olcReadonly { TRUE | FALSE }
-------------------------------------

This directive puts the database into "read-only" mode. Any attempts
to modify the database will return an "unwilling to perform" error. 
If set on a consumer, modifications sent by syncrepl will still occur.

Default:

        olcReadonly: FALSE

5.2.5.4. olcRootDN: <DN>
------------------------

This directive specifies the DN that is not subject to access control
or administrative limit restrictions for operations on this database. 
The DN need not refer to an entry in this database or even in the
directory. The DN may refer to a SASL identity.

Entry-based Example:

        olcRootDN: cn=Manager,dc=example,dc=com

SASL-based Example:

        olcRootDN: uid=root,cn=example.com,cn=digest-md5,cn=auth

See the SASL Authentication section for information on SASL
authentication identities.

5.2.5.5. olcRootPW: <password>
------------------------------

This directive can be used to specify a password for the DN for the
rootdn (when the rootdn is set to a DN within the database).

Example:

        olcRootPW: secret

It is also permissible to provide a hash of the password in RFC2307
form.  slappasswd(8) may be used to generate the password hash.

Example:

        olcRootPW: {SSHA}ZKKuqbEKJfKSXhUbHG3fG8MDn9j1v4QN

The hash was generated using the command slappasswd -s secret.

5.2.5.6. olcSizeLimit: <integer>
--------------------------------

This directive specifies the maximum number of entries to return from
a search operation.

Default:

        olcSizeLimit: 500

See the Limits section of this guide and slapd-config(5) for more
details.

5.2.5.7. olcSuffix: <dn suffix>
-------------------------------

This directive specifies the DN suffix of queries that will be passed
to this backend database. Multiple suffix lines can be given, and
usually at least one is required for each database definition. (Some
backend types, such as frontend and monitor use a hard-coded suffix
which may not be overridden in the configuration.)

Example:

        olcSuffix: dc=example,dc=com

Queries with a DN ending in "dc=example,dc=com" will be passed to this
backend.

Note: When the backend to pass a query to is selected, slapd looks at
the suffix value(s) in each database definition in the order in which
they were configured. Thus, if one database suffix is a prefix of
another, it must appear after it in the configuration.

5.2.5.8. olcSyncrepl
--------------------

        olcSyncrepl: rid=<replica ID>
                provider=ldap[s]://<hostname>[:port]
                [type=refreshOnly|refreshAndPersist]
                [interval=dd:hh:mm:ss]
                [retry=[<retry interval> <# of retries>]+]
                searchbase=<base DN>
                [filter=<filter str>]
                [scope=sub|one|base]
                [attrs=<attr list>]
                [exattrs=<attr list>]
                [attrsonly]
                [sizelimit=<limit>]
                [timelimit=<limit>]
                [schemachecking=on|off]
                [bindmethod=simple|sasl]
                [binddn=<DN>]
                [saslmech=<mech>]
                [authcid=<identity>]
                [authzid=<identity>]
                [credentials=<passwd>]
                [realm=<realm>]
                [secprops=<properties>]
                [starttls=yes|critical]
                [tls_cert=<file>]
                [tls_key=<file>]
                [tls_cacert=<file>]
                [tls_cacertdir=<path>]
                [tls_reqcert=never|allow|try|demand]
                [tls_cipher_suite=<ciphers>]
                [tls_crlcheck=none|peer|all]
                [logbase=<base DN>]
                [logfilter=<filter str>]
                [syncdata=default|accesslog|changelog]

This directive specifies the current database as a consumer of the
provider content by establishing the current slapd(8) as a replication
consumer site running a syncrepl replication engine. The provider
database is located at the provider site specified by the provider
parameter. The consumer database is kept up-to-date with the provider
content using the LDAP Content Synchronization protocol. See RFC4533
for more information on the protocol.

The rid parameter is used for identification of the current syncrepl
directive within the replication consumer server, where <replica ID>
uniquely identifies the syncrepl specification described by the
current syncrepl directive. <replica ID> is non-negative and is no
more than three decimal digits in length.

The provider parameter specifies the replication provider site
containing the provider content as an LDAP URI. The provider parameter
specifies a scheme, a host and optionally a port where the provider
slapd instance can be found. Either a domain name or IP address may be
used for <hostname>. Examples are ldap://provider.example.com:389 or
ldaps://192.168.1.1:636. If <port> is not given, the standard LDAP
port number (389 or 636) is used. Note that the syncrepl uses a
consumer-initiated protocol, and hence its specification is located on
the consumer.

The content of the syncrepl consumer is defined using a search
specification as its result set. The consumer slapd will send search
requests to the provider slapd according to the search specification.
The search specification includes searchbase, scope, filter, attrs,
exattrs, attrsonly, sizelimit, and timelimit parameters as in the
normal search specification. The searchbase parameter has no default
value and must always be specified. The scope defaults to sub, the
filter defaults to (objectclass=*), attrs defaults to "*,+" to
replicate all user and operational attributes, and attrsonly is unset
by default. Both sizelimit and timelimit default to "unlimited", and
only positive integers or "unlimited" may be specified. The exattrs
option may also be used to specify attributes that should be omitted
from incoming entries.

The LDAP Content Synchronization protocol has two operation types:
refreshOnly and refreshAndPersist. The operation type is specified by
the type parameter. In the refreshOnly operation, the next
synchronization search operation is periodically rescheduled at an
interval time after each synchronization operation finishes. The
interval is specified by the interval parameter. It is set to one day
by default. In the refreshAndPersist operation, a synchronization
search remains persistent in the provider slapd instance. Further
updates to the provider will generate searchResultEntry to the
consumer slapd as the search responses to the persistent
synchronization search.

If an error occurs during replication, the consumer will attempt to
reconnect according to the retry parameter which is a list of the
<retry interval> and <# of retries> pairs. For example, retry="60 10
300 3" lets the consumer retry every 60 seconds for the first 10 times
and then retry every 300 seconds for the next three times before stop
retrying. + in <#  of retries> means indefinite number of retries
until success.

The schema checking can be enforced at the LDAP Sync consumer site by
turning on the schemachecking parameter. If it is turned on, every
replicated entry will be checked for its schema as the entry is stored
on the consumer. Every entry in the consumer should contain those
attributes required by the schema definition. If it is turned off,
entries will be stored without checking schema conformance. The
default is off.

The binddn parameter gives the DN to bind as for the syncrepl searches
to the provider slapd. It should be a DN which has read access to the
replication content in the provider database.

The bindmethod is simple or sasl, depending on whether simple
password-based authentication or SASL authentication is to be used
when connecting to the provider slapd instance.

Simple authentication should not be used unless adequate data
integrity and confidentiality protections are in place (e.g. TLS or
IPsec). Simple authentication requires specification of binddn and
credentials parameters.

SASL authentication is generally recommended.  SASL authentication
requires specification of a mechanism using the saslmech parameter.
Depending on the mechanism, an authentication identity and/or
credentials can be specified using authcid and credentials,
respectively.  The authzid parameter may be used to specify an
authorization identity.

The realm parameter specifies a realm which a certain mechanisms
authenticate the identity within. The secprops parameter specifies
Cyrus SASL security properties.

The starttls parameter specifies use of the StartTLS extended
operation to establish a TLS session before authenticating to the
provider. If the critical argument is supplied, the session will be
aborted if the StartTLS request fails.  Otherwise the syncrepl session
continues without TLS.  The tls_reqcert setting defaults to "demand"
and the other TLS settings default to the same as the main slapd TLS
settings.

Rather than replicating whole entries, the consumer can query logs of
data modifications.  This mode of operation is referred to as delta
syncrepl.  In addition to the above parameters, the logbase and
logfilter parameters must be set appropriately for the log that will
be used. The syncdata parameter must be set to either "accesslog" if
the log conforms to the slapo-accesslog(5) log format, or "changelog"
if the log conforms to the obsolete changelog format. If the syncdata
parameter is omitted or set to "default" then the log parameters are
ignored.

The syncrepl replication mechanism is supported by the mdb backend.

See the LDAP Sync Replication chapter of this guide for more
information on how to use this directive.

5.2.5.9. olcTimeLimit: <integer>
--------------------------------

This directive specifies the maximum number of seconds (in real time)
slapd will spend answering a search request. If a request is not
finished in this time, a result indicating an exceeded timelimit will
be returned.

Default:

        olcTimeLimit: 3600

See the Limits section of this guide and slapd-config(5) for more
details.

5.2.5.10. olcUpdateref: <URL>
-----------------------------

This directive is only applicable in a replica (or shadow) slapd(8)
instance. It specifies the URL to return to clients which submit
update requests upon the replica. If specified multiple times, each
URL is provided.

Example:

        olcUpdateref:   ldap://provider.example.net

5.2.5.11. Sample Entries
------------------------

dn: olcDatabase=frontend,cn=config
objectClass: olcDatabaseConfig
objectClass: olcFrontendConfig
olcDatabase: frontend
olcReadOnly: FALSE

dn: olcDatabase=config,cn=config
objectClass: olcDatabaseConfig
olcDatabase: config
olcRootDN: cn=Manager,dc=example,dc=com

5.2.6. MDB Backend Directives
-----------------------------

Directives in this category only apply to the MDB database backend.
They will apply to all "database mdb" instances in the configuration.
For a complete reference of MDB backend configuration directives, see
slapd-mdb(5).

5.2.6.1. olcBkMdbIdlExp <exponent>
----------------------------------

Specify a power of 2 for the maximum size of an index slot. The
default is 16, yielding a maximum slot size of 2^16 or 65536. The
specified value must be in the range of 16-30.

This setting helps with the case where certain search filters are slow
to return results due to an index slot having collapsed to a range
value.  This occurs when the number of candidate entries that match
the filter for the index slot exceed the configured slot size.

If this setting is decreased on a server with existing MDB databases,
each db will immediately need its indices to be rebuilt while slapd is
offline with the "slapindex -q -t" command.

If this setting is increased on a server with existing MDB databases,
each db will need its indices rebuilt to take advantage of the change
for indices that have already been converted to ranges.

5.2.7. MDB Database Directives
------------------------------

Directives in this category apply to the MDB database backend. They
are used in an olcDatabase entry in addition to the generic database
directives defined above.  For a complete reference of MDB
configuration directives, see slapd-mdb(5). In addition to the
olcDatabaseConfig objectClass, MDB database entries must have the
olcMdbConfig objectClass.

5.2.7.1. olcDbDirectory: <directory>
------------------------------------

This directive specifies the directory where the MDB files containing
the database and associated indices live.

Default:

        olcDbDirectory: /usr/local/var/openldap-data

5.2.7.2. olcDbCheckpoint: <kbyte> <min>
---------------------------------------

This directive specifies the frequency for flushing the database disk
buffers. This directive is only needed if the olcDbNoSync option is
TRUE. The checkpoint will occur if either <kbyte> data has been
written or <min> minutes have passed since the last checkpoint. Both
arguments default to zero, in which case they are ignored. When the
<min> argument is non-zero, an internal task will run every <min>
minutes to perform the checkpoint. Note: currently the _kbyte_ setting
is unimplemented.

Example:

        olcDbCheckpoint: 1024 10

5.2.7.3. olcDbEnvFlags: {nosync,nometasync,writemap,mapasync,nordahead}
-----------------------------------------------------------------------

This option specifies flags for finer-grained control of  the  LMDB 
library's operation.

o    nosync: This is exactly the same as the dbnosync directive.

o    nometasync: Flush the data on a commit, but skip the sync of the
     meta page. This mode is slightly faster than doing a full sync,
     but can potentially lose the last committed transaction if the
     operating system crashes. If both nometasync and nosync are set,
     the nosync flag takes precedence.

o    writemap: Use a writable memory map instead of just read-only.
     This speeds up write operations but makes the database vulnerable
     to corruption in case any bugs in slapd cause stray writes into
     the mmap region.

o    mapasync: When using a writable memory map and performing flushes
     on each commit, use an asynchronous flush instead of a
     synchronous flush (the default). This option has no effect if
     writemap has not been set. It also has no effect if nosync is
     set.

o    nordahead: Turn off file readahead. Usually the OS performs
     readahead on every read request. This usually boosts read
     performance but can be harmful to random access read performance
     if the system's memory is full and the DB is larger than RAM.
     This option is not implemented on Windows.

5.2.7.4. olcDbIndex: {<attrlist> | default} [pres,eq,approx,sub,none]
---------------------------------------------------------------------

This directive specifies the indices to maintain for the given
attribute. If only an <attrlist> is given, the default indices are
maintained. The index keywords correspond to the common types of
matches that may be used in an LDAP search filter.

Example:

        olcDbIndex: default pres,eq
        olcDbIndex: uid
        olcDbIndex: cn,sn pres,eq,sub
        olcDbIndex: objectClass eq

The first line sets the default set of indices to maintain to present
and equality.  The second line causes the default (pres,eq) set of
indices to be maintained for the uid attribute type. The third line
causes present, equality, and substring indices to be maintained for
cn and sn attribute types.  The fourth line causes an equality index
for the objectClass attribute type.

There is no index keyword for inequality matches. Generally these
matches do not use an index. However, some attributes do support
indexing for inequality matches, based on the equality index.

A substring index can be more explicitly specified as subinitial,
subany, or subfinal, corresponding to the three possible components of
a substring match filter. A subinitial index only indexes substrings
that appear at the beginning of an attribute value. A subfinal index
only indexes substrings that appear at the end of an attribute value,
while subany indexes substrings that occur anywhere in a value.

Note that by default, setting an index for an attribute also affects
every subtype of that attribute. E.g., setting an equality index on
the name attribute causes cn, sn, and every other attribute that
inherits from name to be indexed.

By default, no indices are maintained.  It is generally advised that
minimally an equality index upon objectClass be maintained.

        olcDbIndex: objectClass eq

Additional indices should be configured corresponding to the most
common searches that are used on the database. Presence indexing
should not be configured for an attribute unless the attribute occurs
very rarely in the database, and presence searches on the attribute
occur very frequently during normal use of the directory. Most
applications don't use presence searches, so usually presence indexing
is not very useful.

If this setting is changed while slapd is running, an internal task
will be run to generate the changed index data. All server operations
can continue as normal while the indexer does its work.  If slapd is
stopped before the index task completes, indexing will have to be
manually completed using the slapindex tool.

5.2.7.5. olcDbMaxEntrySize: <bytes>
-----------------------------------

Specify the maximum size of an entry in bytes. Attempts to store an
entry larger than this size will be rejected with the error
LDAP_ADMINLIMIT_EXCEEDED. The default is 0, which is unlimited.

5.2.7.6. olcDbMaxReaders: <integer>
-----------------------------------

This directive specifies the maximum number of threads that may have
concurrent read access to the database. Tools such as slapcat count as
a single thread, in addition to threads in any active slapd processes.
The default is 126.

5.2.7.7. olcDbMaxSize: <bytes>
------------------------------

This directive specifies the maximum size of the database in bytes. A
memory map of this size is allocated at startup time and the database
will not be allowed to grow beyond this size. The default is 10485760
bytes (10MB). This setting may be changed upward if the configured
limit needs to be increased.

Note: It is important to set this to as large a value as possible,
(relative to anticipated growth of the actual data over time) since
growing the size later may not be practical when the system is under
heavy load.

5.2.7.8. olcDbMode: { <octal> | <symbolic> }
--------------------------------------------

This directive specifies the file protection mode that newly created
database index files should have. This can be in the form 0600 or
-rw-------

Default:

        olcDbMode: 0600

5.2.7.9. olcDbMultival: { <attrlist> | default } <integer> hi,<integer> lo
--------------------------------------------------------------------------

Specify the number of values for which a multivalued attribute is
stored in a separate table. Normally entries are stored as a single
blob inside the database. When an entry gets very large or contains
attributes with a very large number of values, modifications on that
entry may get very slow. Splitting the large attributes out to a
separate table can improve the performance of modification operations.
The threshold is specified as a pair of integers. If the number of
values exceeds the hi threshold the values will be split out. If a
modification deletes enough values to bring an attribute below the lo
threshold the values will be removed from the separate table and
merged back into the main entry blob. The threshold can be set for a
specific list of attributes, or the default can be configured for all
other attributes. The default value for both hi and lo thresholds is
UINT_MAX, which keeps all attributes in the main blob.

In addition to increasing write performance of operations the use of
multival can also decrease fragmentation of the primary MDB database.

5.2.7.10. olcDbRtxnsize: <entries>
----------------------------------

This directive specifies the maximum number of entries to process in a
single read transaction when executing a large search. Long-lived read
transactions prevent old database pages from being reused in write
transactions, and so can cause significant growth of the database file
when there is heavy write traffic. This setting causes the read
transaction in large searches to be released and reacquired after the
given number of entries has been read, to give writers the opportunity
to reclaim old database pages. The default is 10000.

5.2.7.11. olcDbSearchStack: <integer>
-------------------------------------

Specify the depth of the stack used for search filter evaluation.
Search filters are evaluated on a stack to accommodate nested AND / OR
clauses. An individual stack is allocated for each server thread. The
depth of the stack determines how complex a filter can be evaluated
without requiring any additional memory allocation. Filters that are
nested deeper than the search stack depth will cause a separate stack
to be allocated for that particular search operation. These separate
allocations can have a major negative impact on server performance,
but specifying too much stack will also consume a great deal of
memory. Each search uses 512K bytes per level on a 32-bit machine, or
1024K bytes per level on a 64-bit machine. The default stack depth is
16, thus 8MB or 16MB per thread is used on 32 and 64 bit machines,
respectively. Also the 512KB size of a single stack slot is set by a
compile-time constant which may be changed if needed; the code must be
recompiled for the change to take effect.

Default:

        olcDbSearchStack: 16

5.2.7.12. olcDbNosync: { TRUE | FALSE }
---------------------------------------

This directive causes on-disk database contents to not be immediately
synchronized with in memory changes upon change.  Setting this option
to TRUE may improve performance at the expense of data integrity.

5.2.7.13. Sample Entry
----------------------

dn: olcDatabase=mdb,cn=config
objectClass: olcDatabaseConfig
objectClass: olcMdbConfig
olcDatabase: mdb
olcSuffix: dc=example,dc=com
olcDbDirectory: /usr/local/var/openldap-data
olcDbIndex: objectClass eq

5.3. Configuration Example
--------------------------

The following is an example configuration, interspersed with
explanatory text. It defines two databases to handle different parts
of the X.500 tree; both are MDB database instances. The line numbers
shown are provided for reference only and are not included in the
actual file. First, the global configuration section:

  1.    # example config file - global configuration entry
  2.    dn: cn=config
  3.    objectClass: olcGlobal
  4.    cn: config
  5.    olcReferral: ldap://root.openldap.org
  6.

Line 1 is a comment. Lines 2-4 identify this as the global
configuration entry. The olcReferral: directive on line 5 means that
queries not local to one of the databases defined below will be
referred to the LDAP server running on the standard port (389) at the
host root.openldap.org. Line 6 is a blank line, indicating the end of
this entry.

  7.    # internal schema
  8.    dn: cn=schema,cn=config
  9.    objectClass: olcSchemaConfig
 10.    cn: schema
 11.

Line 7 is a comment. Lines 8-10 identify this as the root of the
schema subtree. The actual schema definitions in this entry are
hardcoded into slapd so no additional attributes are specified here.
Line 11 is a blank line, indicating the end of this entry.

 12.    # include the core schema
 13.    include: file:///usr/local/etc/openldap/schema/core.ldif
 14.

Line 12 is a comment. Line 13 is an LDIF include directive which
accesses the core schema definitions in LDIF format. Line 14 is a
blank line.

Next comes the database definitions. The first database is the special
frontend database whose settings are applied globally to all the other
databases.

 15.    # global database parameters
 16.    dn: olcDatabase=frontend,cn=config
 17.    objectClass: olcDatabaseConfig
 18.    objectClass: olcFrontendConfig
 19.    olcDatabase: frontend
 20.    olcAccess: to * by * read
 21.

Line 15 is a comment. Lines 16-18 identify this entry as the global
database entry. Line 20 is a global access control. It applies to all
entries (after any applicable database-specific access controls). Line
21 is a blank line.

The next entry defines the config backend.

 22.    # set a rootpw for the config database so we can bind.
 23.    # deny access to everyone else.
 24.    dn: olcDatabase=config,cn=config
 25.    objectClass: olcDatabaseConfig
 26.    olcDatabase: config
 27.    olcRootPW: {SSHA}XKYnrjvGT3wZFQrDD5040US592LxsdLy
 28.    olcAccess: to * by * none
 29.

Lines 22-23 are comments. Lines 24-26 identify this entry as the
config database entry. Line 27 defines the super-user password for
this database. (The DN defaults to "cn=config".) Line 28 denies all
access to this database, so only the super-user will be able to access
it. (This is already the default access on the config database. It is
just listed here for illustration, and to reiterate that unless a
means to authenticate as the super-user is explicitly configured, the
config database will be inaccessible.)

Line 29 is a blank line.

The next entry defines an MDB backend that will handle queries for
things in the "dc=example,dc=com" portion of the tree. Indices are to
be maintained for several attributes, and the userPassword attribute
is to be protected from unauthorized access.

 30.    # MDB definition for example.com
 31.    dn: olcDatabase=mdb,cn=config
 32.    objectClass: olcDatabaseConfig
 33.    objectClass: olcMdbConfig
 34.    olcDatabase: mdb
 35.    olcSuffix: dc=example,dc=com
 36.    olcDbDirectory: /usr/local/var/openldap-data
 37.    olcRootDN: cn=Manager,dc=example,dc=com
 38.    olcRootPW: secret
 39.    olcDbIndex: uid pres,eq
 40.    olcDbIndex: cn,sn pres,eq,approx,sub
 41.    olcDbIndex: objectClass eq
 42.    olcAccess: to attrs=userPassword
 43.      by self write
 44.      by anonymous auth
 45.      by dn.base="cn=Admin,dc=example,dc=com" write
 46.      by * none
 47.    olcAccess: to *
 48.      by self write
 49.      by dn.base="cn=Admin,dc=example,dc=com" write
 50.      by * read
 51.

Line 30 is a comment. Lines 31-34 identify this entry as a MDB
database configuration entry.  Line 35 specifies the DN suffix for
queries to pass to this database. Line 36 specifies the directory in
which the database files will live.

Lines 37 and 38 identify the database super-user entry and associated
password. This entry is not subject to access control or size or time
limit restrictions.

Lines 39 through 41 indicate the indices to maintain for various
attributes.

Lines 42 through 50 specify access control for entries in this
database. For all applicable entries, the userPassword attribute is
writable by the entry itself and by the "admin" entry.  It may be used
for authentication/authorization purposes, but is otherwise not
readable. All other attributes are writable by the entry and the
"admin" entry, but may be read by all users (authenticated or not).

Line 51 is a blank line, indicating the end of this entry.

The next entry defines another MDB database. This one handles queries
involving the dc=example,dc=net subtree but is managed by the same
entity as the first database.  Note that without line 61, the read
access would be allowed due to the global access rule at line 20.

 52.    # MDB definition for example.net
 53.    dn: olcDatabase=mdb,cn=config
 54.    objectClass: olcDatabaseConfig
 55.    objectClass: olcMdbConfig
 56.    olcDatabase: mdb
 57.    olcSuffix: dc=example,dc=net
 58.    olcDbDirectory: /usr/local/var/openldap-data-net
 59.    olcRootDN: cn=Manager,dc=example,dc=com
 60.    olcDbIndex: objectClass eq
 61.    olcAccess: to * by users read

5.4. Converting old style slapd.conf(5) file to cn=config format
----------------------------------------------------------------

Before converting to the cn=config format you should make sure that
the config backend is properly configured in your existing config
file. While the config backend is always present inside slapd, by
default it is only accessible by its rootDN, and there are no default
credentials assigned so unless you explicitly configure a means to
authenticate to it, it will be unusable.

If you do not already have a database config section, add something
like this to the end of slapd.conf

 database config
 rootpw VerySecret

Note: Since the config backend can be used to load arbitrary code into
the slapd process, it is extremely important to carefully guard
whatever credentials are used to access it. Since simple passwords are
vulnerable to password guessing attacks, it is usually better to omit
the rootpw and only use SASL authentication for the config rootDN.

An existing slapd.conf(5) file can be converted to the new format
using slaptest(8) or any of the slap tools:

        slaptest -f /usr/local/etc/openldap/slapd.conf -F /usr/local/etc/openldap/slapd.d

Test that you can access entries under cn=config using the default
rootdn and the rootpw configured above:

        ldapsearch -x -D cn=config -w VerySecret -b cn=config

You can then discard the old slapd.conf(5) file. Make sure to launch
slapd(8) with the -F option to specify the configuration directory if
you are not using the default directory path.

Note: When converting from the slapd.conf format to slapd.d format,
any included files will also be integrated into the resulting
configuration database.

5.5. Recovering from a broken configuration
-------------------------------------------

If the server using cn=config does not start, either because the
configuration does not represent the current version or because it has
been corrupted, these actions are available, in the order of
decreasing preference.

Make sure you have made a backup of the "broken" version before you
attempt any of these:

5.5.1. Generate an ldif version of the configuration database and reload from that
----------------------------------------------------------------------------------

Most of the time, the configuration can be parsed and a text version
generated with slapcat(8):

 slapcat -F /usr/local/etc/openldap/slapd.d -n0 -l extracted_config.ldif

After you have backed up and removed the old configuration database
contents, this output ldif can be hand-edited to adjust or remove the
offending entries and imported again:

 slapadd -F /usr/local/etc/openldap/slapd.d -l updated_config.ldif
 slaptest -F /usr/local/etc/openldap/slapd.d

5.5.2. Modify config in-place
-----------------------------

If the configuration can be parsed and you know exactly what you need
to do, you can use slapmodify(8) to effect the required changes
directly:

 slapmodify -F /usr/local/etc/openldap/slapd.d
 dn: ..., cn=config
 changetype: ...
 ...

5.5.3. Recover with plain back-ldif
-----------------------------------

If the configuration contains items that slapd(8) cannot process as a
cn=config database at all, the last resort is to disable schema
checking and operate on it as a regular back-ldif database. This might
cease to work with future versions of OpenLDAP without notice, attempt
this only when all of the above fail.

First, create a directory to serve as the hosting DB and create the
structure:

 mkdir ./recovery ./recovery/cn=recovery
 cp /usr/local/etc/openldap/slapd.d/cn=config.ldif ./recovery/cn=recovery
 cp -r /usr/local/etc/openldap/slapd.d/cn=config ./recovery/cn=recovery

Or, if you have already backed up your old configuration, you can
symlink it into place:

 mkdir ./recovery
 ln -s /usr/local/etc/openldap/slapd.d ./recovery/cn=recovery

Next, create a trivial slapd.conf(5) to access the new database:

 database ldif
 suffix cn=recovery
 directory ./recovery/

Note the change of suffix, cn=config is hardcoded to correspond to an
active config database, so we have to home it one level deeper - at
cn=config,cn=recovery.

Now you can use slapmodify(8) to modify the database, it is most
likely you will need to run with schema checking disabled:

 slapmodify -f ./recovery.conf -s

You can test the validity of your config with slaptest(8):

 slaptest -F ./recovery/cn=recovery

And generate a full ldif with slapcat(8):

 slapcat -F ./recovery/cn=recovery -n0


6. The slapd Configuration File
===============================

This chapter describes configuring slapd(8) via the slapd.conf(5)
configuration file.  slapd.conf(5) has been deprecated and should only
be used if your site requires one of the backends that hasn't yet been
updated to work with the newer slapd-config(5) system.  Configuring
slapd(8) via slapd-config(5) is described in the previous chapter.

The slapd.conf(5) file is normally installed in the
/usr/local/etc/openldap directory.  An alternate configuration file
location can be specified via a command-line option to slapd(8).

6.1. Configuration File Format
------------------------------

The slapd.conf(5) file consists of three types of configuration
information: global, backend specific, and database specific.  Global
information is specified first, followed by information associated
with a particular backend type, which is then followed by information
associated with a particular database instance.  Global directives can
be overridden in backend and/or database directives, and backend
directives can be overridden by database directives.

Blank lines and comment lines beginning with a '#' character are
ignored.  If a line begins with whitespace, it is considered a
continuation of the previous line (even if the previous line is a
comment).

The general format of slapd.conf is as follows:

        # global configuration directives
        <global config directives>

        # backend definition
        backend <typeA>
        <backend-specific directives>

        # first database definition & config directives
        database <typeA>
        <database-specific directives>

        # second database definition & config directives
        database <typeB>
        <database-specific directives>

        # second database definition & config directives
        database <typeA>
        <database-specific directives>

        # subsequent backend & database definitions & config directives
        ...

A configuration directive may take arguments.  If so, they are
separated by whitespace.  If an argument contains whitespace, the
argument should be enclosed in double quotes "like this". If an
argument contains a double quote or a backslash character `\', the
character should be preceded by a backslash character `\'.

The distribution contains an example configuration file that will be
installed in the /usr/local/etc/openldap directory. A number of files
containing schema definitions (attribute types and object classes) are
also provided in the /usr/local/etc/openldap/schema directory.

6.2. Configuration File Directives
----------------------------------

This section details commonly used configuration directives.  For a
complete list, see the slapd.conf(5) manual page.  This section
separates the configuration file directives into global,
backend-specific and data-specific categories, describing each
directive and its default value (if any), and giving an example of its
use.

6.2.1. Global Directives
------------------------

Directives described in this section apply to all backends and
databases unless specifically overridden in a backend or database
definition.  Arguments that should be replaced by actual text are
shown in brackets <>.

6.2.1.1. access to <what> [ by <who> [<accesslevel>] [<control>] ]+
-------------------------------------------------------------------

This directive grants access (specified by <accesslevel>) to a set of
entries and/or attributes (specified by <what>) by one or more
requestors (specified by <who>).  See the Access Control section of
this guide for basic usage.

Note: If no access directives are specified, the default access
control policy, access to * by * read, allows all both authenticated
and anonymous users read access.

6.2.1.2. attributetype <RFC4512 Attribute Type Description>
-----------------------------------------------------------

This directive defines an attribute type. Please see the Schema
Specification chapter for information regarding how to use this
directive.

6.2.1.3. idletimeout <integer>
------------------------------

Specify the number of seconds to wait before forcibly closing an idle
client connection.  An idletimeout of 0, the default, disables this
feature.

6.2.1.4. include <filename>
---------------------------

This directive specifies that slapd should read additional
configuration information from the given file before continuing with
the next line of the current file. The included file should follow the
normal slapd config file format.  The file is commonly used to include
files containing schema specifications.

Note: You should be careful when using this directive - there is no
small limit on the number of nested include directives, and no loop
detection is done.

6.2.1.5. loglevel <level>
-------------------------

This directive specifies the level at which log statements and
operation statistics should be sent to syslog (currently logged to the
syslogd(8) LOG_LOCAL4 facility). You must have configured OpenLDAP
--enable-debug (the default) for this to work, except for the two
statistics levels, which are always enabled. Log levels may be
specified as integers or by keyword. Multiple log levels may be used
and the levels are additive. The possible values for <integer> are:

Table 6.1: Logging Levels

                 Level Keyword                 Description
...................... ....................... ...................... 
                    -1 any                     enable all debugging
                     0                         no debugging
                     1 (0x1 trace)             trace function calls
                     2 (0x2 packets)           debug packet handling
                     4 (0x4 args)              heavy trace debugging
                     8 (0x8 conns)             connection management
                    16 (0x10 BER)              print out packets sent
                                               and received
                    32 (0x20 filter)           search filter
                                               processing
                    64 (0x40 config)           configuration
                                               processing
                   128 (0x80 ACL)              access control list
                                               processing
                   256 (0x100 stats)           stats log
                                               connections/operations/results
                   512 (0x200 stats2)          stats log entries sent
                  1024 (0x400 shell)           print communication
                                               with shell backends
                  2048 (0x800 parse)           print entry parsing
                                               debugging
                 16384 (0x4000 sync)           syncrepl consumer
                                               processing
                 32768 (0x8000 none)           only messages that get
                                               logged regardless of
                                               configured log level

The desired log level can be input as a single integer that combines
the (ORed) desired levels, both in decimal or in hexadecimal notation,
as a list of integers (that are ORed internally), or as a list of the
names that are shown between brackets, such that

                loglevel 129
                loglevel 0x81
                loglevel 128 1
                loglevel 0x80 0x1
                loglevel acl trace

are equivalent.

Examples:

 loglevel -1

This will enable all log levels.

 loglevel conns filter

Just log the connection and search filter processing.

 loglevel none

Log those messages that are logged regardless of the configured
loglevel. This differs from setting the log level to 0, when no
logging occurs. At least the None level is required to have high
priority messages logged.

Default:

 loglevel stats

Basic stats logging is configured by default.

6.2.1.6. objectclass <RFC4512 Object Class Description>
-------------------------------------------------------

This directive defines an object class. Please see the Schema
Specification chapter for information regarding how to use this
directive.

6.2.1.7. referral <URI>
-----------------------

This directive specifies the referral to pass back when slapd cannot
find a local database to handle a request.

Example:

        referral ldap://root.openldap.org

This will refer non-local queries to the global root LDAP server at
the OpenLDAP Project. Smart LDAP clients can re-ask their query at
that server, but note that most of these clients are only going to
know how to handle simple LDAP URLs that contain a host part and
optionally a distinguished name part.

6.2.1.8. sizelimit <integer>
----------------------------

This directive specifies the maximum number of entries to return from
a search operation.

Default:

        sizelimit 500

See the Limits section of this guide and slapd.conf(5) for more
details.

6.2.1.9. timelimit <integer>
----------------------------

This directive specifies the maximum number of seconds (in real time)
slapd will spend answering a search request. If a request is not
finished in this time, a result indicating an exceeded timelimit will
be returned.

Default:

        timelimit 3600

See the Limits section of this guide and slapd.conf(5) for more
details.

6.2.2. General Backend Directives
---------------------------------

Directives in this section apply only to the backend in which they are
defined. They are supported by every type of backend. Backend
directives apply to all databases instances of the same type and,
depending on the directive, may be overridden by database directives.

6.2.2.1. backend <type>
-----------------------

This directive marks the beginning of a backend declaration. <type>
should be one of the supported backend types listed in Table 6.2.

Table 6.2: Database Backends

Types                              Description
.................................. .................................. 
asyncmet                           a Asynchronous Metadirectory
                                   backend
config                             Slapd configuration backend
dnssrv                             DNS SRV backend
ldap                               Lightweight Directory Access
                                   Protocol (Proxy) backend
ldif                               Lightweight Data Interchange
                                   Format backend
mdb                                Memory-Mapped DB backend
meta                               Metadirectory backend
monitor                            Monitor backend
null                               Null backend
passwd                             Provides read-only access to
                                   passwd(5)
perl                               Perl Programmable backend
relay                              Relay backend
sock                               Socket backend
sql                                SQL Programmable backend
wt                                 WiredTiger backend

Example:

        backend mdb
        idlexp 16

This marks the beginning of a new MDB backend definition. At present,
only back-mdb implements any options of this type, so this setting is
not needed for any other backends.

6.2.3. General Database Directives
----------------------------------

Directives in this section apply only to the database in which they
are defined. They are supported by every type of database.

6.2.3.1. database <type>
------------------------

This directive marks the beginning of a database instance declaration.
<type> should be one of the supported backend types listed in Table
6.2.

Example:

        database mdb

This marks the beginning of a new MDB database instance declaration.

6.2.3.2. limits <selector> <limit> [<limit> [...]]
--------------------------------------------------

Specify time and size limits based on the operation's initiator or
base DN.

See the Limits section of this guide and slapd.conf(5) for more
details.

6.2.3.3. readonly { on | off }
------------------------------

This directive puts the database into "read-only" mode. Any attempts
to modify the database will return an "unwilling to perform" error. 
If set on a consumer, modifications sent by syncrepl will still occur.

Default:

        readonly off

6.2.3.4. rootdn <DN>
--------------------

This directive specifies the DN that is not subject to access control
or administrative limit restrictions for operations on this database. 
The DN need not refer to an entry in this database or even in the
directory. The DN may refer to a SASL identity.

Entry-based Example:

        rootdn "cn=Manager,dc=example,dc=com"

SASL-based Example:

        rootdn "uid=root,cn=example.com,cn=digest-md5,cn=auth"

See the SASL Authentication section for information on SASL
authentication identities.

6.2.3.5. rootpw <password>
--------------------------

This directive can be used to specifies a password for the DN for the
rootdn (when the rootdn is set to a DN within the database).

Example:

        rootpw secret

It is also permissible to provide hash of the password in RFC2307
form.  slappasswd(8) may be used to generate the password hash.

Example:

        rootpw {SSHA}ZKKuqbEKJfKSXhUbHG3fG8MDn9j1v4QN

The hash was generated using the command slappasswd -s secret.

6.2.3.6. suffix <dn suffix>
---------------------------

This directive specifies the DN suffix of queries that will be passed
to this backend database. Multiple suffix lines can be given, and at
least one is required for each database definition.

Example:

        suffix "dc=example,dc=com"

Queries with a DN ending in "dc=example,dc=com" will be passed to this
backend.

Note: When the backend to pass a query to is selected, slapd looks at
the suffix line(s) in each database definition in the order they
appear in the file. Thus, if one database suffix is a prefix of
another, it must appear after it in the config file.

6.2.3.7. syncrepl
-----------------

        syncrepl rid=<replica ID>
                provider=ldap[s]://<hostname>[:port]
                searchbase=<base DN>
                [type=refreshOnly|refreshAndPersist]
                [interval=dd:hh:mm:ss]
                [retry=[<retry interval> <# of retries>]+]
                [filter=<filter str>]
                [scope=sub|one|base]
                [attrs=<attr list>]
                [exattrs=<attr list>]
                [attrsonly]
                [sizelimit=<limit>]
                [timelimit=<limit>]
                [schemachecking=on|off]
                [network-timeout=<seconds>]
                [timeout=<seconds>]
                [bindmethod=simple|sasl]
                [binddn=<DN>]
                [saslmech=<mech>]
                [authcid=<identity>]
                [authzid=<identity>]
                [credentials=<passwd>]
                [realm=<realm>]
                [secprops=<properties>]
                [keepalive=<idle>:<probes>:<interval>]
                [starttls=yes|critical]
                [tls_cert=<file>]
                [tls_key=<file>]
                [tls_cacert=<file>]
                [tls_cacertdir=<path>]
                [tls_reqcert=never|allow|try|demand]
                [tls_cipher_suite=<ciphers>]
                [tls_crlcheck=none|peer|all]
                [tls_protocol_min=<major>[.<minor>]]
                [suffixmassage=<real DN>]
                [logbase=<base DN>]
                [logfilter=<filter str>]
                [syncdata=default|accesslog|changelog]

This directive specifies the current database as a consumer of the
provider content by establishing the current slapd(8) as a replication
consumer site running a syncrepl replication engine. The provider
database is located at the replication provider site specified by the
provider parameter. The consumer database is kept up-to-date with the
provider content using the LDAP Content Synchronization protocol. See
RFC4533 for more information on the protocol.

The rid parameter is used for identification of the current syncrepl
directive within the replication consumer server, where <replica ID>
uniquely identifies the syncrepl specification described by the
current syncrepl directive. <replica ID> is non-negative and is no
more than three decimal digits in length.

The provider parameter specifies the replication provider site
containing the provider content as an LDAP URI. The provider parameter
specifies a scheme, a host and optionally a port where the provider
slapd instance can be found. Either a domain name or IP address may be
used for <hostname>. Examples are ldap://provider.example.com:389 or
ldaps://192.168.1.1:636. If <port> is not given, the standard LDAP
port number (389 or 636) is used. Note that the syncrepl uses a
consumer-initiated protocol, and hence its specification is located on
the consumer.

The content of the syncrepl consumer is defined using a search
specification as its result set. The consumer slapd will send search
requests to the provider slapd according to the search specification.
The search specification includes searchbase, scope, filter, attrs,
exattrs, attrsonly, sizelimit, and timelimit parameters as in the
normal search specification. The searchbase parameter has no default
value and must always be specified. The scope defaults to sub, the
filter defaults to (objectclass=*), attrs defaults to "*,+" to
replicate all user and operational attributes, and attrsonly is unset
by default. Both sizelimit and timelimit default to "unlimited", and
only positive integers or "unlimited" may be specified. The exattrs
option may also be used to specify attributes that should be omitted
from incoming entries.

The LDAP Content Synchronization protocol has two operation types:
refreshOnly and refreshAndPersist. The operation type is specified by
the type parameter. In the refreshOnly operation, the next
synchronization search operation is periodically rescheduled at an
interval time after each synchronization operation finishes. The
interval is specified by the interval parameter. It is set to one day
by default. In the refreshAndPersist operation, a synchronization
search remains persistent in the provider slapd instance. Further
updates to the provider will generate searchResultEntry to the
consumer slapd as the search responses to the persistent
synchronization search.

If an error occurs during replication, the consumer will attempt to
reconnect according to the retry parameter which is a list of the
<retry interval> and <# of retries> pairs. For example, retry="60 10
300 3" lets the consumer retry every 60 seconds for the first 10 times
and then retry every 300 seconds for the next three times before stop
retrying. + in <#  of retries> means indefinite number of retries
until success.

The schema checking can be enforced at the LDAP Sync consumer site by
turning on the schemachecking parameter. If it is turned on, every
replicated entry will be checked for its schema as the entry is stored
on the consumer. Every entry in the consumer should contain those
attributes required by the schema definition. If it is turned off,
entries will be stored without checking schema conformance. The
default is off.

The network-timeout parameter sets how long the consumer will wait to
establish a network connection to the provider.  Once a connection is
established, the timeout parameter determines how long the consumer
will wait for the initial Bind request to complete.  The defaults for
these parameters come from ldap.conf(5).

The binddn parameter gives the DN to bind as for the syncrepl searches
to the provider slapd. It should be a DN which has read access to the
replication content in the provider database.

The bindmethod is simple or sasl, depending on whether simple
password-based authentication or SASL authentication is to be used
when connecting to the provider slapd instance.

Simple authentication should not be used unless adequate data
integrity and confidentiality protections are in place (e.g. TLS or
IPsec). Simple authentication requires specification of binddn and
credentials parameters.

SASL authentication is generally recommended.  SASL authentication
requires specification of a mechanism using the saslmech parameter.
Depending on the mechanism, an authentication identity and/or
credentials can be specified using authcid and credentials,
respectively.  The authzid parameter may be used to specify an
authorization identity.

The realm parameter specifies a realm which a certain mechanisms
authenticate the identity within. The secprops parameter specifies
Cyrus SASL security properties.

The keepalive parameter sets the values of idle, probes, and interval
used to check whether a socket is alive;  idle is the number of
seconds a connection needs to remain idle before TCP starts sending
keepalive probes; probes is the maximum number of keepalive probes TCP
should send before dropping the connection; interval is interval in
seconds between individual keepalive probes.  Only some systems
support the customization of these values; the keepalive parameter is
ignored otherwise, and system-wide settings are used. For example,
keepalive="240:10:30" will send a keepalive probe 10 times, every 30
seconds, after 240 seconds of idle activity.  If no response to the
probes is received, the connection will be dropped.

The starttls parameter specifies use of the StartTLS extended
operation to establish a TLS session before authenticating to the
provider. If the critical argument is supplied, the session will be
aborted if the StartTLS request fails.  Otherwise the syncrepl session
continues without TLS.  The tls_reqcert setting defaults to "demand"
and the other TLS settings default to the same as the main slapd TLS
settings.

The suffixmassage parameter allows the consumer to pull entries from a
remote directory whose DN suffix differs from the local directory. The
portion of the remote entries' DNs that matches the searchbase will be
replaced with the suffixmassage DN.

Rather than replicating whole entries, the consumer can query logs of
data modifications.  This mode of operation is referred to as delta
syncrepl.  In addition to the above parameters, the logbase and
logfilter parameters must be set appropriately for the log that will
be used. The syncdata parameter must be set to either "accesslog" if
the log conforms to the slapo-accesslog(5) log format, or "changelog"
if the log conforms to the obsolete changelog format. If the syncdata
parameter is omitted or set to "default" then the log parameters are
ignored.

The syncrepl replication mechanism is supported by the mdb backend.

See the LDAP Sync Replication chapter of this guide for more
information on how to use this directive.

6.2.3.8. updateref <URL>
------------------------

This directive is only applicable in a replica (or shadow) slapd(8)
instance. It specifies the URL to return to clients which submit
update requests upon the replica. If specified multiple times, each
URL is provided.

Example:

        updateref       ldap://provider.example.net

6.2.4. MDB Backend Directives
-----------------------------

Directives in this category only apply to the MDB database backend.
They will apply to all "database mdb" instances in the configuration.
For a complete reference of MDB backend configuration directives, see
slapd-mdb(5).

6.2.4.1. idlexp <exponent>
--------------------------

Specify a power of 2 for the maximum size of an index slot. The
default is 16, yielding a maximum slot size of 2^16 or 65536. The
specified value must be in the range of 16-30.

This setting helps with the case where certain search filters are slow
to return results due to an index slot having collapsed to a range
value.  This occurs when the number of candidate entries that match
the filter for the index slot exceed the configured slot size.

If this setting is decreased on a server with existing MDB databases,
each db will immediately need its indices to be rebuilt while slapd is
offline with the "slapindex -q -t" command.

If this setting is increased on a server with existing MDB databases,
each db will need its indices rebuilt to take advantage of the change
for indices that have already been converted to ranges.

6.2.5. MDB Database Directives
------------------------------

Directives in this category only apply to the MDB database backend.
That is, they must follow a "database mdb" line and come before any
subsequent "backend" or "database" lines. For a complete reference of
MDB configuration directives, see slapd-mdb(5).

6.2.5.1. directory <directory>
------------------------------

This directive specifies the directory where the MDB files containing
the database and associated indices live.

Default:

        directory /usr/local/var/openldap-data

6.2.5.2. checkpoint <kbyte> <min>
---------------------------------

This directive specifies the frequency for flushing the database disk
buffers. This directive is only needed if the dbnosync option is TRUE.
The checkpoint will occur if either <kbyte> data has been written or
<min> minutes have passed since the last checkpoint. Both arguments
default to zero, in which case they are ignored. When the <min>
argument is non-zero, an internal task will run every <min> minutes to
perform the checkpoint. Note: currently the _kbyte_ setting is
unimplemented.

Example:

   checkpoint: 1024 10

6.2.5.3. dbnosync: { TRUE | FALSE }
-----------------------------------

This directive causes on-disk database contents to not be immediately
synchronized with in memory changes upon change.  Setting this option
to TRUE may improve performance at the expense of data integrity.

6.2.5.4. envflags: {nosync,nometasync,writemap,mapasync,nordahead}
------------------------------------------------------------------

This option specifies flags for finer-grained control of  the  LMDB 
library's operation.

o    nosync: This is exactly the same as the dbnosync directive.

o    nometasync: Flush the data on a commit, but skip the sync of the
     meta page. This mode is slightly faster than doing a full sync,
     but can potentially lose the last committed transaction if the
     operating system crashes. If both nometasync and nosync are set,
     the nosync flag takes precedence.

o    writemap: Use a writable memory map instead of just read-only.
     This speeds up write operations but makes the database vulnerable
     to corruption in case any bugs in slapd cause stray writes into
     the mmap region.

o    mapasync: When using a writable memory map and performing flushes
     on each commit, use an asynchronous flush instead of a
     synchronous flush (the default). This option has no effect if
     writemap has not been set. It also has no effect if nosync is
     set.

o    nordahead: Turn off file readahead. Usually the OS performs
     readahead on every read request. This usually boosts read
     performance but can be harmful to random access read performance
     if the system's memory is full and the DB is larger than RAM.
     This option is not implemented on Windows.

6.2.5.5. index: {<attrlist> | default} [pres,eq,approx,sub,none]
----------------------------------------------------------------

This directive specifies the indices to maintain for the given
attribute. If only an <attrlist> is given, the default indices are
maintained. The index keywords correspond to the common types of
matches that may be used in an LDAP search filter.

Example:

   index: default pres,eq
   index: uid
   index: cn,sn pres,eq,sub
   index: objectClass eq

The first line sets the default set of indices to maintain to present
and equality.  The second line causes the default (pres,eq) set of
indices to be maintained for the uid attribute type. The third line
causes present, equality, and substring indices to be maintained for
cn and sn attribute types.  The fourth line causes an equality index
for the objectClass attribute type.

There is no index keyword for inequality matches. Generally these
matches do not use an index. However, some attributes do support
indexing for inequality matches, based on the equality index.

A substring index can be more explicitly specified as subinitial,
subany, or subfinal, corresponding to the three possible components of
a substring match filter. A subinitial index only indexes substrings
that appear at the beginning of an attribute value. A subfinal index
only indexes substrings that appear at the end of an attribute value,
while subany indexes substrings that occur anywhere in a value.

Note that by default, setting an index for an attribute also affects
every subtype of that attribute. E.g., setting an equality index on
the name attribute causes cn, sn, and every other attribute that
inherits from name to be indexed.

By default, no indices are maintained.  It is generally advised that
minimally an equality index upon objectClass be maintained.

   index: objectClass eq

Additional indices should be configured corresponding to the most
common searches that are used on the database. Presence indexing
should not be configured for an attribute unless the attribute occurs
very rarely in the database, and presence searches on the attribute
occur very frequently during normal use of the directory. Most
applications don't use presence searches, so usually presence indexing
is not very useful.

6.2.5.6. maxentrysize: <bytes>
------------------------------

Specify the maximum size of an entry in bytes. Attempts to store an
entry larger than this size will be rejected with the error
LDAP_ADMINLIMIT_EXCEEDED. The default is 0, which is unlimited.

6.2.5.7. maxreaders: <integer>
------------------------------

This directive specifies the maximum number of threads that may have
concurrent read access to the database. Tools such as slapcat count as
a single thread, in addition to threads in any active slapd processes.
The default is 126.

6.2.5.8. maxsize: <bytes>
-------------------------

This directive specifies the maximum size of the database in bytes. A
memory map of this size is allocated at startup time and the database
will not be allowed to grow beyond this size. The default is 10485760
bytes (10MB). This setting may be changed upward if the configured
limit needs to be increased.

Note: It is important to set this to as large a value as possible,
(relative to anticipated growth of the actual data over time) since
growing the size later may not be practical when the system is under
heavy load.

6.2.5.9. mode: { <octal> | <symbolic> }
---------------------------------------

This directive specifies the file protection mode that newly created
database index files should have. This can be in the form 0600 or
-rw-------

Default:

   mode: 0600

6.2.5.10. multival: { <attrlist> | default } <integer> hi,<integer> lo
----------------------------------------------------------------------

Specify the number of values for which a multivalued attribute is
stored in a separate table. Normally entries are stored as a single
blob inside the database. When an entry gets very large or contains
attributes with a very large number of values, modifications on that
entry may get very slow. Splitting the large attributes out to a
separate table can improve the performance of modification operations.
The threshold is specified as a pair of integers. If the number of
values exceeds the hi threshold the values will be split out. If a
modification deletes enough values to bring an attribute below the lo
threshold the values will be removed from the separate table and
merged back into the main entry blob. The threshold can be set for a
specific list of attributes, or the default can be configured for all
other attributes. The default value for both hi and lo thresholds is
UINT_MAX, which keeps all attributes in the main blob.

In addition to increasing write performance of operations the use of
multival can also decrease fragmentation of the primary MDB database.

6.2.5.11. rtxnsize: <entries>
-----------------------------

This directive specifies the maximum number of entries to process in a
single read transaction when executing a large search. Long-lived read
transactions prevent old database pages from being reused in write
transactions, and so can cause significant growth of the database file
when there is heavy write traffic. This setting causes the read
transaction in large searches to be released and reacquired after the
given number of entries has been read, to give writers the opportunity
to reclaim old database pages. The default is 10000.

6.2.5.12. searchstack: <integer>
--------------------------------

Specify the depth of the stack used for search filter evaluation.
Search filters are evaluated on a stack to accommodate nested AND / OR
clauses. An individual stack is allocated for each server thread. The
depth of the stack determines how complex a filter can be evaluated
without requiring any additional memory allocation. Filters that are
nested deeper than the search stack depth will cause a separate stack
to be allocated for that particular search operation. These separate
allocations can have a major negative impact on server performance,
but specifying too much stack will also consume a great deal of
memory. Each search uses 512K bytes per level on a 32-bit machine, or
1024K bytes per level on a 64-bit machine. The default stack depth is
16, thus 8MB or 16MB per thread is used on 32 and 64 bit machines,
respectively. Also the 512KB size of a single stack slot is set by a
compile-time constant which may be changed if needed; the code must be
recompiled for the change to take effect.

Default:

   searchstack: 16

6.2.5.13. Sample Entry
----------------------

database mdb
suffix: "dc=example,dc=com"
directory: /usr/local/var/openldap-data
index: objectClass eq

6.3. Configuration File Example
-------------------------------

The following is an example configuration file, interspersed with
explanatory text. It defines two databases to handle different parts
of the X.500 tree; both are MDB database instances. The line numbers
shown are provided for reference only and are not included in the
actual file. First, the global configuration section:

  1.    # example config file - global configuration section
  2.    include /usr/local/etc/schema/core.schema
  3.    referral ldap://root.openldap.org
  4.    access to * by * read

Line 1 is a comment. Line 2 includes another config file which
contains core schema definitions. The referral directive on line 3
means that queries not local to one of the databases defined below
will be referred to the LDAP server running on the standard port (389)
at the host root.openldap.org.

Line 4 is a global access control.  It applies to all entries (after
any applicable database-specific access controls).

The next section of the configuration file defines a MDB backend that
will handle queries for things in the "dc=example,dc=com" portion of
the tree. The database is to be replicated to two replica slapds, one
on truelies, the other on judgmentday. Indices are to be maintained
for several attributes, and the userPassword attribute is to be
protected from unauthorized access.

  5.    # MDB definition for the example.com
  6.    database mdb
  7.    suffix "dc=example,dc=com"
  8.    directory /usr/local/var/openldap-data
  9.    rootdn "cn=Manager,dc=example,dc=com"
 10.    rootpw secret
 11.    # indexed attribute definitions
 12.    index uid pres,eq
 13.    index cn,sn pres,eq,approx,sub
 14.    index objectClass eq
 15.    # database access control definitions
 16.    access to attrs=userPassword
 17.        by self write
 18.        by anonymous auth
 19.        by dn.base="cn=Admin,dc=example,dc=com" write
 20.        by * none
 21.    access to *
 22.        by self write
 23.        by dn.base="cn=Admin,dc=example,dc=com" write
 24.        by * read

Line 5 is a comment. The start of the database definition is marked by
the database keyword on line 6. Line 7 specifies the DN suffix for
queries to pass to this database. Line 8 specifies the directory in
which the database files will live.

Lines 9 and 10 identify the database super-user entry and associated
password. This entry is not subject to access control or size or time
limit restrictions.

Lines 12 through 14 indicate the indices to maintain for various
attributes.

Lines 16 through 24 specify access control for entries in this
database. For all applicable entries, the userPassword attribute is
writable by the entry itself and by the "admin" entry.  It may be used
for authentication/authorization purposes, but is otherwise not
readable. All other attributes are writable by the entry and the
"admin" entry, but may be read by all users (authenticated or not).

The next section of the example configuration file defines another MDB
database. This one handles queries involving the dc=example,dc=net
subtree but is managed by the same entity as the first database.  Note
that without line 39, the read access would be allowed due to the
global access rule at line 4.

 33.    # MDB definition for example.net
 34.    database mdb
 35.    suffix "dc=example,dc=net"
 36.    directory /usr/local/var/openldap-data-net
 37.    rootdn "cn=Manager,dc=example,dc=com"
 38.    index objectClass eq
 39.    access to * by users read


7. Running slapd
================

slapd(8) is designed to be run as a standalone service.  This allows
the server to take advantage of caching, manage concurrency issues
with underlying databases, and conserve system resources. Running from
inetd(8) is NOT an option.

7.1. Command-Line Options
-------------------------

slapd(8) supports a number of command-line options as detailed in the
manual page.  This section details a few commonly used options.

        -f <filename>

This option specifies an alternate configuration file for slapd. The
default is normally /usr/local/etc/openldap/slapd.conf.

        -F <slapd-config-directory>

Specifies the slapd configuration directory. The default is
/usr/local/etc/openldap/slapd.d.

If both -f and -F are specified, the config file will be read and
converted to config directory format and written to the specified
directory. If neither option is specified, slapd will attempt to read
the default config directory before trying to use the default config
file. If a valid config directory exists then the default config file
is ignored. All of the slap tools that use the config options observe
this same behavior.

        -h <URLs>

This option specifies alternative listener configurations.  The
default is ldap:/// which implies LDAP over TCP on all interfaces on
the default LDAP port 389.  You can specify specific host-port pairs
or other protocol schemes (such as ldaps:// or ldapi://). slapd
supports the HAProxy proxy protocol version 2, which allows a load
balancer or proxy server to provide the remote client IP address to
slapd to be used for access control or logging. Listeners configured
using either pldap:/// or pldaps:/// URLS will only accept connections
that include the necessary proxy protocol header. Connections to the
ports used by these listeners should be restricted at the network
level to only trusted load balancers or proxies to avoid spoofing of
client IP addresses by third parties.

URL                    Protocol                Transport
...................... ....................... ...................... 
ldap:///               LDAP                    TCP port 389
pldap:///              proxied LDAP            TCP port 389
ldaps:///              LDAP over SSL           TCP port 636
pldaps:///             proxied LDAP over SSL   TCP port 636
ldapi:///              LDAP                    IPC (Unix-domain
                                               socket)

For example, -h "ldaps:// ldap://127.0.0.1:666" will create two
listeners: one for the (non-standard) ldaps:// scheme on all
interfaces on the default ldaps:// port 636, and one for the standard
ldap:// scheme on the localhost (loopback) interface on port 666. 
Hosts may be specified using using hostnames or IPv4 or IPv6
addresses.  Port values must be numeric.

For LDAP over IPC, the pathname of the Unix-domain socket can be
encoded in the URL. Note that directory separators must be
URL-encoded, like any other characters that are special to URLs. Thus
the socket /usr/local/var/ldapi must be encoded as

        ldapi://%2Fusr%2Flocal%2Fvar%2Fldapi

ldapi: is described in detail in Using LDAP Over IPC Mechanisms
[Chu-LDAPI]

Note that the ldapi:/// transport is not widely implemented:
non-OpenLDAP clients may not be able to use it.

        -n <service-name>

This option specifies the service name used for logging and other
purposes. The default service name is slapd.

        -l <syslog-local-user>

This option specifies the local user for the syslog(8) facility. 
Values can be LOCAL0, LOCAL1, LOCAL2, ..., and LOCAL7.  The default is
LOCAL4.  This option may not be supported on all systems.

        -u user -g group

These options specify the user and group, respectively, to run as. 
user can be either a user name or uid.  group can be either a group
name or gid.

        -r directory

This option specifies a run-time directory.  slapd will chroot(2) to
this directory after opening listeners but before reading any
configuration files or initializing any backends.



        -d <level> | ?

This option sets the slapd debug level to <level>. When level is a `?'
character, the various debugging levels are printed and slapd exits,
regardless of any other options you give it. Current debugging levels
are

Table 7.1: Debugging Levels

                 Level Keyword                 Description
...................... ....................... ...................... 
                    -1 any                     enable all debugging
                     0                         no debugging
                     1 (0x1 trace)             trace function calls
                     2 (0x2 packets)           debug packet handling
                     4 (0x4 args)              heavy trace debugging
                     8 (0x8 conns)             connection management
                    16 (0x10 BER)              print out packets sent
                                               and received
                    32 (0x20 filter)           search filter
                                               processing
                    64 (0x40 config)           configuration
                                               processing
                   128 (0x80 ACL)              access control list
                                               processing
                   256 (0x100 stats)           stats log
                                               connections/operations/results
                   512 (0x200 stats2)          stats log entries sent
                  1024 (0x400 shell)           print communication
                                               with shell backends
                  2048 (0x800 parse)           print entry parsing
                                               debugging
                 16384 (0x4000 sync)           syncrepl consumer
                                               processing
                 32768 (0x8000 none)           only messages that get
                                               logged whatever log
                                               level is set

You may enable multiple levels by specifying the debug option once for
each desired level.  Or, since debugging levels are additive, you can
do the math yourself. That is, if you want to trace function calls and
watch the config file being processed, you could set level to the sum
of those two levels (in this case,  -d 65).  Or, you can let slapd do
the math, (e.g.  -d 1 -d 64).  Consult <ldap_log.h> for more details.

Note: slapd must have been compiled with --enable-debug, which is the
default, for any debugging information other than the stats and stats2
levels to be available as options.

7.2. Starting slapd
-------------------

In general, slapd is run like this:

        /usr/local/libexec/slapd [<option>]*

where /usr/local/libexec is determined by configure and <option> is
one of the options described above (or in slapd(8)). Unless you have
specified a debugging level (including level 0), slapd will
automatically fork and detach itself from its controlling terminal and
run in the background.

7.3. Stopping slapd
-------------------

To kill off slapd(8) safely, you should give a command like this

        kill -INT `cat /usr/local/var/slapd.pid`

where /usr/local/var is determined by configure.

Killing slapd by a more drastic method may cause information loss or
database corruption.


8. Access Control
=================

8.1. Introduction
-----------------

As the directory gets populated with more and more data of varying
sensitivity, controlling the kinds of access granted to the directory
becomes more and more critical. For instance, the directory may
contain data of a confidential nature that you may need to protect by
contract or by law. Or, if using the directory to control access to
other services, inappropriate access to the directory may create
avenues of attack to your sites security that result in devastating
damage to your assets.

Access to your directory can be configured via two methods, the first
using The slapd Configuration File and the second using the
slapd-config(5) format (Configuring slapd).

The default access control policy is allow read by all clients.
Regardless of what access control policy is defined, the rootdn is
always allowed full rights (i.e. auth, search, compare, read and
write) on everything and anything.

As a consequence, it's useless (and results in a performance penalty)
to explicitly list the rootdn among the <by> clauses.

The following sections will describe Access Control Lists in greater
depth and follow with some examples and recommendations. See
slapd.access(5) for complete details.

8.2. Access Control via Static Configuration
--------------------------------------------

Access to entries and attributes is controlled by the access
configuration file directive. The general form of an access line is:

    <access directive> ::= access to <what>
        [by <who> [<access>] [<control>] ]+
    <what> ::= * |
        [dn[.<basic-style>]=<regex> | dn.<scope-style>=<DN>]
        [filter=<ldapfilter>] [attrs=<attrlist>]
    <basic-style> ::= regex | exact
    <scope-style> ::= base | one | subtree | children
    <attrlist> ::= <attr> [val[.<basic-style>]=<regex>] | <attr> , <attrlist>
    <attr> ::= <attrname> | entry | children
    <who> ::= * | [anonymous | users | self
            | dn[.<basic-style>]=<regex> | dn.<scope-style>=<DN>]
        [dnattr=<attrname>]
        [group[/<objectclass>[/<attrname>][.<basic-style>]]=<regex>]
        [peername[.<basic-style>]=<regex>]
        [sockname[.<basic-style>]=<regex>]
        [domain[.<basic-style>]=<regex>]
        [sockurl[.<basic-style>]=<regex>]
        [set=<setspec>]
        [aci=<attrname>]
    <access> ::= [self]{<level>|<priv>}
    <level> ::= none | disclose | auth | compare | search | read | write | manage
    <priv> ::= {=|+|-}{m|w|r|s|c|x|d|0}+
    <control> ::= [stop | continue | break]

where the <what> part selects the entries and/or attributes to which
the access applies, the <who> part specifies which entities are
granted access, and the <access> part specifies the access granted.
Multiple <who> <access> <control> triplets are supported, allowing
many entities to be granted different access to the same set of
entries and attributes. Not all of these access control options are
described here; for more details see the slapd.access(5) man page.

8.2.1. What to control access to
--------------------------------

The <what> part of an access specification determines the entries and
attributes to which the access control applies.  Entries are commonly
selected in two ways: by DN and by filter.  The following qualifiers
select entries by DN:

    to *
    to dn[.<basic-style>]=<regex>
    to dn.<scope-style>=<DN>

The first form is used to select all entries.  The second form may be
used to select entries by matching a regular expression against the
target entry's normalized DN.   (The second form is not discussed
further in this document.)  The third form is used to select entries
which are within the requested scope of DN.  The <DN> is a string
representation of the Distinguished Name, as described in RFC4514.

The scope can be either base, one, subtree, or children.  Where base
matches only the entry with provided DN, one matches the entries whose
parent is the provided DN, subtree matches all entries in the subtree
whose root is the provided DN, and children matches all entries under
the DN (but not the entry named by the DN).

For example, if the directory contained entries named:

    0: o=suffix
    1: cn=Manager,o=suffix
    2: ou=people,o=suffix
    3: uid=kdz,ou=people,o=suffix
    4: cn=addresses,uid=kdz,ou=people,o=suffix
    5: uid=hyc,ou=people,o=suffix

Then:

     dn.base="ou=people,o=suffix" match 2;

     dn.one="ou=people,o=suffix" match 3, and 5;

     dn.subtree="ou=people,o=suffix" match 2, 3, 4, and 5; and

     dn.children="ou=people,o=suffix" match 3, 4, and 5.

Entries may also be selected using a filter:

    to filter=<ldap filter>

where <ldap filter> is a string representation of an LDAP search
filter, as described in RFC4515.  For example:

    to filter=(objectClass=person)

Note that entries may be selected by both DN and filter by including
both qualifiers in the <what> clause.

    to dn.one="ou=people,o=suffix" filter=(objectClass=person)

Attributes within an entry are selected by including a comma-separated
list of attribute names in the <what> selector:

    attrs=<attribute list>

A specific value of an attribute is selected by using a single
attribute name and also using a value selector:

    attrs=<attribute> val[.<style>]=<regex>

There are two special pseudo attributes entry and children.  To read
(and hence return) a target entry, the subject must have read access
to the target's entry attribute.  To perform a search, the subject
must have search access to the search base's entry attribute. To add
or delete an entry, the subject must have write access to the entry's
entry attribute AND must have write access to the entry's parent's
children attribute.  To rename an entry, the subject must have write
access to entry's entry attribute AND have write access to both the
old parent's and new parent's children attributes.  The complete
examples at the end of this section should help clear things up.

Lastly, there is a special entry selector "*" that is used to select
any entry.  It is used when no other <what> selector has been
provided.  It's equivalent to "dn=.*"

8.2.2. Who to grant access to
-----------------------------

The <who> part identifies the entity or entities being granted access.
Note that access is granted to "entities" not "entries." The following
table summarizes entity specifiers:

Table 6.3: Access Entity Specifiers

Specifier                          Entities
.................................. .................................. 
*                                  All, including anonymous and
                                   authenticated users
anonymous                          Anonymous (non-authenticated)
                                   users
users                              Authenticated users
self                               User associated with target entry
dn[.<basic-style>]=<regex>         Users matching a regular
                                   expression
dn.<scope-style>=<DN>              Users within scope of a DN

The DN specifier behaves much like <what> clause DN specifiers.

Other control factors are also supported.  For example, a <who> can be
restricted by an entry listed in a DN-valued attribute in the entry to
which the access applies:

    dnattr=<dn-valued attribute name>

The dnattr specification is used to give access to an entry whose DN
is listed in an attribute of the entry (e.g., give access to a group
entry to whoever is listed as the owner of the group entry).

Some factors may not be appropriate in all environments (or any). For
example, the domain factor relies on IP to domain name lookups. As
these can easily be spoofed, the domain factor should be avoided.

8.2.3. The access to grant
--------------------------

The kind of <access> granted can be one of the following:

Table 6.4: Access Levels

Level                               Privileges Description
...................... ....................... ...................... 
none =                                       0 no access
disclose =                                   d needed for information
                                               disclosure on error
auth =                                      dx needed to authenticate
                                               (bind)
compare =                                  cdx needed to compare
search =                                  scdx needed to apply search
                                               filters
read =                                   rscdx needed to read search
                                               results
write =                                 wrscdx needed to
                                               modify/rename
manage =                               mwrscdx needed to manage

Each level implies all lower levels of access. So, for example,
granting someone write access to an entry also grants them read,
search, compare, auth and disclose access.  However, one may use the
privileges specifier to grant specific permissions.

8.2.4. Access Control Evaluation
--------------------------------

When evaluating whether some requester should be given access to an
entry and/or attribute, slapd compares the entry and/or attribute to
the <what> selectors given in the configuration file. For each entry,
access controls provided in the database which holds the entry (or the
global access directives if not held in any database) apply first,
followed by the global access directives. However, when dealing with
an access list, because the global access list is effectively appended
to each per-database list, if the resulting list is non-empty then the
access list will end with an implicit access to * by * none directive.
If there are no access directives applicable to a backend, then a
default read is used.

Within this priority, access directives are examined in the order in
which they appear in the config file.  Slapd stops with the first
<what> selector that matches the entry and/or attribute. The
corresponding access directive is the one slapd will use to evaluate
access.

Next, slapd compares the entity requesting access to the <who>
selectors within the access directive selected above in the order in
which they appear. It stops with the first <who> selector that matches
the requester. This determines the access the entity requesting access
has to the entry and/or attribute.

Finally, slapd compares the access granted in the selected <access>
clause to the access requested by the client. If it allows greater or
equal access, access is granted. Otherwise, access is denied.

The order of evaluation of access directives makes their placement in
the configuration file important. If one access directive is more
specific than another in terms of the entries it selects, it should
appear first in the config file. Similarly, if one <who> selector is
more specific than another it should come first in the access
directive. The access control examples given below should help make
this clear.

8.2.5. Access Control Examples
------------------------------

The access control facility described above is quite powerful.  This
section shows some examples of its use for descriptive purposes.

A simple example:

    access to * by * read

This access directive grants read access to everyone.

    access to *
        by self write
        by anonymous auth
        by * read

This directive allows the user to modify their entry, allows anonymous
to authenticate against these entries, and allows all others to read
these entries.  Note that only the first by <who> clause which matches
applies.  Hence, the anonymous users are granted auth, not read.  The
last clause could just as well have been "by users read".

It is often desirable to restrict operations based upon the level of
protection in place.  The following shows how security strength
factors (SSF) can be used.

    access to *
        by ssf=128 self write
        by ssf=64 anonymous auth
        by ssf=64 users read

This directive allows users to modify their own entries if security
protections of strength 128 or better have been established, allows
authentication access to anonymous users, and read access when 64 or
better security protections have been established.  If a client has
not established sufficient security protections, the implicit by *
none clause would be applied.

The following example shows the use of a style specifiers to select
the entries by DN in two access directives where ordering is
significant.

    access to dn.children="dc=example,dc=com"
         by * search
    access to dn.children="dc=com"
         by * read

Read access is granted to entries under the dc=com subtree, except for
those entries under the dc=example,dc=com subtree, to which search
access is granted.  No access is granted to dc=com as neither access
directive matches this DN.  If the order of these access directives
was reversed, the trailing directive would never be reached, since all
entries under dc=example,dc=com are also under dc=com entries.

Also note that if no access to directive matches or no by <who>
clause, access is denied.  That is, every access to directive ends
with an implicit by * none clause. When dealing with an access list,
because the global access list is effectively appended to each
per-database list, if the resulting list is non-empty then the access
list will end with an implicit access to * by * none directive. If
there are no access directives applicable to a backend, then a default
read is used.

The next example again shows the importance of ordering, both of the
access directives and the by <who> clauses.  It also shows the use of
an attribute selector to grant access to a specific attribute and
various <who> selectors.

    access to dn.subtree="dc=example,dc=com" attrs=homePhone
        by self write
        by dn.children="dc=example,dc=com" search
        by peername.regex=IP=10\..+ read
    access to dn.subtree="dc=example,dc=com"
        by self write
        by dn.children="dc=example,dc=com" search
        by anonymous auth

This example applies to entries in the "dc=example,dc=com" subtree. To
all attributes except homePhone, an entry can write to itself, entries
under example.com entries can search by them, anybody else has no
access (implicit by * none) excepting for authentication/authorization
(which is always done anonymously).  The homePhone attribute is
writable by the entry, searchable by entries under example.com,
readable by clients connecting from network 10, and otherwise not
readable (implicit by * none).  All other access is denied by the
implicit access to * by * none.

Sometimes it is useful to permit a particular DN to add or remove
itself from an attribute. For example, if you would like to create a
group and allow people to add and remove only their own DN from the
member attribute, you could accomplish it with an access directive
like this:

    access to attrs=member,entry
         by dnattr=member selfwrite

The dnattr <who> selector says that the access applies to entries
listed in the member attribute. The selfwrite access selector says
that such members can only add or delete their own DN from the
attribute, not other values. The addition of the entry attribute is
required because access to the entry is required to access any of the
entry's attributes.

8.3. Access Control via Dynamic Configuration
---------------------------------------------

Access to slapd entries and attributes is controlled by the olcAccess
attribute, whose values are a sequence of access directives. The
general form of the olcAccess configuration is:

    olcAccess: <access directive>
    <access directive> ::= to <what>
        [by <who> [<access>] [<control>] ]+
    <what> ::= * |
        [dn[.<basic-style>]=<regex> | dn.<scope-style>=<DN>]
        [filter=<ldapfilter>] [attrs=<attrlist>]
    <basic-style> ::= regex | exact
    <scope-style> ::= base | one | subtree | children
    <attrlist> ::= <attr> [val[.<basic-style>]=<regex>] | <attr> , <attrlist>
    <attr> ::= <attrname> | entry | children
    <who> ::= * | [anonymous | users | self
            | dn[.<basic-style>]=<regex> | dn.<scope-style>=<DN>]
        [dnattr=<attrname>]
        [group[/<objectclass>[/<attrname>][.<basic-style>]]=<regex>]
        [peername[.<basic-style>]=<regex>]
        [sockname[.<basic-style>]=<regex>]
        [domain[.<basic-style>]=<regex>]
        [sockurl[.<basic-style>]=<regex>]
        [set=<setspec>]
        [aci=<attrname>]
    <access> ::= [self]{<level>|<priv>}
    <level> ::= none | disclose | auth | compare | search | read | write | manage
    <priv> ::= {=|+|-}{m|w|r|s|c|x|d|0}+
    <control> ::= [stop | continue | break]

where the <what> part selects the entries and/or attributes to which
the access applies, the <who> part specifies which entities are
granted access, and the <access> part specifies the access granted.
Multiple <who> <access> <control> triplets are supported, allowing
many entities to be granted different access to the same set of
entries and attributes. Not all of these access control options are
described here; for more details see the slapd.access(5) man page.

8.3.1. What to control access to
--------------------------------

The <what> part of an access specification determines the entries and
attributes to which the access control applies.  Entries are commonly
selected in two ways: by DN and by filter.  The following qualifiers
select entries by DN:

    to *
    to dn[.<basic-style>]=<regex>
    to dn.<scope-style>=<DN>

The first form is used to select all entries.  The second form may be
used to select entries by matching a regular expression against the
target entry's normalized DN.   (The second form is not discussed
further in this document.)  The third form is used to select entries
which are within the requested scope of DN.  The <DN> is a string
representation of the Distinguished Name, as described in RFC4514.

The scope can be either base, one, subtree, or children.  Where base
matches only the entry with provided DN, one matches the entries whose
parent is the provided DN, subtree matches all entries in the subtree
whose root is the provided DN, and children matches all entries under
the DN (but not the entry named by the DN).

For example, if the directory contained entries named:

    0: o=suffix
    1: cn=Manager,o=suffix
    2: ou=people,o=suffix
    3: uid=kdz,ou=people,o=suffix
    4: cn=addresses,uid=kdz,ou=people,o=suffix
    5: uid=hyc,ou=people,o=suffix

Then:

     dn.base="ou=people,o=suffix" match 2;

     dn.one="ou=people,o=suffix" match 3, and 5;

     dn.subtree="ou=people,o=suffix" match 2, 3, 4, and 5; and

     dn.children="ou=people,o=suffix" match 3, 4, and 5.

Entries may also be selected using a filter:

    to filter=<ldap filter>

where <ldap filter> is a string representation of an LDAP search
filter, as described in RFC4515.  For example:

    to filter=(objectClass=person)

Note that entries may be selected by both DN and filter by including
both qualifiers in the <what> clause.

    to dn.one="ou=people,o=suffix" filter=(objectClass=person)

Attributes within an entry are selected by including a comma-separated
list of attribute names in the <what> selector:

    attrs=<attribute list>

A specific value of an attribute is selected by using a single
attribute name and also using a value selector:

    attrs=<attribute> val[.<style>]=<regex>

There are two special pseudo attributes entry and children.  To read
(and hence return) a target entry, the subject must have read access
to the target's entry attribute.  To perform a search, the subject
must have search access to the search base's entry attribute. To add
or delete an entry, the subject must have write access to the entry's
entry attribute AND must have write access to the entry's parent's
children attribute.  To rename an entry, the subject must have write
access to entry's entry attribute AND have write access to both the
old parent's and new parent's children attributes.  The complete
examples at the end of this section should help clear things up.

Lastly, there is a special entry selector "*" that is used to select
any entry.  It is used when no other <what> selector has been
provided.  It's equivalent to "dn=.*"

8.3.2. Who to grant access to
-----------------------------

The <who> part identifies the entity or entities being granted access.
Note that access is granted to "entities" not "entries." The following
table summarizes entity specifiers:

Table 5.3: Access Entity Specifiers

Specifier                          Entities
.................................. .................................. 
*                                  All, including anonymous and
                                   authenticated users
anonymous                          Anonymous (non-authenticated)
                                   users
users                              Authenticated users
self                               User associated with target entry
dn[.<basic-style>]=<regex>         Users matching a regular
                                   expression
dn.<scope-style>=<DN>              Users within scope of a DN

The DN specifier behaves much like <what> clause DN specifiers.

Other control factors are also supported.  For example, a <who> can be
restricted by an entry listed in a DN-valued attribute in the entry to
which the access applies:

    dnattr=<dn-valued attribute name>

The dnattr specification is used to give access to an entry whose DN
is listed in an attribute of the entry (e.g., give access to a group
entry to whoever is listed as the owner of the group entry).

Some factors may not be appropriate in all environments (or any). For
example, the domain factor relies on IP to domain name lookups. As
these can easily be spoofed, the domain factor should be avoided.

8.3.3. The access to grant
--------------------------

The kind of <access> granted can be one of the following:

Table 5.4: Access Levels

Level                               Privileges Description
...................... ....................... ...................... 
none                                        =0 no access
disclose                                    =d needed for information
                                               disclosure on error
auth                                       =dx needed to authenticate
                                               (bind)
compare                                   =cdx needed to compare
search                                   =scdx needed to apply search
                                               filters
read                                    =rscdx needed to read search
                                               results
write                                  =wrscdx needed to
                                               modify/rename
manage                                =mwrscdx needed to manage

Each level implies all lower levels of access. So, for example,
granting someone write access to an entry also grants them read,
search, compare, auth and disclose access.  However, one may use the
privileges specifier to grant specific permissions.

8.3.4. Access Control Evaluation
--------------------------------

When evaluating whether some requester should be given access to an
entry and/or attribute, slapd compares the entry and/or attribute to
the <what> selectors given in the configuration.  For each entry,
access controls provided in the database which holds the entry (or the
global access directives if not held in any database) apply first,
followed by the global access directives (which are held in the
frontend database definition). However, when dealing with an access
list, because the global access list is effectively appended to each
per-database list, if the resulting list is non-empty then the access
list will end with an implicit access to * by * none directive. If
there are no access directives applicable to a backend, then a default
read is used.

Within this priority, access directives are examined in the order in
which they appear in the configuration attribute.  Slapd stops with
the first <what> selector that matches the entry and/or attribute. The
corresponding access directive is the one slapd will use to evaluate
access.

Next, slapd compares the entity requesting access to the <who>
selectors within the access directive selected above in the order in
which they appear. It stops with the first <who> selector that matches
the requester. This determines the access the entity requesting access
has to the entry and/or attribute.

Finally, slapd compares the access granted in the selected <access>
clause to the access requested by the client. If it allows greater or
equal access, access is granted. Otherwise, access is denied.

The order of evaluation of access directives makes their placement in
the configuration file important. If one access directive is more
specific than another in terms of the entries it selects, it should
appear first in the configuration. Similarly, if one <who> selector is
more specific than another it should come first in the access
directive. The access control examples given below should help make
this clear.

8.3.5. Access Control Examples
------------------------------

The access control facility described above is quite powerful.  This
section shows some examples of its use for descriptive purposes.

A simple example:

    olcAccess: to * by * read

This access directive grants read access to everyone.

    olcAccess: to *
        by self write
        by anonymous auth
        by * read

This directive allows the user to modify their entry, allows anonymous
to authenticate against these entries, and allows all others to read
these entries.  Note that only the first by <who> clause which matches
applies.  Hence, the anonymous users are granted auth, not read.  The
last clause could just as well have been "by users read".

It is often desirable to restrict operations based upon the level of
protection in place.  The following shows how security strength
factors (SSF) can be used.

    olcAccess: to *
        by ssf=128 self write
        by ssf=64 anonymous auth
        by ssf=64 users read

This directive allows users to modify their own entries if security
protections of strength 128 or better have been established, allows
authentication access to anonymous users, and read access when
strength 64 or better security protections have been established.  If
the client has not establish sufficient security protections, the
implicit by * none clause would be applied.

The following example shows the use of style specifiers to select the
entries by DN in two access directives where ordering is significant.

    olcAccess: to dn.children="dc=example,dc=com"
         by * search
    olcAccess: to dn.children="dc=com"
         by * read

Read access is granted to entries under the dc=com subtree, except for
those entries under the dc=example,dc=com subtree, to which search
access is granted.  No access is granted to dc=com as neither access
directive matches this DN.  If the order of these access directives
was reversed, the trailing directive would never be reached, since all
entries under dc=example,dc=com are also under dc=com entries.

Also note that if no olcAccess: to directive matches or no by <who>
clause, access is denied.  When dealing with an access list, because
the global access list is effectively appended to each per-database
list, if the resulting list is non-empty then the access list will end
with an implicit access to * by * none directive. If there are no
access directives applicable to a backend, then a default read is
used.

The next example again shows the importance of ordering, both of the
access directives and the by <who> clauses.  It also shows the use of
an attribute selector to grant access to a specific attribute and
various <who> selectors.

    olcAccess: to dn.subtree="dc=example,dc=com" attrs=homePhone
        by self write
        by dn.children=dc=example,dc=com" search
        by peername.regex=IP=10\..+ read
    olcAccess: to dn.subtree="dc=example,dc=com"
        by self write
        by dn.children="dc=example,dc=com" search
        by anonymous auth

This example applies to entries in the "dc=example,dc=com" subtree. To
all attributes except homePhone, an entry can write to itself, entries
under example.com entries can search by them, anybody else has no
access (implicit by * none) excepting for authentication/authorization
(which is always done anonymously).  The homePhone attribute is
writable by the entry, searchable by entries under example.com,
readable by clients connecting from network 10, and otherwise not
readable (implicit by * none).  All other access is denied by the
implicit access to * by * none.

Sometimes it is useful to permit a particular DN to add or remove
itself from an attribute. For example, if you would like to create a
group and allow people to add and remove only their own DN from the
member attribute, you could accomplish it with an access directive
like this:

    olcAccess: to attrs=member,entry
         by dnattr=member selfwrite

The dnattr <who> selector says that the access applies to entries
listed in the member attribute. The selfwrite access selector says
that such members can only add or delete their own DN from the
attribute, not other values. The addition of the entry attribute is
required because access to the entry is required to access any of the
entry's attributes.

8.3.6. Access Control Ordering
------------------------------

Since the ordering of olcAccess directives is essential to their
proper evaluation, but LDAP attributes normally do not preserve the
ordering of their values, OpenLDAP uses a custom schema extension to
maintain a fixed ordering of these values. This ordering is maintained
by prepending a "{X}" numeric index to each value, similarly to the
approach used for ordering the configuration entries. These index tags
are maintained automatically by slapd and do not need to be specified
when originally defining the values. For example, when you create the
settings

    olcAccess: to attrs=member,entry
         by dnattr=member selfwrite
    olcAccess: to dn.children="dc=example,dc=com"
         by * search
    olcAccess: to dn.children="dc=com"
         by * read

when you read them back using slapcat or ldapsearch they will contain

    olcAccess: {0}to attrs=member,entry
         by dnattr=member selfwrite
    olcAccess: {1}to dn.children="dc=example,dc=com"
         by * search
    olcAccess: {2}to dn.children="dc=com"
         by * read

The numeric index may be used to specify a particular value to change
when using ldapmodify to edit the access rules. This index can be used
instead of (or in addition to) the actual access value. Using this
numeric index is very helpful when multiple access rules are being
managed.

For example, if we needed to change the second rule above to grant
write access instead of search, we could try this LDIF:

    changetype: modify
    delete: olcAccess
    olcAccess: to dn.children="dc=example,dc=com" by * search
    -
    add: olcAccess
    olcAccess: to dn.children="dc=example,dc=com" by * write
    -

But this example will not guarantee that the existing values remain in
their original order, so it will most likely yield a broken security
configuration. Instead, the numeric index should be used:

    changetype: modify
    delete: olcAccess
    olcAccess: {1}
    -
    add: olcAccess
    olcAccess: {1}to dn.children="dc=example,dc=com" by * write
    -

This example deletes whatever rule is in value #1 of the olcAccess
attribute (regardless of its value) and adds a new value that is
explicitly inserted as value #1. The result will be

    olcAccess: {0}to attrs=member,entry
         by dnattr=member selfwrite
    olcAccess: {1}to dn.children="dc=example,dc=com"
         by * write
    olcAccess: {2}to dn.children="dc=com"
         by * read

which is exactly what was intended.

8.4. Access Control Common Examples
-----------------------------------

8.4.1. Basic ACLs
-----------------

Generally one should start with some basic ACLs such as:

    access to attrs=userPassword
        by self =xw
        by anonymous auth
        by * none


      access to *
        by self write
        by users read
        by * none

The first ACL allows users to update (but not read) their passwords,
anonymous users to authenticate against this attribute, and
(implicitly) denying all access to others.

The second ACL allows users full access to their entry, authenticated
users read access to anything, and (implicitly) denying all access to
others (in this case, anonymous users).

8.4.2. Matching Anonymous and Authenticated users
-------------------------------------------------

An anonymous user has a empty DN. While the dn.exact="" or
dn.regex="^$" could be used, slapd(8)) offers an anonymous shorthand
which should be used instead.

    access to *
      by anonymous none
      by * read

denies all access to anonymous users while granting others read.

Authenticated users have a subject DN. While dn.regex=".+" will match
any authenticated user, OpenLDAP provides the users short hand which
should be used instead.

    access to *
      by users read
      by * none

This ACL grants read permissions to authenticated users while denying
others (i.e.: anonymous users).

8.4.3. Controlling rootdn access
--------------------------------

You could specify the rootdn in slapd.conf(5) or slapd.d without
specifying a rootpw. Then you have to add an actual directory entry
with the same dn, e.g.:

    dn: cn=Manager,o=MyOrganization
    cn: Manager
    sn: Manager
    objectClass: person
    objectClass: top
    userPassword: {SSHA}someSSHAdata

Then binding as the rootdn will require a regular bind to that DN,
which in turn requires auth access to that entry's DN and
userPassword, and this can be restricted via ACLs. E.g.:

    access to dn.base="cn=Manager,o=MyOrganization"
      by peername.regex=127\.0\.0\.1 auth
      by peername.regex=192\.168\.0\..* auth
      by users none
      by * none

The ACLs above will only allow binding using rootdn from localhost and
192.168.0.0/24.

8.4.4. Controlling the LDAP Proxied Authorization Control
---------------------------------------------------------

The Proxied Authorization Control allows a client to request that an
operation be processed under a provided authorization identity instead
of under the current authentication identity associated with the
connection.

This facility is controlled by the authz-policy configuration option
and by the authzTo and authzFrom attributes. It can be further
controlled by applying access control to those attributes.

A client application might bind as cn=Client,o=MyOrganization whose
entry looks like this:

    dn: cn=Client,o=MyOrganization
    cn: Client
    objectClass: organizationalRole
    objectClass: simpleSecurityObject
    objectClass: top
    userPassword: {SSHA}someSSHAdata
    authzTo: dn.regex:^cn=[^,]+,ou=People,o=MyOrganization$

To make use of the proxy facility, the client needs at least auth
privilege on the authzTo attribute:

    access to dn.exact=cn=Client,o=MyOrganization attr=authzTo
      by self auth
      by * break

This access would be automatically granted if
cn=Client,o=MyOrganization has read privilege on its own entry.

Now if you want to lock down the use of this powerful account, you
might write an ACL like this:

    access to dn.exact=cn=Client,o=MyOrganization attr=authzTo
      by self peername.regex=192\.168\.0\..*  ssf=256 auth
      by * none

Now, cn=Client,o=MyOrganization can only make use of the proxy
authorization control if it has connected from an appropriate IP
address using a sufficient level of cryptographic protection. No other
IDs can even see the authzTo attribute.

8.4.5. Managing access with Groups
----------------------------------

There are a few ways to do this. One approach is illustrated here.
Consider the following DIT layout:

    +-dc=example,dc=com
    +---cn=administrators,dc=example,dc=com
    +---cn=fred blogs,dc=example,dc=com

and the following group object (in LDIF format):

    dn: cn=administrators,dc=example,dc=com
    cn: administrators of this region
    objectclass: groupOfNames  (important for the group acl feature)
    member: cn=fred blogs,dc=example,dc=com
    member: cn=somebody else,dc=example,dc=com

One can then grant access to the members of this this group by adding
appropriate by group clause to an access directive in slapd.conf(5).
For instance,

    access to dn.children="dc=example,dc=com"
        by self write
        by group.exact="cn=Administrators,dc=example,dc=com" write
        by * auth

Like by dn clauses, one can also use expand to expand the group name
based upon the regular expression matching of the target, that is, the
to dn.regex). For instance,

    access to dn.regex="(.+,)?ou=People,(dc=[^,]+,dc=[^,]+)$"
             attrs=children,entry,uid
        by group.expand="cn=Managers,$2" write
        by users read
        by * auth

The above illustration assumed that the group members are to be found
in the member attribute type of the groupOfNames object class. If you
need to use a different group object and/or a different attribute type
then use the following slapd.conf(5) (abbreviated) syntax:

    access to <what>
            by group/<objectclass>/<attributename>=<DN> <access>

For example:

    access to *
      by group/organizationalRole/roleOccupant="cn=Administrator,dc=example,dc=com" write

In this case, we have an ObjectClass organizationalRole which contains
the administrator DN's in the roleOccupant attribute. For instance:

    dn: cn=Administrator,dc=example,dc=com
    cn: Administrator
    objectclass: organizationalRole
    roleOccupant: cn=Jane Doe,dc=example,dc=com

Note: the specified member attribute type MUST be of DN or
NameAndOptionalUID syntax, and the specified object class SHOULD allow
the attribute type.

Dynamic Groups are also supported in Access Control. Please see
slapo-dynlist(5) and the Dynamic Lists overlay section.

8.4.6. Granting access to a subset of attributes
------------------------------------------------

You can grant access to a set of attributes by specifying a list of
attribute names in the ACL to clause. To be useful, you also need to
grant access to the entry itself. Also note how children controls the
ability to add, delete, and rename entries.

    # mail: self may write, authenticated users may read
    access to attrs=mail
      by self write
      by users read
      by * none

    # cn, sn: self my write, all may read
    access to attrs=cn,sn
      by self write
      by * read

    # immediate children: only self can add/delete entries under this entry
    access to attrs=children
      by self write

    # entry itself: self may write, all may read
    access to attrs=entry
      by self write
      by * read

    # other attributes: self may write, others have no access
    access to *
      by self write
      by * none

ObjectClass names may also be specified in this list, which will
affect all the attributes that are required and/or allowed by that
objectClass. Actually, names in attrlist that are prefixed by @ are
directly treated as objectClass names. A name prefixed by ! is also
treated as an objectClass, but in this case the access rule affects
the attributes that are not required nor allowed by that objectClass.

8.4.7. Allowing a user write to all entries below theirs
--------------------------------------------------------

For a setup where a user can write to its own record and to all of its
children:

    access to dn.regex="(.+,)?(uid=[^,]+,o=Company)$"
       by dn.exact,expand="$2" write
       by anonymous auth

(Add more examples for above)

8.4.8. Allowing entry creation
------------------------------

Let's say, you have it like this:

        o=<basedn>
            ou=domains
                associatedDomain=<somedomain>
                    ou=users
                        uid=<someuserid>
                        uid=<someotheruserid>
                    ou=addressbooks
                        uid=<someuserid>
                            cn=<someone>
                            cn=<someoneelse>

and, for another domain <someotherdomain>:

        o=<basedn>
            ou=domains
                associatedDomain=<someotherdomain>
                    ou=users
                        uid=<someuserid>
                        uid=<someotheruserid>
                    ou=addressbooks
                        uid=<someotheruserid>
                            cn=<someone>
                            cn=<someoneelse>

then, if you wanted user uid=<someuserid> to ONLY create an entry for
its own thing, you could write an ACL like this:

    # this rule lets users of "associatedDomain=<matcheddomain>"
    # write under "ou=addressbook,associatedDomain=<matcheddomain>,ou=domains,o=<basedn>",
    # i.e. a user can write ANY entry below its domain's address book;
    # this permission is necessary, but not sufficient, the next
    # will restrict this permission further


    access to dn.regex="^ou=addressbook,associatedDomain=([^,]+),ou=domains,o=<basedn>$" attrs=children
            by dn.regex="^uid=([^,]+),ou=users,associatedDomain=$1,ou=domains,o=<basedn>$$" write
            by * none


    # Note that above the "by" clause needs a "regex" style to make sure
    # it expands to a DN that starts with a "uid=<someuserid>" pattern
    # while substituting the associatedDomain submatch from the "what" clause.


    # This rule lets a user with "uid=<matcheduid>" of "<associatedDomain=matcheddomain>"
    # write (i.e. add, modify, delete) the entry whose DN is exactly
    # "uid=<matcheduid>,ou=addressbook,associatedDomain=<matcheddomain>,ou=domains,o=<basedn>"
    # and ANY entry as subtree of it


    access to dn.regex="^(.+,)?uid=([^,]+),ou=addressbook,associatedDomain=([^,]+),ou=domains,o=<basedn>$"
            by dn.exact,expand="uid=$2,ou=users,associatedDomain=$3,ou=domains,o=<basedn>" write
            by * none


    # Note that above the "by" clause uses the "exact" style with the "expand"
    # modifier because now the whole pattern can be rebuilt by means of the
    # submatches from the "what" clause, so a "regex" compilation and evaluation
    # is no longer required.

8.4.9. Tips for using regular expressions in Access Control
-----------------------------------------------------------

Always use dn.regex=<pattern> when you intend to use regular
expression matching. dn=<pattern> alone defaults to dn.exact<pattern>.

Use (.+) instead of (.*) when you want at least one char to be
matched. (.*) matches the empty string as well.

Don't use regular expressions for matches that can be done otherwise
in a safer and cheaper manner. Examples:

    dn.regex=".*dc=example,dc=com"

is unsafe and expensive:

o    unsafe because any string containing dc=example,dc=com will
     match, not only those that end with the desired pattern; use
     .*dc=example,dc=com$ instead.

o    unsafe also because it would allow any attributeType ending with
     dc as naming attribute for the first RDN in the string, e.g. a
     custom attributeType mydc would match as well. If you really need
     a regular expression that allows just dc=example,dc=com or any of
     its subtrees, use ^(.+,)?dc=example,dc=com$, which means:
     anything to the left of dc=..., if any (the question mark after
     the pattern within brackets), must end with a comma;

o    expensive because if you don't need submatches, you could use
     scoping styles, e.g.

    dn.subtree="dc=example,dc=com"

to include dc=example,dc=com in the matching patterns,

    dn.children="dc=example,dc=com"

to exclude dc=example,dc=com from the matching patterns, or

    dn.onelevel="dc=example,dc=com"

to allow exactly one sublevel matches only.

Always use ^ and $ in regexes, whenever appropriate, because
ou=(.+),ou=(.+),ou=addressbooks,o=basedn will match
something=bla,ou=xxx,ou=yyy,ou=addressbooks,o=basedn,ou=addressbooks,o=basedn,dc=some,dc=org

Always use ([^,]+) to indicate exactly one RDN, because (.+) can
include any number of RDNs; e.g. ou=(.+),dc=example,dc=com will match
ou=My,o=Org,dc=example,dc=com, which might not be what you want.

Never add the rootdn to the by clauses. ACLs are not even processed
for operations performed with rootdn identity (otherwise there would
be no reason to define a rootdn at all).

Use shorthands. The user directive matches authenticated users and the
anonymous directive matches anonymous users.

Don't use the dn.regex form for <by> clauses if all you need is
scoping and/or substring replacement; use scoping styles (e.g. exact,
onelevel, children or subtree) and the style modifier expand to cause
substring expansion.

For instance,

    access to dn.regex=".+,dc=([^,]+),dc=([^,]+)$"
      by dn.regex="^[^,],ou=Admin,dc=$1,dc=$2$$" write

although correct, can be safely and efficiently replaced by

    access to dn.regex=".+,(dc=[^,]+,dc=[^,]+)$"
      by dn.onelevel,expand="ou=Admin,$1" write

where the regex in the <what> clause is more compact, and the one in
the <by> clause is replaced by a much more efficient scoping style of
onelevel with substring expansion.

8.4.10. Granting and Denying access based on security strength factors (ssf)
----------------------------------------------------------------------------

You can restrict access based on the security strength factor (SSF)

    access to dn="cn=example,cn=edu"
          by * ssf=256 read

0 (zero) implies no protection, 1 implies integrity protection only,
56 DES or other weak ciphers, 112 triple DES and similar ciphers, 128
RC4, Blowfish and other similar ciphers, 256 modern ciphers.

Other possibilities:

    transport_ssf=<n>
    tls_ssf=<n>
    sasl_ssf=<n>

256 is recommended.

See slapd.conf(5) for information on ssf.

8.4.11. When things aren't working as expected
----------------------------------------------

Consider this example:

    access to *
      by anonymous auth

    access to *
      by self write

    access to *
      by users read

You may think this will allow any user to login, to read everything
and change his own data if he is logged in. But in this example only
the login works and an ldapsearch returns no data. The Problem is that
SLAPD goes through its access config line by line and stops as soon as
it finds a match in the part of the access rule.(here: to *)

To get what we wanted the file has to read:

    access to *
      by anonymous auth
      by self write
      by users read

The general rule is: "special access rules first, generic access rules
last"

See also slapd.access(5), loglevel 128 and slapacl(8) for debugging
information.

8.5. Sets - Granting rights based on relationships
--------------------------------------------------

Sets are best illustrated via examples. The following sections will
present a few set ACL examples in order to facilitate their
understanding.

(Sets in Access Controls FAQ Entry:
http://www.openldap.org/faq/data/cache/1133.html)

Note: Sets are considered experimental.

8.5.1. Groups of Groups
-----------------------

The OpenLDAP ACL for groups doesn't expand groups within groups, which
are groups that have another group as a member. For example:

 dn: cn=sudoadm,ou=group,dc=example,dc=com
 cn: sudoadm
 objectClass: groupOfNames
 member: uid=john,ou=people,dc=example,dc=com
 member: cn=accountadm,ou=group,dc=example,dc=com

 dn: cn=accountadm,ou=group,dc=example,dc=com
 cn: accountadm
 objectClass: groupOfNames
 member: uid=mary,ou=people,dc=example,dc=com

If we use standard group ACLs with the above entries and allow members
of the sudoadm group to write somewhere, mary won't be included:

 access to dn.subtree="ou=sudoers,dc=example,dc=com"
         by group.exact="cn=sudoadm,ou=group,dc=example,dc=com" write
         by * read

With sets we can make the ACL be recursive and consider group within
groups. So for each member that is a group, it is further expanded:

 access to dn.subtree="ou=sudoers,dc=example,dc=com"
       by set="[cn=sudoadm,ou=group,dc=example,dc=com]/member* & user" write
       by * read

This set ACL means: take the cn=sudoadm DN, check its member
attribute(s) (where the "*" means recursively) and intersect the
result with the authenticated user's DN. If the result is non-empty,
the ACL is considered a match and write access is granted.

The following drawing explains how this set is built:

** Unable to import figure set-recursivegroup.png **

Figure X.Y: Populating a recursive group set

First we get the uid=john DN. This entry doesn't have a member
attribute, so the expansion stops here.  Now we get to cn=accountadm.
This one does have a member attribute, which is uid=mary. The uid=mary
entry, however, doesn't have member, so we stop here again. The end
comparison is:

 {"uid=john,ou=people,dc=example,dc=com","uid=mary,ou=people,dc=example,dc=com"} & user

If the authenticated user's DN is any one of those two, write access
is granted. So this set will include mary in the sudoadm group and she
will be allowed the write access.

8.5.2. Group ACLs without DN syntax
-----------------------------------

The traditional group ACLs, and even the previous example about
recursive groups, require that the members are specified as DNs
instead of just usernames.

With sets, however, it's also possible to use simple names in group
ACLs, as this example will show.

Let's say we want to allow members of the sudoadm group to write to
the ou=sudoers branch of our tree. But our group definition now is
using memberUid for the group members:

 dn: cn=sudoadm,ou=group,dc=example,dc=com
 cn: sudoadm
 objectClass: posixGroup
 gidNumber: 1000
 memberUid: john

With this type of group, we can't use group ACLs. But with a set ACL
we can grant the desired access:

 access to dn.subtree="ou=sudoers,dc=example,dc=com"
       by set="[cn=sudoadm,ou=group,dc=example,dc=com]/memberUid & user/uid" write
       by * read

We use a simple intersection where we compare the uid attribute of the
connecting (and authenticated) user with the memberUid attributes of
the group. If they match, the intersection is non-empty and the ACL
will grant write access.

This drawing illustrates this set when the connecting user is
authenticated as uid=john,ou=people,dc=example,dc=com:

** Unable to import figure set-memberUid.png **

Figure X.Y: Sets with memberUid

In this case, it's a match. If it were mary authenticating, however,
she would be denied write access to ou=sudoers because her uid
attribute is not listed in the group's memberUid.

8.5.3. Following references
---------------------------

We will now show a quite powerful example of what can be done with
sets. This example tends to make OpenLDAP administrators smile after
they have understood it and its implications.

Let's start with an user entry:

 dn: uid=john,ou=people,dc=example,dc=com
 uid: john
 objectClass: inetOrgPerson
 givenName: John
 sn: Smith
 cn: john
 manager: uid=mary,ou=people,dc=example,dc=com

Writing an ACL to allow the manager to update some attributes is quite
simple using sets:

 access to dn.exact="uid=john,ou=people,dc=example,dc=com"
    attrs=carLicense,homePhone,mobile,pager,telephoneNumber
    by self write
    by set="this/manager & user" write
    by * read

In that set, this expands to the entry being accessed, so that
this/manager expands to uid=mary,ou=people,dc=example,dc=com when
john's entry is accessed.  If the manager herself is accessing John's
entry, the ACL will match and write access to those attributes will be
granted.

So far, this same behavior can be obtained with the dnattr keyword.
With sets, however, we can further enhance this ACL. Let's say we want
to allow the secretary of the manager to also update these attributes.
This is how we do it:

 access to dn.exact="uid=john,ou=people,dc=example,dc=com"
    attrs=carLicense,homePhone,mobile,pager,telephoneNumber
    by self write
    by set="this/manager & user" write
    by set="this/manager/secretary & user" write
    by * read

Now we need a picture to help explain what is happening here (entries
shortened for clarity):

** Unable to import figure set-following-references.png **

Figure X.Y: Sets jumping through entries

In this example, Jane is the secretary of Mary, which is the manager
of John. This whole relationship is defined with the manager and
secretary attributes, which are both of the distinguishedName syntax
(i.e., full DNs). So, when the uid=john entry is being accessed, the
this/manager/secretary set becomes
{"uid=jane,ou=people,dc=example,dc=com"} (follow the references in the
picture):

 this = [uid=john,ou=people,dc=example,dc=com]
 this/manager = \
   [uid=john,ou=people,dc=example,dc=com]/manager = uid=mary,ou=people,dc=example,dc=com
 this/manager/secretary = \
   [uid=mary,ou=people,dc=example,dc=com]/secretary = uid=jane,ou=people,dc=example,dc=com

The end result is that when Jane accesses John's entry, she will be
granted write access to the specified attributes. Better yet, this
will happen to any entry she accesses which has Mary as the manager.

This is all cool and nice, but perhaps gives too much power to
secretaries. Maybe we need to further restrict it. For example, let's
only allow executive secretaries to have this power:

 access to dn.exact="uid=john,ou=people,dc=example,dc=com"
   attrs=carLicense,homePhone,mobile,pager,telephoneNumber
   by self write
   by set="this/manager & user" write
   by set="this/manager/secretary &
           [cn=executive,ou=group,dc=example,dc=com]/member* &
           user" write
   by * read

It's almost the same ACL as before, but we now also require that the
connecting user be a member of the (possibly nested) cn=executive
group.


9. Limits
=========

9.1. Introduction
-----------------

It is usually desirable to limit the server resources that can be
consumed by each LDAP client. OpenLDAP provides two sets of limits: a
size limit, which can restrict the number of entries that a client can
retrieve in a single operation, and a time limit which restricts the
length of time that an operation may continue. Both types of limit can
be given different values depending on who initiated the operation.

9.2. Soft and Hard limits
-------------------------

The server administrator can specify both soft limits and hard limits.
Soft limits can be thought of as being the default limit value. Hard
limits cannot be exceeded by ordinary LDAP users.

LDAP clients can specify their own size and time limits when issuing
search operations. This feature has been present since the earliest
version of X.500.

If the client specifies a limit then the lower of the requested value
and the hard limit will become the limit for the operation.

If the client does not specify a limit then the server applies the
soft limit.

Soft and Hard limits are often referred to together as administrative
limits. Thus, if an LDAP client requests a search that would return
more results than the limits allow it will get an adminLimitExceeded
error. Note that the server will usually return some results even if
the limit has been exceeded: this feature is useful to clients that
just want to check for the existence of some entries without needing
to see them all.

The rootdn is not subject to any limits.

9.3. Global Limits
------------------

Limits specified in the global part of the server configuration act as
defaults which are used if no database has more specific limits set.

In a slapd.conf(5) configuration the keywords are sizelimit and
timelimit. When using the slapd config backend, the corresponding
attributes are olcSizeLimit and olcTimeLimit. The syntax of these
values are the same in both cases.

The simple form sets both soft and hard limits to the same value:

   sizelimit {<integer>|unlimited}
   timelimit {<integer>|unlimited}

The default sizelimit is 500 entries and the default timelimit is 3600
seconds.

An extended form allows soft and hard limits to be set separately:

   sizelimit size[.{soft|hard}]=<integer> [...]
   timelimit time[.{soft|hard}]=<integer> [...]

Thus, to set a soft sizelimit of 10 entries and a hard limit of 75
entries:

  sizelimit size.soft=10 size.hard=75

9.3.1. Special Size Limits
--------------------------

There are other forms of size limits in addition to the soft and hard
limits. Note that when using the simple sizelimit form, none of these
special limits are changed.

9.3.1.1. Unchecked Limits
-------------------------

The unchecked keyword sets a limit on how many entries the server will
examine after doing index lookups but before evaluating filter
matches. If the set of candidates exceeds this limit, the search is
aborted. The purpose is to avoid causing excessive workload on slapd
if a filter uses attributes that are not properly indexed, and can be
critical for very large directories.

   sizelimit size.unchecked={<integer>|unlimited|disabled}

The default is unlimited. The disabled setting prevents a search from
being performed at all. This may be useful in the per-database limits
described below, to disallow searches for a specific set of users.

9.3.1.2. Paged Results Limits
-----------------------------

If the LDAP client adds the pagedResultsControl to the search
operation, the hard size limit is used by default, because the request
for a specific page size is considered an explicit request for a
limitation on the number of entries to be returned. However, the size
limit applies to the total count of entries returned within the
search, and not to a single page.

Additional size limits may be enforced for paged searches.

The size.pr limit controls the maximum page size:

   sizelimit size.pr={<integer>|noEstimate|unlimited}

<integer> is the maximum page size if no explicit size is set.
noEstimate has no effect in the current implementation as the server
does not return an estimate of the result size anyway. unlimited
indicates that no limit is applied to the maximum page size.

The size.prtotal limit controls the total number of entries that can
be returned by a paged search. By default the limit is the same as the
normal size.hard limit.

   size.prtotal={<integer>|unlimited|disabled}

unlimited removes the limit on the number of entries that can be
returned by a paged search. disabled can be used to selectively
disable paged result searches.

9.4. Per-Database Limits
------------------------

Each database can have its own set of limits that override the global
ones. The syntax is more flexible, and it allows different limits to
be applied to different entities. Note that an entity is different
from an entry: the term entity is used here to indicate the ID of the
person or process that has initiated the LDAP operation.

In a slapd.conf(5) configuration the keyword is limits. When using the
slapd config backend, the corresponding attribute is olcLimits. The
syntax of the values is the same in both cases.

   limits <selector> <limit> [<limit> [...]]

The limits clause can be specified multiple times to apply different
limits to different initiators. The server examines each clause in
turn until it finds one that matches the operation's initiator or base
DN. If no match is found, the global limits will be used.

9.4.1. Specify who the limits apply to
--------------------------------------

The <selector> part of the limits clause can take any of these values:

Table 9.1: Limits Entity Specifiers

Specifier                          Entities
.................................. .................................. 
*                                  All, including anonymous and
                                   authenticated users
anonymous                          Anonymous (non-authenticated)
                                   users
users                              Authenticated users
dn[.<type>][.<style>]=<pattern>]   Entry or entries within a scope
                                   that match <pattern>
group[/oc[/at]]=<pattern>          Members of a group

Where

type can be one of self or this and

style can be one of exact, base, onelevel, subtree, children, regex,
or anonymous

More information can be found in the slapd.conf(5) or slapd-config(5)
manual pages.

9.4.2. Specify time limits
--------------------------

The syntax for time limits is

   time[.{soft|hard}]=<integer>

where integer is the number of seconds slapd will spend answering a
search request.

If neither soft nor hard is specified, the value is used for both,
e.g.:

   limits anonymous time=27

The value unlimited may be used to remove the hard time limit
entirely, e.g.:

   limits dn.exact="cn=anyuser,dc=example,dc=org" time.hard=unlimited

9.4.3. Specifying size limits
-----------------------------

The syntax for size limit is

   size[.{soft|hard}]=<integer>

where <integer> is the maximum number of entries slapd will return
when answering a search request.

In addition to soft and hard limits, other limits are also available,
with the same meanings described for the global limits configuration
above.

9.5. Example Limit Configurations
---------------------------------

9.5.1. Simple Global Limits
---------------------------

This simple global configuration fragment applies size and time limits
to all searches by all users except rootdn. It limits searches to 50
results and sets an overall time limit of 10 seconds.

   sizelimit 50
   timelimit 10

9.5.2. Global Hard and Soft Limits
----------------------------------

It is sometimes useful to limit the size of result sets but to allow
clients to request a higher limit where needed. This can be achieved
by setting separate hard and soft limits.

   sizelimit size.soft=5 size.hard=100

To prevent clients from doing very inefficient non-indexed searches,
add the unchecked limit:

   sizelimit size.soft=5 size.hard=100 size.unchecked=100

9.5.3. Giving specific users larger limits
------------------------------------------

Having set appropriate default limits in the global configuration, you
may want to give certain users the ability to retrieve larger result
sets. Here is a way to do that in the per-database configuration:

   limits dn.exact="cn=anyuser,dc=example,dc=org" size=100000
   limits dn.exact="cn=personnel,dc=example,dc=org" size=100000
   limits dn.exact="cn=dirsync,dc=example,dc=org" size=100000

It is generally best to avoid mentioning specific users in the server
configuration. A better way is to give the higher limits to a group:

   limits group/groupOfNames/member="cn=bigwigs,dc=example,dc=org" size=100000

9.5.4. Limiting who can do paged searches
-----------------------------------------

It may be required that certain applications need very large result
sets that they retrieve using paged searches, but that you do not want
ordinary LDAP users to use the pagedResults control. The pr and
prtotal limits can help:

   limits group/groupOfNames/member="cn=dirsync,dc=example,dc=org" size.prtotal=unlimited
   limits users size.soft=5 size.hard=100 size.prtotal=disabled
   limits anonymous size.soft=2 size.hard=5 size.prtotal=disabled

9.6. Glued/Subordinate database configurations
----------------------------------------------

When using subordinate databases, it is necessary for any limits that
are to be applied across the parent and its subordinates to be defined
in both the parent and its subordinates. Otherwise the settings on the
subordinate databases are not honored.

9.7. Further Information
------------------------

For further information please see slapd.conf(5), ldapsearch(1) and
slapd.access(5)


10. Database Creation and Maintenance Tools
===========================================

This section tells you how to create a slapd database from scratch,
and how to do trouble shooting if you run into problems. There are two
ways to create a database. First, you can create the database on-line
using LDAP. With this method, you simply start up slapd and add
entries using the LDAP client of your choice. This method is fine for
relatively small databases (a few hundred or thousand entries,
depending on your requirements). This method works for database types
which support updates.

The second method of database creation is to do it off-line using
special utilities provided with slapd(8). This method is best if you
have many thousands of entries to create, which would take an
unacceptably long time using the LDAP method, or if you want to ensure
the database is not accessed while it is being created. Note that not
all database types support these utilities.

10.1. Creating a database over LDAP
-----------------------------------

With this method, you use the LDAP client of your choice (e.g., the
ldapadd(1)) to add entries, just like you would once the database is
created.  You should be sure to set the following options in the
configuration file before starting slapd(8).

        suffix <dn>

As described in the General Database Directives section, this option
defines which entries are to be held by this database. You should set
this to the DN of the root of the subtree you are trying to create. 
For example:

        suffix "dc=example,dc=com"

You should be sure to specify a directory where the index files should
be created:

        directory <directory>

For example:

        directory /usr/local/var/openldap-data

You need to create this directory with appropriate permissions such
that slapd can write to it.

You need to configure slapd so that you can connect to it as a
directory user with permission to add entries. You can configure the
directory to support a special super-user or root user just for this
purpose. This is done through the following two options in the
database definition:

        rootdn <dn>
        rootpw <passwd>

For example:

        rootdn "cn=Manager,dc=example,dc=com"
        rootpw secret

These options specify a DN and password that can be used to
authenticate as the super-user entry of the database (i.e., the entry
allowed to do anything). The DN and password specified here will
always work, regardless of whether the entry named actually exists or
has the password given. This solves the chicken-and-egg problem of how
to authenticate and add entries before any entries yet exist.

Finally, you should make sure that the database definition contains
the index definitions you want:

        index {<attrlist> | default} [pres,eq,approx,sub,none]

For example, to index the cn, sn, uid and objectclass attributes, the
following index directives could be used:

        index cn,sn,uid pres,eq,approx,sub
        index objectClass eq

This would create presence, equality, approximate, and substring
indices for the cn, sn, and uid attributes and an equality index for
the objectClass attribute.  Note that not all index types are
available with all attribute types.  See The slapd Configuration File
section for more information on this option.

Once you have configured things to your liking, start up slapd,
connect with your LDAP client, and start adding entries.  For example,
to add an organization entry and an organizational role entry using
the ldapadd tool, you could create an LDIF file called entries.ldif
with the contents:

        # Organization for Example Corporation
        dn: dc=example,dc=com
        objectClass: dcObject
        objectClass: organization
        dc: example
        o: Example Corporation
        description: The Example Corporation

        # Organizational Role for Directory Manager
        dn: cn=Manager,dc=example,dc=com
        objectClass: organizationalRole
        cn: Manager
        description: Directory Manager

and then use a command like this to actually create the entry:

        ldapadd -f entries.ldif -x -D "cn=Manager,dc=example,dc=com" -w secret

The above command assumes settings provided in the above examples.

10.2. Creating a database off-line
----------------------------------

The second method of database creation is to do it off-line, using the
slapd database tools described below. This method is best if you have
many thousands of entries to create, which would take an unacceptably
long time to add using the LDAP method described above. These tools
read the slapd configuration file and an input file containing a text
representation of the entries to add. For database types which support
the tools, they produce the database files directly (otherwise you
must use the on-line method above). Also, the input file must be
completely valid, as these tools do fewer consistency checks than the
on-line method.

Note: this Guide is not meant to provide exhaustive documentation on
the software. The tool descriptions here only list a few of the
available options for each command. Read the associated manpages for
complete documentation on all of the available options.

There are several important configuration options you will want to be
sure and set in the config file database definition first:

        suffix <dn>

As described in the General Database Directives section, this option
defines which entries are to be held by this database. You should set
this to the DN of the root of the subtree you are trying to create. 
For example:

        suffix "dc=example,dc=com"

You should be sure to specify a directory where the index files should
be created:

        directory <directory>

For example:

        directory /usr/local/var/openldap-data

Finally, you need to specify which indices you want to build.  This is
done by one or more index options.

        index {<attrlist> | default} [pres,eq,approx,sub,none]

For example:

        index cn,sn,uid pres,eq,approx,sub
        index objectClass eq

This would create presence, equality, approximate, and substring
indices for the cn, sn, and uid attributes and an equality index for
the objectClass attribute.  Note that not all index types are
available with all attribute types.  See The slapd Configuration File
section for more information on this option.

10.2.1. The slapadd program
---------------------------

Once you've configured things to your liking, you create the primary
database and associated indices by running the slapadd(8) program:

        slapadd -l <inputfile> -f <slapdconfigfile>
                [-d <debuglevel>] [-n <integer>|-b <suffix>]

The arguments have the following meanings:

        -l <inputfile>

Specifies the LDIF input file containing the entries to add in text
form (described below in the The LDIF text entry format section).

        -f <slapdconfigfile>

Specifies the slapd configuration file that tells where to create the
indices, what indices to create, etc.

        -F <slapdconfdirectory>

Specifies a config directory.  If both -f and -F are specified, the
config file will be read and converted to config  directory format and
written to the specified directory.  If neither option is specified,
an attempt to read the default config directory will be made before
trying to use the default config file. If a valid config directory
exists then the default config file is ignored. If dryrun mode is also
specified, no conversion will occur.

        -d <debuglevel>

Turn on debugging, as specified by <debuglevel>. The debug levels are
the same as for slapd.  See the Command-Line Options section in
Running slapd.

        -n <databasenumber>

An optional argument that specifies which database to modify.  The
first database listed in the configuration file is 1, the second 2,
etc. By default, the first database in the configuration file is used.
Should not be used in conjunction with -b.

        -b <suffix>

An optional argument that specifies which database to modify.  The
provided suffix is matched against a database suffix directive to
determine the database number. Should not be used in conjunction with
-n.

10.2.2. The slapindex program
-----------------------------

Sometimes it may be necessary to regenerate indices (such as after
modifying slapd.conf(5)). This is possible using the slapindex(8)
program.  slapindex is invoked like this

        slapindex -f <slapdconfigfile>
                [-d <debuglevel>] [-n <databasenumber>|-b <suffix>] [attr...]

Where the -f, -d, -n and -b options are the same as for the slapadd(1)
program.  If no specific attributes are listed, slapindex rebuilds all
indices based upon the current database contents.

10.2.3. The slapcat program
---------------------------

The slapcat program is used to dump the database to an LDIF file. 
This can be useful when you want to make a human-readable backup of
your database or when you want to edit your database off-line.  The
program is invoked like this:

        slapcat -l <filename> -f <slapdconfigfile>
                [-d <debuglevel>] [-n <databasenumber>|-b <suffix>]

where -n or -b is used to select the database in the slapd.conf(5)
specified using -f.  The corresponding LDIF output is written to
standard output or to the file specified using the -l option.

10.3. The LDIF text entry format
--------------------------------

The LDAP Data Interchange Format (LDIF) is used to represent LDAP
entries in a simple text format.  This section provides a brief
description of the LDIF entry format which complements ldif(5) and the
technical specification RFC2849.

The basic form of an entry is:

        # comment
        dn: <distinguished name>
        <attrdesc>: <attrvalue>
        <attrdesc>: <attrvalue>

        ...

Lines starting with a '#' character are comments.  An attribute
description may be a simple attribute type like cn or objectClass or
1.2.3 (an OID associated with an attribute type) or may include
options such as cn;lang_en_US or userCertificate;binary.

A line may be continued by starting the next line with a single space
or tab character.  For example:

        dn: cn=Barbara J Jensen,dc=example,dc=
         com
        cn: Barbara J
          Jensen

is equivalent to:

        dn: cn=Barbara J Jensen,dc=example,dc=com
        cn: Barbara J Jensen

Multiple attribute values are specified on separate lines. e.g.,

        cn: Barbara J Jensen
        cn: Babs Jensen

If an <attrvalue> contains non-printing characters or begins with a
space, a colon (':'), or a less than ('<'), the <attrdesc> is followed
by a double colon and the base64 encoding of the value.  For example,
the value " begins with a space" would be encoded like this:

        cn:: IGJlZ2lucyB3aXRoIGEgc3BhY2U=

You can also specify a URL containing the attribute value. For
example, the following specifies the jpegPhoto value should be
obtained from the file /path/to/file.jpeg.

        jpegPhoto:< file:///path/to/file.jpeg

Multiple entries within the same LDIF file are separated by blank
lines. Here's an example of an LDIF file containing three entries.

        # Barbara's Entry
        dn: cn=Barbara J Jensen,dc=example,dc=com
        cn: Barbara J Jensen
        cn: Babs Jensen
        objectClass: person
        sn: Jensen

        # Bjorn's Entry
        dn: cn=Bjorn J Jensen,dc=example,dc=com
        cn: Bjorn J Jensen
        cn: Bjorn Jensen
        objectClass: person
        sn: Jensen
        # Base64 encoded JPEG photo
        jpegPhoto:: /9j/4AAQSkZJRgABAAAAAQABAAD/2wBDABALD
         A4MChAODQ4SERATGCgaGBYWGDEjJR0oOjM9PDkzODdASFxOQ
         ERXRTc4UG1RV19iZ2hnPk1xeXBkeFxlZ2P/2wBDARESEhgVG

        # Jennifer's Entry
        dn: cn=Jennifer J Jensen,dc=example,dc=com
        cn: Jennifer J Jensen
        cn: Jennifer Jensen
        objectClass: person
        sn: Jensen
        # JPEG photo from file
        jpegPhoto:< file:///path/to/file.jpeg

Notice that the jpegPhoto in Bjorn's entry is base 64 encoded and the
jpegPhoto in Jennifer's entry is obtained from the location indicated
by the URL.

Note: Trailing spaces are not trimmed from values in an LDIF file. Nor
are multiple internal spaces compressed. If you don't want them in
your data, don't put them there.


11. Backends
============

Backends do the actual work of storing or retrieving data in response
to LDAP requests. Backends may be compiled statically into slapd, or
when module support is enabled, they may be dynamically loaded.

If your installation uses dynamic modules, you may need to add the
relevant moduleload directives to the examples that follow. The name
of the module for a backend is usually of the form:

        back_<backend name>.la

So for example, if you need to load the mdb backend, you would
configure

        moduleload back_mdb.la

11.1. LDAP
----------

11.1.1. Overview
----------------

The LDAP backend to slapd(8) is not an actual database; instead it
acts as a proxy to forward incoming requests to another LDAP server.
While processing requests it will also chase referrals, so that
referrals are fully processed instead of being returned to the slapd
client.

Sessions that explicitly Bind to the back-ldap database always create
their own private connection to the remote LDAP server. Anonymous
sessions will share a single anonymous connection to the remote
server. For sessions bound through other mechanisms, all sessions with
the same DN will share the same connection. This connection pooling
strategy can enhance the proxy's efficiency by reducing the overhead
of repeatedly making/breaking multiple connections.

The ldap database can also act as an information service, i.e. the
identity of locally authenticated clients is asserted to the remote
server, possibly in some modified form. For this purpose, the proxy
binds to the remote server with some administrative identity, and, if
required, authorizes the asserted identity.

It is heavily used by a lot of other Backends and Overlays.

11.1.2. back-ldap Configuration
-------------------------------

As previously mentioned, slapd-ldap(5) is used behind the scenes by
many other Backends and Overlays. Some of them merely provide a few
configuration directive themselves, but have available to the
administrator the whole of the slapd-ldap(5) options.

For example, the Translucent Proxy, which retrieves entries from a
remote LDAP server that can be partially overridden by the defined
database, has only four specific translucent- directives, but can be
configured using any of the normal slapd-ldap(5) options. See
slapo-translucent(5) for details.

Other Overlays allow you to tag directives in front of a normal
slapd-ldap(5) directive. For example, the slapo-chain(5) overlay does
this:

"There are very few chain overlay specific directives; however,
directives related to the instances of the ldap backend that may be
implicitly instantiated by the overlay may assume a special meaning
when used in conjunction with this overlay.  They are described in
slapd-ldap(5), and they also need to be prefixed by chain-."

You may have also seen the slapd-ldap(5) backend used and described in
the Push Based Replication section of the guide.

It should therefore be obvious that the slapd-ldap(5) backend is
extremely flexible and heavily used throughout the OpenLDAP Suite.

The following is a very simple example, but already the power of the
slapd-ldap(5) backend is seen by use of a uri list:

        database        ldap
        suffix          "dc=suretecsystems,dc=com"
        rootdn          "cn=slapd-ldap"
        uri             ldap://localhost/ ldap://remotehost ldap://remotehost2

The URI list is space or comma-separated. Whenever the server that
responds is not the first one in the list, the list is rearranged and
the responsive server is moved to the head, so that it will be first
contacted the next time a connection needs be created.

This feature can be used to provide a form of load balancing when
using Mirror mode replication.

11.1.3. Further Information
---------------------------

slapd-ldap(5)

11.2. LDIF
----------

11.2.1. Overview
----------------

The LDIF backend to slapd(8) is a basic storage backend that stores
entries in text files in LDIF format, and exploits the filesystem to
create the tree structure of the database. It is intended as a cheap,
low performance easy to use backend.

When using the cn=config dynamic configuration database with
persistent storage, the configuration data is stored using this
backend. See slapd-config(5) for more information

11.2.2. back-ldif Configuration
-------------------------------

Like many other backends, the LDIF backend can be instantiated with
very few configuration lines:

        include ./schema/core.schema

        database  ldif
        directory ./ldif
        suffix    "dc=suretecsystems,dc=com"
        rootdn    "cn=LDIF,dc=suretecsystems,dc=com"
        rootpw    LDIF

If we add the dcObject for dc=suretecsystems,dc=com, you can see how
this is added behind the scenes on the file system:

   dn: dc=suretecsystems,dc=com
   objectClass: dcObject
   objectClass: organization
   dc: suretecsystems
   o: Suretec Systems Ltd

Now we add it to the directory:

   ldapadd -x -H ldap://localhost:9011 -f suretec.ldif -D "cn=LDIF,dc=suretecsystems,dc=com" -w LDIF
   adding new entry "dc=suretecsystems,dc=com"

And inside ./ldif we have:

   ls ./ldif
   dc=suretecsystems,dc=com.ldif

which again contains:

   cat ldif/dc\=suretecsystems\,dc\=com.ldif

   dn: dc=suretecsystems
   objectClass: dcObject
   objectClass: organization
   dc: suretecsystems
   o: Suretec Systems Ltd.
   structuralObjectClass: organization
   entryUUID: 2134b714-e3a1-102c-9a15-f96ee263886d
   creatorsName: cn=LDIF,dc=suretecsystems,dc=com
   createTimestamp: 20080711142643Z
   entryCSN: 20080711142643.661124Z#000000#000#000000
   modifiersName: cn=LDIF,dc=suretecsystems,dc=com
   modifyTimestamp: 20080711142643Z

This is the complete format you would get when exporting your
directory using slapcat etc.

11.2.3. Further Information
---------------------------

slapd-ldif(5)

11.3. LMDB
----------

11.3.1. Overview
----------------

The mdb backend to slapd(8) is the recommended primary backend for a
normal slapd database.  It uses OpenLDAP's own Lightning Memory-Mapped
Database (LMDB) library to store data and replaces the BerkeleyDB
backends used in older OpenLDAP releases.

It supports indexing, it uses no caching, and requires no tuning to
deliver maximum search performance.  It is fully hierarchical and
supports subtree renames in constant time.

11.3.2. back-mdb Configuration
------------------------------

The mdb backend can be instantiated with very few configuration lines:

        include ./schema/core.schema

        database  mdb
        directory ./mdb
        suffix    "dc=suretecsystems,dc=com"
        rootdn    "cn=mdb,dc=suretecsystems,dc=com"
        rootpw    mdb
        maxsize   1073741824

In addition to the usual parameters that a minimal configuration
requires, the mdb backend requires a maximum size to be set. This
should be the largest that the database is ever anticipated to grow
(in bytes). The filesystem must also provide enough free space to
accommodate this size.

11.3.3. Further Information
---------------------------

slapd-mdb(5)

11.4. Metadirectory
-------------------

11.4.1. Overview
----------------

The meta backend to slapd(8) performs basic LDAP proxying with respect
to a set of remote LDAP servers, called "targets". The information
contained in these servers can be presented as belonging to a single
Directory Information Tree (DIT).

A basic knowledge of the functionality of the slapd-ldap(5) backend is
recommended. This backend has been designed as an enhancement of the
ldap backend. The two backends share many features (actually they also
share portions of code). While the ldap backend is intended to proxy
operations directed to a single server, the meta backend is mainly
intended for proxying of multiple servers and possibly naming context 
masquerading.

These features, although useful in many scenarios, may result in
excessive overhead for some applications, so its use should be
carefully considered.

11.4.2. back-meta Configuration
-------------------------------

LATER

11.4.3. Further Information
---------------------------

slapd-meta(5)

11.5. Monitor
-------------

11.5.1. Overview
----------------

The monitor backend to slapd(8) is not an actual database; if enabled,
it is automatically generated and dynamically maintained by slapd with
information about the running status of the daemon.

To inspect all monitor information, issue a subtree search with base
cn=Monitor, requesting that attributes "+" and "*" are returned. The
monitor backend produces mostly operational attributes, and LDAP only
returns operational attributes that are explicitly requested. 
Requesting attribute "+" is an extension which requests all
operational attributes.

See the Monitoring section.

11.5.2. back-monitor Configuration
----------------------------------

The monitor database can be instantiated only once, i.e. only one
occurrence of "database monitor" can occur in the slapd.conf(5) file. 
Also the suffix is automatically set to "cn=Monitor".

You can however set a rootdn and rootpw. The following is all that is
needed to instantiate a monitor backend:

        include ./schema/core.schema

        database monitor
        rootdn "cn=monitoring,cn=Monitor"
        rootpw monitoring

You can also apply Access Control to this database like any other
database, for example:

        access to dn.subtree="cn=Monitor"
             by dn.exact="uid=Admin,dc=my,dc=org" write
             by users read
             by * none

Note: The core.schema must be loaded for the monitor database to work.

A small example of the data returned via ldapsearch would be:

        ldapsearch -x -H ldap://localhost:9011 -b 'cn=Monitor'
        # extended LDIF
        #
        # LDAPv3
        # base <cn=Monitor> with scope subtree
        # filter: (objectclass=*)
        # requesting: ALL
        #

        # Monitor
        dn: cn=Monitor
        objectClass: monitorServer
        cn: Monitor
        description: This subtree contains monitoring/managing objects.
        description: This object contains information about this server.
        description: Most of the information is held in operational attributes, which
         must be explicitly requested.

        # Backends, Monitor
        dn: cn=Backends,cn=Monitor
        objectClass: monitorContainer
        cn: Backends
        description: This subsystem contains information about available backends.

Please see the Monitoring section for complete examples of information
available via this backend.

11.5.3. Further Information
---------------------------

slapd-monitor(5)

11.6. Null
----------

11.6.1. Overview
----------------

The Null backend to slapd(8) is surely the most useful part of slapd:

o    Searches return success but no entries.

o    Compares return compareFalse.

o    Updates return success (unless readonly is on) but do nothing.

o    Binds other than as the rootdn fail unless the database option
     "bind on" is given.

o    The slapadd(8) and slapcat(8) tools are equally exciting.

Inspired by the /dev/null device.

11.6.2. back-null Configuration
-------------------------------

This has to be one of the shortest configurations you'll ever do. In
order to test this, your slapd.conf file would look like:

        database null
        suffix "cn=Nothing"
        bind on

bind on means:

"Allow binds as any DN in this backend's suffix, with any password.
The default is "off"."

To test this backend with ldapsearch:

        ldapsearch -x -H ldap://localhost:9011 -D "uid=none,cn=Nothing" -w testing -b 'cn=Nothing'
        # extended LDIF
        #
        # LDAPv3
        # base <cn=Nothing> with scope subtree
        # filter: (objectclass=*)
        # requesting: ALL
        #

        # search result
        search: 2
        result: 0 Success

        # numResponses: 1

11.6.3. Further Information
---------------------------

slapd-null(5)

11.7. Passwd
------------

11.7.1. Overview
----------------

The PASSWD backend to slapd(8) serves up the user account information
listed in the system passwd(5) file (defaulting to /etc/passwd).

This backend is provided for demonstration purposes only. The DN of
each entry is "uid=<username>,<suffix>".

11.7.2. back-passwd Configuration
---------------------------------

The configuration using slapd.conf a slightly longer, but not much.
For example:

        include ./schema/core.schema

        database passwd
        suffix "cn=passwd"

Again, testing this with ldapsearch would result in something like:

        ldapsearch -x -H ldap://localhost:9011 -b 'cn=passwd'
        # extended LDIF
        #
        # LDAPv3
        # base <cn=passwd> with scope subtree
        # filter: (objectclass=*)
        # requesting: ALL
        #

        # passwd
        dn: cn=passwd
        cn: passwd
        objectClass: organizationalUnit

        # root, passwd
        dn: uid=root,cn=passwd
        objectClass: person
        objectClass: uidObject
        uid: root
        cn: root
        sn: root
        description: root

11.7.3. Further Information
---------------------------

slapd-passwd(5)

11.8. Perl
----------

11.8.1. Overview
----------------

The Perl backend to slapd(8) works by embedding a perl(1) interpreter
into slapd(8). Any perl database section of the configuration file
slapd.conf(5) must then specify what Perl module to use. Slapd then
creates a new Perl object that handles all the requests for that
particular instance of the backend.

11.8.2. back-perl Configuration
-------------------------------

LATER

11.8.3. Further Information
---------------------------

slapd-perl(5)

11.9. Relay
-----------

11.9.1. Overview
----------------

The primary purpose of this slapd(8) backend is to map a naming
context defined in a database running in the same slapd(8) instance
into a virtual naming context, with attributeType and objectClass
manipulation, if required. It requires the rwm overlay.

This backend and the above mentioned overlay are experimental.

11.9.2. back-relay Configuration
--------------------------------

LATER

11.9.3. Further Information
---------------------------

slapd-relay(5)

11.10. SQL
----------

11.10.1. Overview
-----------------

The primary purpose of this slapd(8) backend is to PRESENT information
stored in some RDBMS as an LDAP subtree without any programming (some
SQL and maybe stored procedures can't be considered programming,
anyway ;).

That is, for example, when you (some ISP) have account information you
use in an RDBMS, and want to use modern solutions that expect such
information in LDAP (to authenticate users, make email lookups etc.).
Or you want to synchronize or distribute information between different
sites/applications that use RDBMSes and/or LDAP. Or whatever else...

It is NOT designed as a general-purpose backend that uses RDBMS
instead of LMDB (as the standard back-mdb backend does), though it can
be used as such with several limitations. Please see LDAP vs RDBMS for
discussion.

The idea is to use some meta-information to translate LDAP queries to
SQL queries, leaving relational schema untouched, so that old
applications can continue using it without any modifications. This
allows SQL and LDAP applications to interoperate without replication,
and exchange data as needed.

The SQL backend is designed to be tunable to virtually any relational
schema without having to change source (through that meta-information
mentioned). Also, it uses ODBC to connect to RDBMSes, and is highly
configurable for SQL dialects RDBMSes may use, so it may be used for
integration and distribution of data on different RDBMSes, OSes, hosts
etc., in other words, in highly heterogeneous environments.

This backend is experimental and deprecated.

11.10.2. back-sql Configuration
-------------------------------

This backend has to be one of the most abused and complex backends
there is. Therefore, we will go through a simple, small example that
comes with the OpenLDAP source and can be found in
servers/slapd/back-sql/rdbms_depend/README

For this example we will be using PostgreSQL.

First, we add to /etc/odbc.ini a block of the form:

        [example]                        <===
        Description         = Example for OpenLDAP's back-sql
        Driver              = PostgreSQL
        Trace               = No
        Database            = example    <===
        Servername          = localhost
        UserName            = manager    <===
        Password            = secret     <===
        Port                = 5432
        ;Protocol            = 6.4
        ReadOnly            = No
        RowVersioning       = No
        ShowSystemTables    = No
        ShowOidColumn       = No
        FakeOidIndex        = No
        ConnSettings        =

The relevant information for our test setup is highlighted with '<==='
on the right above.

Next, we add to /etc/odbcinst.ini a block of the form:

        [PostgreSQL]
        Description     = ODBC for PostgreSQL
        Driver          = /usr/lib/libodbcpsql.so
        Setup           = /usr/lib/libodbcpsqlS.so
        FileUsage       = 1

We will presume you know how to create a database and user in
PostgreSQL and how to set a password. Also, we'll presume you can
populate the 'example' database you've just created with the following
files, as found in servers/slapd/back-sql/rdbms_depend/pgsql

        backsql_create.sql, testdb_create.sql, testdb_data.sql, testdb_metadata.sql

Lastly, run the test:

        [root@localhost]# cd $SOURCES/tests
        [root@localhost]# SLAPD_USE_SQL=pgsql ./run sql-test000

Briefly, you should see something like (cut short for space):

        Cleaning up test run directory leftover from previous run.
        Running ./scripts/sql-test000-read...
        running defines.sh
        Starting slapd on TCP/IP port 9011...
        Testing SQL backend read operations...
        Waiting 5 seconds for slapd to start...
        Testing correct bind... dn:cn=Mitya Kovalev,dc=example,dc=com
        Testing incorrect bind (should fail)... ldap_bind: Invalid credentials (49)

        ......

        Filtering original ldif...
        Comparing filter output...
        >>>>> Test succeeded

The test is basically readonly; this can be performed by all RDBMSes
(listed above).

There is another test, sql-test900-write, which is currently enabled
only for PostgreSQL and IBM db2.

Using sql-test000, files in servers/slapd/back-sql/rdbms_depend/pgsql/
and the man page, you should be set.

Note: This backend is experimental and deprecated.

11.10.3. Further Information
----------------------------

slapd-sql(5) and servers/slapd/back-sql/rdbms_depend/README


12. Overlays
============

Overlays are software components that provide hooks to functions
analogous to those provided by backends, which can be stacked on top
of the backend calls and as callbacks on top of backend responses to
alter their behavior.

Overlays may be compiled statically into slapd, or when module support
is enabled, they may be dynamically loaded. Most of the overlays are
only allowed to be configured on individual databases.

Some can be stacked on the frontend as well, for global use. This
means that they can be executed after a request is parsed and
validated, but right before the appropriate database is selected. The
main purpose is to affect operations regardless of the database they
will be handled by, and, in some cases, to influence the selection of
the database by massaging the request DN.

Essentially, overlays represent a means to:

o    customize the behavior of existing backends without changing the
     backend code and without requiring one to write a new custom
     backend with complete functionality

o    write functionality of general usefulness that can be applied to
     different backend types

When using slapd.conf(5), overlays that are configured before any
other databases are considered global, as mentioned above. In fact
they are implicitly stacked on top of the frontend database. They can
also be explicitly configured as such:

        database frontend
        overlay <overlay name>

Overlays are usually documented by separate specific man pages in
section 5; the naming convention is

        slapo-<overlay name>

All distributed core overlays have a man page. Feel free to contribute
to any, if you think there is anything missing in describing the
behavior of the component and the implications of all the related
configuration directives.

Official overlays are located in

        servers/slapd/overlays/

That directory also contains the file slapover.txt, which describes
the rationale of the overlay implementation, and may serve as a
guideline for the development of custom overlays.

Contribware overlays are located in

        contrib/slapd-modules/<overlay name>/

along with other types of run-time loadable components; they are
officially distributed, but not maintained by the project.

All the current overlays in OpenLDAP are listed and described in
detail in the following sections.

12.1. Access Logging
--------------------

12.1.1. Overview
----------------

This overlay can record accesses to a given backend database on
another database.

This allows all of the activity on a given database to be reviewed
using arbitrary LDAP queries, instead of just logging to local flat
text files. Configuration options are available for selecting a subset
of operation types to log, and to automatically prune older log
records from the logging database. Log records are stored with audit
schema to assure their readability whether viewed as LDIF or in raw
form.

It is also used for delta-syncrepl replication

Note: An accesslog database is unique to a given provider. It should
never be replicated.

12.1.2. Access Logging Configuration
------------------------------------

The following is a basic example that implements Access Logging:

        database mdb
        suffix dc=example,dc=com
        ...
        overlay accesslog
        logdb cn=log
        logops writes reads
        logold (objectclass=person)

        database mdb
        suffix cn=log
        ...
        index reqStart eq
        access to *
          by dn.base="cn=admin,dc=example,dc=com" read

The following is an example used for delta-syncrepl replication:

        database mdb
        suffix cn=accesslog
        directory /usr/local/var/openldap-accesslog
        rootdn cn=accesslog
        index default eq
        index entryCSN,objectClass,reqEnd,reqResult,reqStart,reqDN

Accesslog overlay definitions for the primary db

        database mdb
        suffix dc=example,dc=com
        ...
        overlay accesslog
        logdb cn=accesslog
        logops writes
        logsuccess TRUE
        # scan the accesslog DB every day, and purge entries older than 7 days
        logpurge 07+00:00 01+00:00

An example search result against cn=accesslog might look like:

        [ghenry@suretec ghenry]# ldapsearch -x -b cn=accesslog
        # extended LDIF
        #
        # LDAPv3
        # base <cn=accesslog> with scope subtree
        # filter: (objectclass=*)
        # requesting: ALL
        #

        # accesslog
        dn: cn=accesslog
        objectClass: auditContainer
        cn: accesslog

        # 20080110163829.000004Z, accesslog
        dn: reqStart=20080110163829.000004Z,cn=accesslog
        objectClass: auditModify
        reqStart: 20080110163829.000004Z
        reqEnd: 20080110163829.000005Z
        reqType: modify
        reqSession: 196696
        reqAuthzID: cn=admin,dc=suretecsystems,dc=com
        reqDN: uid=suretec-46022f8$,ou=Users,dc=suretecsystems,dc=com
        reqResult: 0
        reqMod: sambaPwdCanChange:- ###CENSORED###
        reqMod: sambaPwdCanChange:+ ###CENSORED###
        reqMod: sambaNTPassword:- ###CENSORED###
        reqMod: sambaNTPassword:+ ###CENSORED###
        reqMod: sambaPwdLastSet:- ###CENSORED###
        reqMod: sambaPwdLastSet:+ ###CENSORED###
        reqMod: entryCSN:= 20080110163829.095157Z#000000#000#000000
        reqMod: modifiersName:= cn=admin,dc=suretecsystems,dc=com
        reqMod: modifyTimestamp:= 20080110163829Z

        # search result
        search: 2
        result: 0 Success

        # numResponses: 3
        # numEntries: 2

12.1.3. Further Information
---------------------------

slapo-accesslog(5) and the delta-syncrepl replication section.

12.2. Audit Logging
-------------------

The Audit Logging overlay can be used to record all changes on a given
backend database to a specified log file.

12.2.1. Overview
----------------

If the need arises whereby changes need to be logged as standard LDIF,
then the auditlog overlay slapo-auditlog (5) can be used. Full
examples are available in the man page slapo-auditlog (5)

12.2.2. Audit Logging Configuration
-----------------------------------

If the directory is running vi slapd.d, then the following LDIF could
be used to add the overlay to the overlay list in cn=config and set
what file the LDIF gets logged to (adjust to suit)

       dn: olcOverlay=auditlog,olcDatabase={1}mdb,cn=config
       changetype: add
       objectClass: olcOverlayConfig
       objectClass: olcAuditLogConfig
       olcOverlay: auditlog
       olcAuditlogFile: /tmp/auditlog.ldif

In this example for testing, we are logging changes to
/tmp/auditlog.ldif

A typical LDIF file created by slapo-auditlog(5) would look like:

       # add 1196797576 dc=suretecsystems,dc=com cn=admin,dc=suretecsystems,dc=com
       dn: dc=suretecsystems,dc=com
       changetype: add
       objectClass: dcObject
       objectClass: organization
       dc: suretecsystems
       o: Suretec Systems Ltd.
       structuralObjectClass: organization
       entryUUID: 1606f8f8-f06e-1029-8289-f0cc9d81e81a
       creatorsName: cn=admin,dc=suretecsystems,dc=com
       modifiersName: cn=admin,dc=suretecsystems,dc=com
       createTimestamp: 20051123130912Z
       modifyTimestamp: 20051123130912Z
       entryCSN: 20051123130912.000000Z#000001#000#000000
       auditContext: cn=accesslog
       # end add 1196797576

       # add 1196797577 dc=suretecsystems,dc=com cn=admin,dc=suretecsystems,dc=com
       dn: ou=Groups,dc=suretecsystems,dc=com
       changetype: add
       objectClass: top
       objectClass: organizationalUnit
       ou: Groups
       structuralObjectClass: organizationalUnit
       entryUUID: 160aaa2a-f06e-1029-828a-f0cc9d81e81a
       creatorsName: cn=admin,dc=suretecsystems,dc=com
       modifiersName: cn=admin,dc=suretecsystems,dc=com
       createTimestamp: 20051123130912Z
       modifyTimestamp: 20051123130912Z
       entryCSN: 20051123130912.000000Z#000002#000#000000
       # end add 1196797577

12.2.3. Further Information
---------------------------

slapo-auditlog(5)

12.3. Chaining
--------------

12.3.1. Overview
----------------

The chain overlay provides basic chaining capability to the underlying
database.

What is chaining? It indicates the capability of a DSA to follow
referrals on behalf of the client, so that distributed systems are
viewed as a single virtual DSA by clients that are otherwise unable to
"chase" (i.e. follow) referrals by themselves.

The chain overlay is built on top of the ldap backend; it is compiled
by default when --enable-ldap.

12.3.2. Chaining Configuration
------------------------------

In order to demonstrate how this overlay works, we shall discuss a
typical scenario which might be one provider server and three Syncrepl
replicas.

On each replica, add this near the top of the slapd.conf(5) file
(global), before any database definitions:

        overlay                    chain
        chain-uri                  "ldap://ldapprovider.example.com"
        chain-idassert-bind        bindmethod="simple"
                                   binddn="cn=Manager,dc=example,dc=com"
                                   credentials="<secret>"
                                   mode="self"
        chain-tls                  start
        chain-return-error         TRUE

Add this below your syncrepl statement:

        updateref                  "ldap://ldapprovider.example.com/"

The chain-tls statement enables TLS from the replica to the ldap
provider. The DITs are exactly the same between these machines,
therefore whatever user bound to the replica will also exist on the
provider. If that DN does not have update privileges on the provider,
nothing will happen.

You will need to restart the replica after these slapd.conf changes.
Then, if you are using loglevel stats (256), you can monitor an
ldapmodify on the replica and the provider. (If you're using cn=config
no restart is required.)

Now start an ldapmodify on the replica and watch the logs. You should
expect something like:

        Sep  6 09:27:25 replica1 slapd[29274]: conn=11 fd=31 ACCEPT from IP=143.199.102.216:45181 (IP=143.199.102.216:389)
        Sep  6 09:27:25 replica1 slapd[29274]: conn=11 op=0 STARTTLS
        Sep  6 09:27:25 replica1 slapd[29274]: conn=11 op=0 RESULT oid= err=0 text=
        Sep  6 09:27:25 replica1 slapd[29274]: conn=11 fd=31 TLS established tls_ssf=256 ssf=256
        Sep  6 09:27:28 replica1 slapd[29274]: conn=11 op=1 BIND dn="uid=user1,ou=people,dc=example,dc=com" method=128
        Sep  6 09:27:28 replica1 slapd[29274]: conn=11 op=1 BIND dn="uid=user1,ou=People,dc=example,dc=com" mech=SIMPLE ssf=0
        Sep  6 09:27:28 replica1 slapd[29274]: conn=11 op=1 RESULT tag=97 err=0 text=
        Sep  6 09:27:28 replica1 slapd[29274]: conn=11 op=2 MOD dn="uid=user1,ou=People,dc=example,dc=com"
        Sep  6 09:27:28 replica1 slapd[29274]: conn=11 op=2 MOD attr=mail
        Sep  6 09:27:28 replica1 slapd[29274]: conn=11 op=2 RESULT tag=103 err=0 text=
        Sep  6 09:27:28 replica1 slapd[29274]: conn=11 op=3 UNBIND
        Sep  6 09:27:28 replica1 slapd[29274]: conn=11 fd=31 closed
        Sep  6 09:27:28 replica1 slapd[29274]: syncrepl_entry: LDAP_RES_SEARCH_ENTRY(LDAP_SYNC_MODIFY)
        Sep  6 09:27:28 replica1 slapd[29274]: syncrepl_entry: be_search (0)
        Sep  6 09:27:28 replica1 slapd[29274]: syncrepl_entry: uid=user1,ou=People,dc=example,dc=com
        Sep  6 09:27:28 replica1 slapd[29274]: syncrepl_entry: be_modify (0)

And on the provider you will see this:

        Sep  6 09:23:57 ldapprovider slapd[2961]: conn=55902 op=3 PROXYAUTHZ dn="uid=user1,ou=people,dc=example,dc=com"
        Sep  6 09:23:57 ldapprovider slapd[2961]: conn=55902 op=3 MOD dn="uid=user1,ou=People,dc=example,dc=com"
        Sep  6 09:23:57 ldapprovider slapd[2961]: conn=55902 op=3 MOD attr=mail
        Sep  6 09:23:57 ldapprovider slapd[2961]: conn=55902 op=3 RESULT tag=103 err=0 text=

Note: You can clearly see the PROXYAUTHZ line on the provider,
indicating the proper identity assertion for the update on the
provider. Also note the replica immediately receiving the Syncrepl
update from the provider.

12.3.3. Handling Chaining Errors
--------------------------------

By default, if chaining fails, the original referral is returned to
the client under the assumption that the client might want to try and
follow the referral.

With the following directive however, if the chaining fails at the
provider side, the actual error is returned to the client.

        chain-return-error TRUE

12.3.4. Read-Back of Chained Modifications
------------------------------------------

Occasionally, applications want to read back the data that they just
wrote. If a modification requested to a shadow server was silently
chained to its provider, an immediate read could result in receiving
data not yet synchronized. In those cases, clients should use the
dontusecopy control to ensure they are directed to the authoritative
source for that piece of data.

This control usually causes a referral to the actual source of the
data to be returned.  However, when the slapo-chain(5) overlay is
used, it intercepts the referral being returned in response to the
dontusecopy control, and tries to fetch the requested data.

12.3.5. Further Information
---------------------------

slapo-chain(5)

12.4. Constraints
-----------------

12.4.1. Overview
----------------

This overlay enforces a regular expression constraint on all values of
specified attributes during an LDAP modify request that contains add
or modify commands. It is used to enforce a more rigorous syntax when
the underlying attribute syntax is too general.

12.4.2. Constraint Configuration
--------------------------------

Configuration via slapd.conf(5) would look like:

        overlay constraint
        constraint_attribute mail regex ^[[:alnum:]]+@mydomain.com$
        constraint_attribute title uri
        ldap:///dc=catalog,dc=example,dc=com?title?sub?(objectClass=titleCatalog)

A specification like the above would reject any mail attribute which
did not look like <alphanumeric string>@mydomain.com.

It would also reject any title attribute whose values were not listed
in the title attribute of any titleCatalog entries in the given scope.

An example for use with cn=config:

       dn: olcOverlay=constraint,olcDatabase={1}mdb,cn=config
       changetype: add
       objectClass: olcOverlayConfig
       objectClass: olcConstraintConfig
       olcOverlay: constraint
       olcConstraintAttribute: mail regex ^[[:alnum:]]+@mydomain.com$
       olcConstraintAttribute: title uri ldap:///dc=catalog,dc=example,dc=com?title?sub?(objectClass=titleCatalog)

12.4.3. Further Information
---------------------------

slapo-constraint(5)

12.5. Dynamic Directory Services
--------------------------------

12.5.1. Overview
----------------

The dds overlay to slapd(8) implements dynamic objects as per RFC2589.
The name dds stands for Dynamic Directory Services. It allows to
define dynamic objects, characterized by the dynamicObject
objectClass.

Dynamic objects have a limited lifetime, determined by a time-to-live
(TTL) that can be refreshed by means of a specific refresh extended
operation. This operation allows to set the Client Refresh Period
(CRP), namely the period between refreshes that is required to
preserve the dynamic object from expiration. The expiration time is
computed by adding the requested TTL to the current time. When dynamic
objects reach the end of their lifetime without being further
refreshed, they are automatically deleted. There is no guarantee of
immediate deletion, so clients should not count on it.

12.5.2. Dynamic Directory Service Configuration
-----------------------------------------------

A usage of dynamic objects might be to implement dynamic meetings; in
this case, all the participants to the meeting are allowed to refresh
the meeting object, but only the creator can delete it (otherwise it
will be deleted when the TTL expires).

If we add the overlay to an example database, specifying a Max TTL of
1 day, a min of 10 seconds, with a default TTL of 1 hour. We'll also
specify an interval of 120 (less than 60s might be too small) seconds
between expiration checks and a tolerance of 5 second (lifetime of a
dynamic object will be entryTtl + tolerance).

       overlay dds
       dds-max-ttl     1d
       dds-min-ttl     10s
       dds-default-ttl 1h
       dds-interval    120s
       dds-tolerance   5s

and add an index:

       entryExpireTimestamp

Creating a meeting is as simple as adding the following:

       dn: cn=OpenLDAP Documentation Meeting,ou=Meetings,dc=example,dc=com
       objectClass: groupOfNames
       objectClass: dynamicObject
       cn: OpenLDAP Documentation Meeting
       member: uid=ghenry,ou=People,dc=example,dc=com
       member: uid=hyc,ou=People,dc=example,dc=com

12.5.2.1. Dynamic Directory Service ACLs
----------------------------------------

Allow users to start a meeting and to join it; restrict refresh to the
member; restrict delete to the creator:

       access to attrs=userPassword
          by self write
          by * read

       access to dn.base="ou=Meetings,dc=example,dc=com"
                 attrs=children
            by users write

       access to dn.onelevel="ou=Meetings,dc=example,dc=com"
                 attrs=entry
            by dnattr=creatorsName write
            by * read

       access to dn.onelevel="ou=Meetings,dc=example,dc=com"
                 attrs=participant
            by dnattr=creatorsName write
            by users selfwrite
            by * read

       access to dn.onelevel="ou=Meetings,dc=example,dc=com"
                 attrs=entryTtl
            by dnattr=member manage
            by * read

In simple terms, the user who created the OpenLDAP Documentation
Meeting can add new attendees, refresh the meeting using (basically
complete control):

       ldapexop -x -H ldap://ldaphost "refresh" "cn=OpenLDAP Documentation Meeting,ou=Meetings,dc=example,dc=com" "120" -D "uid=ghenry,ou=People,dc=example,dc=com" -W

Any user can join the meeting, but not add another attendee, but they
can refresh the meeting. The ACLs above are quite straight forward to
understand.

12.5.3. Further Information
---------------------------

slapo-dds(5)

12.6. Dynamic Groups
--------------------

12.6.1. Overview
----------------

This overlay extends the Compare operation to detect members of a
dynamic group. This overlay is now deprecated as all of its functions
are available using the Dynamic Lists overlay.

12.6.2. Dynamic Group Configuration
-----------------------------------

12.7. Dynamic Lists
-------------------

12.7.1. Overview
----------------

This overlay allows expansion of dynamic groups and lists. Instead of
having the group members or list attributes hard coded, this overlay
allows us to define an LDAP search whose results will make up the
group or list.

12.7.2. Dynamic List Configuration
----------------------------------

This module can behave both as a dynamic list and dynamic group,
depending on the configuration. The syntax is as follows:

       overlay dynlist
       dynlist-attrset <group-oc> <URL-ad> [member-ad]

The parameters to the dynlist-attrset directive have the following
meaning:

o    <group-oc>: specifies which object class triggers the subsequent
     LDAP search. Whenever an entry with this object class is
     retrieved, the search is performed.

o    <URL-ad>: is the name of the attribute which holds the search
     URI. It has to be a subtype of labeledURI. The attributes and
     values present in the search result are added to the entry unless
     member-ad is used (see below).

o    member-ad: if present, changes the overlay behavior into a
     dynamic group. Instead of inserting the results of the search in
     the entry, the distinguished name of the results are added as
     values of this attribute.

Here is an example which will allow us to have an email alias which
automatically expands to all user's emails according to our LDAP
filter:

In slapd.conf(5):

       overlay dynlist
       dynlist-attrset nisMailAlias labeledURI

This means that whenever an entry which has the nisMailAlias object
class is retrieved, the search specified in the labeledURI attribute
is performed.

Let's say we have this entry in our directory:

       cn=all,ou=aliases,dc=example,dc=com
       cn: all
       objectClass: nisMailAlias
       labeledURI: ldap:///ou=People,dc=example,dc=com?mail?one?(objectClass=inetOrgPerson)

If this entry is retrieved, the search specified in labeledURI will be
performed and the results will be added to the entry just as if they
have always been there. In this case, the search filter selects all
entries directly under ou=People that have the inetOrgPerson object
class and retrieves the mail attribute, if it exists.

This is what gets added to the entry when we have two users under
ou=People that match the filter:

** Unable to import figure allmail-en.png **

Figure X.Y: Dynamic List for all emails

The configuration for a dynamic group is similar. Let's see an example
which would automatically populate an allusers group with all the user
accounts in the directory.

In slapd.conf(5):

       include /path/to/dyngroup.schema
       ...
       overlay dynlist
       dynlist-attrset groupOfURLs labeledURI member

Note: We must include the dyngroup.schema file that defines the
groupOfURLs objectClass used in this example.

Let's apply it to the following entry:

       cn=allusers,ou=group,dc=example,dc=com
       cn: all
       objectClass: groupOfURLs
       labeledURI: ldap:///ou=people,dc=example,dc=com??one?(objectClass=inetOrgPerson)

The behavior is similar to the dynamic list configuration we had
before: whenever an entry with the groupOfURLs object class is
retrieved, the search specified in the labeledURI attribute is
performed. But this time, only the distinguished names of the results
are added, and as values of the member attribute.

This is what we get:

** Unable to import figure allusersgroup-en.png **

Figure X.Y: Dynamic Group for all users

Note that a side effect of this scheme of dynamic groups is that the
members need to be specified as full DNs. So, if you are planning in
using this for posixGroups, be sure to use RFC2307bis and some
attribute which can hold distinguished names. The memberUid attribute
used in the posixGroup object class can hold only names, not DNs, and
is therefore not suitable for dynamic groups.

12.7.3. Further Information
---------------------------

slapo-dynlist(5)

12.8. Reverse Group Membership Maintenance
------------------------------------------

12.8.1. Overview
----------------

In some scenarios, it may be desirable for a client to be able to
determine which groups an entry is a member of, without performing an
additional search. Examples of this are applications using the DIT for
access control based on group authorization.

The memberof overlay updates an attribute (by default memberOf)
whenever changes occur to the membership attribute (by default member)
of entries of the objectclass (by default groupOfNames) configured to
trigger updates.

Thus, it provides maintenance of the list of groups an entry is a
member of, when usual maintenance of groups is done by modifying the
members on the group entry.

12.8.2. Member Of Configuration
-------------------------------

The typical use of this overlay requires just enabling the overlay for
a specific database. For example, with the following minimal
slapd.conf:

        include /usr/share/openldap/schema/core.schema
        include /usr/share/openldap/schema/cosine.schema

        authz-regexp "gidNumber=0\\\+uidNumber=0,cn=peercred,cn=external,cn=auth"
                "cn=Manager,dc=example,dc=com"
        database        mdb
        suffix          "dc=example,dc=com"
        rootdn          "cn=Manager,dc=example,dc=com"
        rootpw          secret
        directory       /var/lib/ldap2.5
        checkpoint 256 5
        index   objectClass   eq
        index   uid           eq,sub

        overlay memberof

adding the following ldif:

        cat memberof.ldif
        dn: dc=example,dc=com
        objectclass: domain
        dc: example

        dn: ou=Group,dc=example,dc=com
        objectclass: organizationalUnit
        ou: Group

        dn: ou=People,dc=example,dc=com
        objectclass: organizationalUnit
        ou: People

        dn: uid=test1,ou=People,dc=example,dc=com
        objectclass: account
        uid: test1

        dn: cn=testgroup,ou=Group,dc=example,dc=com
        objectclass: groupOfNames
        cn: testgroup
        member: uid=test1,ou=People,dc=example,dc=com

Results in the following output from a search on the test1 user:

 # ldapsearch -LL -Y EXTERNAL -H ldapi:/// "(uid=test1)" -b dc=example,dc=com memberOf
 SASL/EXTERNAL authentication started
 SASL username: gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth
 SASL SSF: 0
 version: 1

 dn: uid=test1,ou=People,dc=example,dc=com
 memberOf: cn=testgroup,ou=Group,dc=example,dc=com

Note that the memberOf attribute is an operational attribute, so it
must be requested explicitly.

12.8.3. Further Information
---------------------------

slapo-memberof(5)

12.9. The Proxy Cache Engine
----------------------------

LDAP servers typically hold one or more subtrees of a DIT. Replica (or
shadow) servers hold shadow copies of entries held by one or more
provider servers.  Changes are propagated from the provider server to
replica servers using LDAP Sync replication.  An LDAP cache is a
special type of replica which holds entries corresponding to search
filters instead of subtrees.

12.9.1. Overview
----------------

The proxy cache extension of slapd is designed to improve the
responsiveness of the ldap and meta backends. It handles a search
request (query) by first determining whether it is contained in any
cached search filter. Contained requests are answered from the proxy
cache's local database. Other requests are passed on to the underlying
ldap or meta backend and processed as usual.

E.g. (shoesize>=9) is contained in (shoesize>=8) and (sn=Richardson)
is contained in (sn=Richards*)

Correct matching rules and syntaxes are used while comparing
assertions for query containment. To simplify the query containment
problem, a list of cacheable "templates" (defined below) is specified
at configuration time. A query is cached or answered only if it
belongs to one of these templates. The entries corresponding to cached
queries are stored in the proxy cache local database while its
associated meta information (filter, scope, base, attributes) is
stored in main memory.

A template is a prototype for generating LDAP search requests.
Templates are described by a prototype search filter and a list of
attributes which are required in queries generated from the template.
The representation for prototype filter is similar to RFC4515, except
that the assertion values are missing. Examples of prototype filters
are: (sn=),(&(sn=)(givenname=)) which are instantiated by search
filters (sn=Doe) and (&(sn=Doe)(givenname=John)) respectively.

The cache replacement policy removes the least recently used (LRU)
query and entries belonging to only that query. Queries are allowed a
maximum time to live (TTL) in the cache thus providing weak
consistency. A background task periodically checks the cache for
expired queries and removes them.

The Proxy Cache paper
(http://www.openldap.org/pub/kapurva/proxycaching.pdf) provides design
and implementation details.

12.9.2. Proxy Cache Configuration
---------------------------------

The cache configuration specific directives described below must
appear after a overlay pcache directive within a "database meta" or
"database ldap" section of the server's slapd.conf(5) file.

12.9.2.1. Setting cache parameters
----------------------------------

 pcache <DB> <maxentries> <nattrsets> <entrylimit> <period>

This directive enables proxy caching and sets general cache
parameters.  The <DB> parameter specifies which underlying database is
to be used to hold cached entries.  It should be set to mdb.  The
<maxentries> parameter specifies the total number of entries which may
be held in the cache.  The <nattrsets> parameter specifies the total
number of attribute sets (as specified by the pcacheAttrset directive)
that may be defined.  The <entrylimit> parameter specifies the maximum
number of entries in a cacheable query.  The <period> specifies the
consistency check period (in seconds).  In each period, queries with
expired TTLs are removed.

12.9.2.2. Defining attribute sets
---------------------------------

 pcacheAttrset <index> <attrs...>

Used to associate a set of attributes to an index. Each attribute set
is associated with an index number from 0 to <numattrsets>-1. These
indices are used by the pcacheTemplate directive to define cacheable
templates.

12.9.2.3. Specifying cacheable templates
----------------------------------------

 pcacheTemplate <prototype_string> <attrset_index> <TTL>

Specifies a cacheable template and the "time to live" (in sec) <TTL>
for queries belonging to the template. A template is described by its
prototype filter string and set of required attributes identified by
<attrset_index>.

12.9.2.4. Example for slapd.conf
--------------------------------

An example slapd.conf(5) database section for a caching server which
proxies for the "dc=example,dc=com" subtree held at server
ldap.example.com.

        database        ldap
        suffix          "dc=example,dc=com"
        rootdn          "dc=example,dc=com"
        uri             ldap://ldap.example.com/
        overlay pcache
        pcache         mdb 100000 1 1000 100
        pcacheAttrset  0 mail postaladdress telephonenumber
        pcacheTemplate (sn=) 0 3600
        pcacheTemplate (&(sn=)(givenName=)) 0 3600
        pcacheTemplate (&(departmentNumber=)(secretary=*)) 0 3600

        directory ./testrun/db.2.a
        maxsize   1073741824
        index       objectClass eq
        index       cn,sn,uid,mail  pres,eq,sub

12.9.2.5. Example for slapd-config
----------------------------------

The same example as a LDIF file for back-config for a caching server
which proxies for the "dc=example,dc=com" subtree held at server
ldap.example.com.

   dn: olcDatabase={2}ldap,cn=config
   objectClass: olcDatabaseConfig
   objectClass: olcLDAPConfig
   olcDatabase: {2}ldap
   olcSuffix: dc=example,dc=com
   olcRootDN: dc=example,dc=com
   olcDbURI: "ldap://ldap.example.com"

   dn: olcOverlay={0}pcache,olcDatabase={2}ldap,cn=config
   objectClass: olcOverlayConfig
   objectClass: olcPcacheConfig
   olcOverlay: {0}pcache
   olcPcache: mdb 100000 1 1000 100
   olcPcacheAttrset: 0 mail postalAddress telephoneNumber
   olcPcacheTemplate: "(sn=)" 0 3600 0 0 0
   olcPcacheTemplate: "(&(sn=)(givenName=))" 0 3600 0 0 0
   olcPcacheTemplate: "(&(departmentNumber=)(secretary=))" 0 3600

   dn: olcDatabase={0}mdb,olcOverlay={0}pcache,olcDatabase={2}ldap,cn=config
   objectClass: olcMdbConfig
   objectClass: olcPcacheDatabase
   olcDatabase: {0}mdb
   olcDbDirectory: ./testrun/db.2.a
   olcDbMaxSize: 1073741824
   olcDbIndex: objectClass eq
   olcDbIndex: cn,sn,uid,mail  pres,eq,sub

12.9.2.5.1. Cacheable Queries
-----------------------------

A LDAP search query is cacheable when its filter matches one of the
templates as defined in the "pcacheTemplate" statements and when it
references only the attributes specified in the corresponding
attribute set. In the example above the attribute set number 0 defines
that only the attributes: mail postaladdress telephonenumber are
cached for the following pcacheTemplates.

12.9.2.5.2. Examples:
---------------------

        Filter: (&(sn=Richard*)(givenName=jack))
        Attrs: mail telephoneNumber

is cacheable, because it matches the template (&(sn=)(givenName=)) and
its attributes are contained in pcacheAttrset 0.

        Filter: (&(sn=Richard*)(telephoneNumber))
        Attrs: givenName

is not cacheable, because the filter does not match the template, nor
is the attribute givenName stored in the cache

        Filter: (|(sn=Richard*)(givenName=jack))
        Attrs: mail telephoneNumber

is not cacheable, because the filter does not match the template (
logical OR "|" condition instead of logical AND "&" )

12.9.3. Further Information
---------------------------

slapo-pcache(5)

12.10. Password Policies
------------------------

12.10.1. Overview
-----------------

This overlay follows the specifications contained in the draft RFC
titled draft-behera-ldap-password-policy-09. While the draft itself is
expired, it has been implemented in several directory servers,
including slapd. Nonetheless, it is important to note that it is a
draft, meaning that it is subject to change and is a work-in-progress.

The key abilities of the password policy overlay are as follows:

o    Enforce a minimum length for new passwords

o    Make sure passwords are not changed too frequently

o    Cause passwords to expire, provide warnings before they need to
     be changed, and allow a fixed number of 'grace' logins to allow
     them to be changed after they have expired

o    Maintain a history of passwords to prevent password re-use

o    Prevent password guessing by locking a password for a specified
     period of time after repeated authentication failures

o    Force a password to be changed at the next authentication

o    Set an administrative lock on an account

o    Support multiple password policies on a default or a per-object
     basis.

o    Perform arbitrary quality checks using an external loadable
     module. This is a non-standard extension of the draft RFC.

12.10.2. Password Policy Configuration
--------------------------------------

Instantiate the module in the database where it will be used, after
adding the new ppolicy schema and loading the ppolicy module. The
following example shows the ppolicy module being added to the database
that handles the naming context "dc=example,dc=com". In this example
we are also specifying the DN of a policy object to use if none other
is specified in a user's object.

       database mdb
       suffix "dc=example,dc=com"
       [...additional database configuration directives go here...]

       overlay ppolicy
       ppolicy_default "cn=default,ou=policies,dc=example,dc=com"

Now we need a container for the policy objects. In our example the
password policy objects are going to be placed in a section of the
tree called "ou=policies,dc=example,dc=com":

       dn: ou=policies,dc=example,dc=com
       objectClass: organizationalUnit
       objectClass: top
       ou: policies

The default policy object that we are creating defines the following
policies:

o    The user is allowed to change his own password. Note that the
     directory ACLs for this attribute can also affect this ability
     (pwdAllowUserChange: TRUE).

o    The name of the password attribute is "userPassword"
     (pwdAttribute: userPassword). Note that this is the only value
     that is accepted by OpenLDAP for this attribute.

o    The server will check the syntax of the password. If the server
     is unable to check the syntax (i.e., it was hashed or otherwise
     encoded by the client) it will return an error refusing the
     password (pwdCheckQuality: 2).

o    When a client includes the Password Policy Request control with a
     bind request, the server will respond with a password expiration
     warning if it is going to expire in ten minutes or less
     (pwdExpireWarning: 600). The warnings themselves are returned in
     a Password Policy Response control.

o    When the password for a DN has expired, the server will allow
     five additional "grace" logins (pwdGraceAuthNLimit: 5).

o    The server will maintain a history of the last five passwords
     that were used for a DN (pwdInHistory: 5).

o    The server will lock the account after the maximum number of
     failed bind attempts has been exceeded (pwdLockout: TRUE).

o    When the server has locked an account, the server will keep it
     locked until an administrator unlocks it (pwdLockoutDuration: 0)

o    The server will reset its failed bind count after a period of 30
     seconds.

o    Passwords will not expire (pwdMaxAge: 0).

o    Passwords can be changed as often as desired (pwdMinAge: 0).

o    Passwords must be at least 5 characters in length (pwdMinLength:
     5).

o    The password does not need to be changed at the first bind or
     when the administrator has reset the password (pwdMustChange:
     FALSE)

o    The current password does not need to be included with password
     change requests (pwdSafeModify: FALSE)

o    The server will only allow five failed binds in a row for a
     particular DN (pwdMaxFailure: 5).

The actual policy would be:

       dn: cn=default,ou=policies,dc=example,dc=com
       cn: default
       objectClass: pwdPolicy
       objectClass: namedPolicy
       objectClass: top
       pwdAllowUserChange: TRUE
       pwdAttribute: userPassword
       pwdCheckQuality: 2
       pwdExpireWarning: 600
       pwdFailureCountInterval: 30
       pwdGraceAuthNLimit: 5
       pwdInHistory: 5
       pwdLockout: TRUE
       pwdLockoutDuration: 0
       pwdMaxAge: 0
       pwdMaxFailure: 5
       pwdMinAge: 0
       pwdMinLength: 5
       pwdMustChange: FALSE
       pwdSafeModify: FALSE

You can create additional policy objects as needed.

The namedPolicy object class is present because the policy entry
requires a structural object class.

There are two ways password policy can be applied to individual
objects:

1. The pwdPolicySubentry in a user's object - If a user's object has a
pwdPolicySubEntry attribute specifying the DN of a policy object, then
the policy defined by that object is applied.

2. Default password policy - If there is no specific pwdPolicySubentry
set for an object, and the password policy module was configured with
the DN of a default policy object and if that object exists, then the
policy defined in that object is applied.

Please see slapo-ppolicy(5) for a complete explanation of its
features.

A guiding philosophy for OpenLDAP and directory servers in general has
been that they always hand back exactly what they were given, without
modification. For example, if the cn attribute of an object was set to
fOObaR, the server will return that exact string during a search.
Values of attributes of a sensitive nature, such as userPassword, are
often hashed to conceal their values. Since the userPassword values
are used internally by the directory server to authenticate users, any
hash algorithm that is applied to the value must be compatible with
the directory server. Historically this problem has been solved by
making the LDAP client application be able to hash the userPassword
attribute value in a way that is compatible with the directory server,
but this solution has the obvious drawback of requiring tight coupling
between the LDAP client and server, and limits the choices of usable
hashing algorithms to those that are accommodated by both. This is
clearly a sub-optimal solution.

In 2001 RFC 3062 became a standard that specified an LDAP extended
operation for cases like this. Extended operations are not bound by
the return-what-you-are-given philosophy and so are free to do things
to attribute values that the add and modify operations cannot. The
change password extended operation accepts a plaintext password and
hashes it based on a specification that is contained in the server.
This allows the server to be in control of the hashing algorithm
which, in turn, ensures that any hashes applied to userPassword
attribute values will not prevent users from being authenticated.

The password policy module's ppolicy_hash_cleartext flag addresses
this problem by intercepting LDAP modify operations that include the
userPassword attribute and converting them to change password extended
operations so they can be hashed according to the specification
contained in slapd's configuration. When this flag is set, LDAP
applications that modify the userPassword attribute can send the
password in cleartext form to the server using a standard LDAP modify
command and the server will hash the value according to the
password-hash directive before storing it. It goes without saying that
steps need to be taken to protect the cleartext password in transit,
such as using SSL, TLS, or some other link encryption method.

The following example shows the ppolicy module configured to hash
cleartext passwords:

       database mdb
       suffix "dc=example,dc=com"
       [...additional database configuration directives go here...]

       overlay ppolicy
       ppolicy_default "cn=default,ou=policies,dc=example,dc=com"
       ppolicy_hash_cleartext

12.10.3. Further Information
----------------------------

slapo-ppolicy(5)

12.11. Referential Integrity
----------------------------

12.11.1. Overview
-----------------

This overlay can be used with a backend database such as slapd-mdb(5)
to maintain the cohesiveness of a schema which utilizes reference
attributes.

Whenever a modrdn or delete is performed, that is, when an entry's DN
is renamed or an entry is removed, the server will search the
directory for references to this DN (in selected attributes: see
below) and update them accordingly. If it was a delete operation, the
reference is deleted. If it was a modrdn operation, then the reference
is updated with the new DN.

For example, a very common administration task is to maintain group
membership lists, specially when users are removed from the directory.
When an user account is deleted or renamed, all groups this user is a
member of have to be updated. LDAP administrators usually have scripts
for that. But we can use the refint overlay to automate this task. In
this example, if the user is removed from the directory, the overlay
will take care to remove the user from all the groups he/she was a
member of. No more scripting for this.

12.11.2. Referential Integrity Configuration
--------------------------------------------

The configuration for this overlay is as follows:

       overlay refint
       refint_attributes <attribute [attribute ...]>
       refint_nothing <string>

o    refint_attributes: this parameter specifies a space separated
     list of attributes which will have the referential integrity
     maintained. When an entry is removed or has its DN renamed, the
     server will do an internal search for any of the
     refint_attributes that point to the affected DN and update them
     accordingly. IMPORTANT: the attributes listed here must have the
     distinguishedName syntax, that is, hold DNs as values.

o    refint_nothing: some times, while trying to maintain the
     referential integrity, the server has to remove the last
     attribute of its kind from an entry. This may be prohibited by
     the schema: for example, the groupOfNames object class requires
     at least one member. In these cases, the server will add the
     attribute value specified in refint_nothing to the entry.

To illustrate this overlay, we will use the group membership scenario.

In slapd.conf:

       overlay refint
       refint_attributes member
       refint_nothing "cn=admin,dc=example,dc=com"

This configuration tells the overlay to maintain the referential
integrity of the member attribute. This attribute is used in the
groupOfNames object class which always needs a member, so we add the
refint_nothing directive to fill in the group with a standard member
should all the members vanish.

If we have the following group membership, the refint overlay will
automatically remove john from the group if his entry is removed from
the directory:

** Unable to import figure refint.png **

Figure X.Y: Maintaining referential integrity in groups

Notice that if we rename (modrdn) the john entry to, say, jsmith, the
refint overlay will also rename the reference in the member attribute,
so the group membership stays correct.

If we removed all users from the directory who are a member of this
group, then the end result would be a single member in the group:
cn=admin,dc=example,dc=com. This is the refint_nothing parameter
kicking into action so that the schema is not violated.

The rootdn must be set for the database as refint runs as the rootdn
to gain access to make its updates.  The rootpw does not need to be
set.

12.11.3. Further Information
----------------------------

slapo-refint(5)

12.12. Return Code
------------------

12.12.1. Overview
-----------------

This overlay is useful to test the behavior of clients when
server-generated erroneous and/or unusual responses occur, for
example; error codes, referrals, excessive response times and so on.

This would be classed as a debugging tool whilst developing client
software or additional Overlays.

For detailed information, please see the slapo-retcode(5) man page.

12.12.2. Return Code Configuration
----------------------------------

The retcode overlay utilizes the "return code" schema described in the
man page. This schema is specifically designed for use with this
overlay and is not intended to be used otherwise.

Note: The necessary schema is loaded automatically by the overlay.

An example configuration might be:

       overlay         retcode
       retcode-parent  "ou=RetCodes,dc=example,dc=com"
       include         ./retcode.conf

       retcode-item    "cn=Unsolicited"                0x00 unsolicited="0"
       retcode-item    "cn=Notice of Disconnect"       0x00 unsolicited="1.3.6.1.4.1.1466.20036"
       retcode-item    "cn=Pre-disconnect"             0x34 flags="pre-disconnect"
       retcode-item    "cn=Post-disconnect"            0x34 flags="post-disconnect"

Note: retcode.conf can be found in the openldap source at:
tests/data/retcode.conf

An excerpt of a retcode.conf would be something like:

       retcode-item    "cn=success"                            0x00

       retcode-item    "cn=success w/ delay"                   0x00    sleeptime=2

       retcode-item    "cn=operationsError"                    0x01
       retcode-item    "cn=protocolError"                      0x02
       retcode-item    "cn=timeLimitExceeded"                  0x03    op=search
       retcode-item    "cn=sizeLimitExceeded"                  0x04    op=search
       retcode-item    "cn=compareFalse"                       0x05    op=compare
       retcode-item    "cn=compareTrue"                        0x06    op=compare
       retcode-item    "cn=authMethodNotSupported"             0x07
       retcode-item    "cn=strongAuthNotSupported"             0x07    text="same as authMethodNotSupported"
       retcode-item    "cn=strongAuthRequired"                 0x08
       retcode-item    "cn=strongerAuthRequired"               0x08    text="same as strongAuthRequired"

Please see tests/data/retcode.conf for a complete retcode.conf

12.12.3. Further Information
----------------------------

slapo-retcode(5)

12.13. Rewrite/Remap
--------------------

12.13.1. Overview
-----------------

It performs basic DN/data rewrite and objectClass/attributeType
mapping. Its usage is mostly intended to provide virtual views of
existing data either remotely, in conjunction with the proxy backend
described in slapd-ldap(5), or locally, in conjunction with the relay
backend described in slapd-relay(5).

This overlay is extremely configurable and advanced, therefore
recommended reading is the slapo-rwm(5) man page.

12.13.2. Rewrite/Remap Configuration
------------------------------------

12.13.3. Further Information
----------------------------

slapo-rwm(5)

12.14. Sync Provider
--------------------

12.14.1. Overview
-----------------

This overlay implements the provider-side support for the LDAP Content
Synchronization (RFC4533) as well as syncrepl replication support,
including persistent search functionality.

12.14.2. Sync Provider Configuration
------------------------------------

There is very little configuration needed for this overlay, in fact
for many situations merely loading the overlay will suffice.

However, because the overlay creates a contextCSN attribute in the
root entry of the database which is updated for every write operation
performed against the database and only updated in memory, it is
recommended to configure a checkpoint so that the contextCSN is
written into the underlying database to minimize recovery time after
an unclean shutdown:

       overlay syncprov
       syncprov-checkpoint 100 10

For every 100 operations or 10 minutes, which ever is sooner, the
contextCSN will be checkpointed.

The four configuration directives available are syncprov-checkpoint,
syncprov-sessionlog, syncprov-nopresent and syncprov-reloadhint which
are covered in the man page discussing various other scenarios where
this overlay can be used.

12.14.3. Further Information
----------------------------

The slapo-syncprov(5) man page and the Configuring the different
replication types section

12.15. Translucent Proxy
------------------------

12.15.1. Overview
-----------------

This overlay can be used with a backend database such as slapd-mdb(5)
to create a "translucent proxy".

Entries retrieved from a remote LDAP server may have some or all
attributes overridden, or new attributes added, by entries in the
local database before being presented to the client.

A search operation is first populated with entries from the remote
LDAP server, the attributes of which are then overridden with any
attributes defined in the local database. Local overrides may be
populated with the add, modify, and modrdn operations, the use of
which is restricted to the root user of the translucent local
database.

A compare operation will perform a comparison with attributes defined
in the local database record (if any) before any comparison is made
with data in the remote database.

12.15.2. Translucent Proxy Configuration
----------------------------------------

There are various options available with this overlay, but for this
example we will demonstrate adding new attributes to a remote entry
and also searching against these newly added local attributes. For
more information about overriding remote entries and search
configuration, please see slapo-translucent(5)

Note: The Translucent Proxy overlay will disable schema checking in
the local database, so that an entry consisting of overlay attributes
need not adhere to the complete schema.

First we configure the overlay in the normal manner:

       include     /usr/local/etc/openldap/schema/core.schema
       include     /usr/local/etc/openldap/schema/cosine.schema
       include     /usr/local/etc/openldap/schema/nis.schema
       include     /usr/local/etc/openldap/schema/inetorgperson.schema

       pidfile     ./slapd.pid
       argsfile    ./slapd.args

       database    mdb
       suffix      "dc=suretecsystems,dc=com"
       rootdn      "cn=trans,dc=suretecsystems,dc=com"
       rootpw      secret
       directory   ./openldap-data

       index       objectClass eq

       overlay     translucent
       translucent_local carLicense

       uri         ldap://192.168.X.X:389
       lastmod     off
       acl-bind    binddn="cn=admin,dc=suretecsystems,dc=com" credentials="blahblah"

You will notice the overlay directive and a directive to say what
attribute we want to be able to search against in the local database.
We must also load the ldap backend which will connect to the remote
directory server.

Now we take an example LDAP group:

       # itsupport, Groups, suretecsystems.com
       dn: cn=itsupport,ou=Groups,dc=suretecsystems,dc=com
       objectClass: posixGroup
       objectClass: sambaGroupMapping
       cn: itsupport
       gidNumber: 1000
       sambaSID: S-1-5-21-XXX
       sambaGroupType: 2
       displayName: itsupport
       memberUid: ghenry
       memberUid: joebloggs

and create an LDIF file we can use to add our data to the local
database, using some pretty strange choices of new attributes for
demonstration purposes:

       [ghenry@suretec test_configs]$ cat test-translucent-add.ldif
       dn: cn=itsupport,ou=Groups,dc=suretecsystems,dc=com
       businessCategory: frontend-override
       carLicense: LIVID
       employeeType: special
       departmentNumber: 9999999
       roomNumber: 41L-535

Searching against the proxy gives:

       [ghenry@suretec test_configs]$ ldapsearch -x -H ldap://127.0.0.1:9001 "(cn=itsupport)"
       # itsupport, Groups, OxObjects, suretecsystems.com
       dn: cn=itsupport,ou=Groups,ou=OxObjects,dc=suretecsystems,dc=com
       objectClass: posixGroup
       objectClass: sambaGroupMapping
       cn: itsupport
       gidNumber: 1003
       SAMBASID: S-1-5-21-XXX
       SAMBAGROUPTYPE: 2
       displayName: itsupport
       memberUid: ghenry
       memberUid: joebloggs
       roomNumber: 41L-535
       departmentNumber: 9999999
       employeeType: special
       carLicense: LIVID
       businessCategory: frontend-override

Here we can see that the 5 new attributes are added to the remote
entry before being returned to the our client.

Because we have configured a local attribute to search against:

       overlay     translucent
       translucent_local carLicense

we can also search for that to return the completely fabricated entry:

       ldapsearch -x -H ldap://127.0.0.1:9001 (carLicense=LIVID)

This is an extremely useful feature because you can then extend a
remote directory server locally and also search against the local
entries.

Note: Because the translucent overlay does not perform any DN
rewrites, the local and remote database instances must have the same
suffix. Other configurations will probably fail with No Such Object
and other errors

12.15.3. Further Information
----------------------------

slapo-translucent(5)

12.16. Attribute Uniqueness
---------------------------

12.16.1. Overview
-----------------

This overlay can be used with a backend database such as slapd-mdb(5)
to enforce the uniqueness of some or all attributes within a subtree.

12.16.2. Attribute Uniqueness Configuration
-------------------------------------------

This overlay is only effective on new data from the point the overlay
is enabled. To check uniqueness for existing data, you can export and
import your data again via the LDAP Add operation, which will not be
suitable for large amounts of data, unlike slapcat.

For the following example, if uniqueness were enforced for the mail
attribute, the subtree would be searched for any other records which
also have a mail attribute containing the same value presented with an
add, modify or modrdn operation which are unique within the configured
scope. If any are found, the request is rejected.

Note: If no attributes are specified, for example ldap:///??sub?, then
the URI applies to all non-operational attributes. However, the
keyword ignore can be specified to exclude certain non-operational
attributes.

To search at the base dn of the current backend database ensuring
uniqueness of the mail attribute, we simply add the following
configuration:

       overlay unique
       unique_uri ldap:///?mail?sub?

For an existing entry of:

       dn: cn=gavin,dc=suretecsystems,dc=com
       objectClass: top
       objectClass: inetorgperson
       cn: gavin
       sn: henry
       mail: ghenry@suretecsystems.com

and we then try to add a new entry of:

       dn: cn=robert,dc=suretecsystems,dc=com
       objectClass: top
       objectClass: inetorgperson
       cn: robert
       sn: jones
       mail: ghenry@suretecsystems.com

would result in an error like so:

       adding new entry "cn=robert,dc=example,dc=com"
       ldap_add: Constraint violation (19)
               additional info: some attributes not unique

The overlay can have multiple URIs specified within a domain, allowing
complex selections of objects and also have multiple unique_uri
statements or olcUniqueURI attributes which will create independent
domains.

For more information and details about the strict and ignore keywords,
please see the slapo-unique(5) man page.

12.16.3. Further Information
----------------------------

slapo-unique(5)

12.17. Value Sorting
--------------------

12.17.1. Overview
-----------------

The Value Sorting overlay can be used with a backend database to sort
the values of specific multi-valued attributes within a subtree. The
sorting occurs whenever the attributes are returned in a search
response.

12.17.2. Value Sorting Configuration
------------------------------------

Sorting can be specified in ascending or descending order, using
either numeric or alphanumeric sort methods. Additionally, a
"weighted" sort can be specified, which uses a numeric weight
prepended to the attribute values.

The weighted sort is always performed in ascending order, but may be
combined with the other methods for values that all have equal
weights. The weight is specified by prepending an integer weight
{<weight>} in front of each value of the attribute for which weighted
sorting is desired. This weighting factor is stripped off and never
returned in search results.

Here are a few examples:

       loglevel    sync stats

       database    mdb
       suffix      "dc=suretecsystems,dc=com"
       directory   /usr/local/var/openldap-data

       ......

       overlay valsort
       valsort-attr memberUid ou=Groups,dc=suretecsystems,dc=com alpha-ascend

For example, ascend:

       # sharedemail, Groups, suretecsystems.com
       dn: cn=sharedemail,ou=Groups,dc=suretecsystems,dc=com
       objectClass: posixGroup
       objectClass: top
       cn: sharedemail
       gidNumber: 517
       memberUid: admin
       memberUid: dovecot
       memberUid: laura
       memberUid: suretec

For weighted, we change our data to:

       # sharedemail, Groups, suretecsystems.com
       dn: cn=sharedemail,ou=Groups,dc=suretecsystems,dc=com
       objectClass: posixGroup
       objectClass: top
       cn: sharedemail
       gidNumber: 517
       memberUid: {4}admin
       memberUid: {2}dovecot
       memberUid: {1}laura
       memberUid: {3}suretec

and change the config to:

       overlay valsort
       valsort-attr memberUid ou=Groups,dc=suretecsystems,dc=com weighted

Searching now results in:

       # sharedemail, Groups, OxObjects, suretecsystems.com
       dn: cn=sharedemail,ou=Groups,ou=OxObjects,dc=suretecsystems,dc=com
       objectClass: posixGroup
       objectClass: top
       cn: sharedemail
       gidNumber: 517
       memberUid: laura
       memberUid: dovecot
       memberUid: suretec
       memberUid: admin

12.17.3. Further Information
----------------------------

slapo-valsort(5)

12.18. Overlay Stacking
-----------------------

12.18.1. Overview
-----------------

Overlays can be stacked, which means that more than one overlay can be
instantiated for each database, or for the frontend. As a consequence,
each overlays function is called, if defined, when overlay execution
is invoked. Multiple overlays are executed in reverse order (as a
stack) with respect to their definition in slapd.conf (5), or with
respect to their ordering in the config database, as documented in
slapd-config (5).

12.18.2. Example Scenarios
--------------------------

12.18.2.1. Samba
----------------


13. Schema Specification
========================

This chapter describes how to extend the user schema used by slapd(8).
 The chapter assumes the reader is familiar with the LDAP/X.500
information model.

The first section, Distributed Schema Files details optional schema
definitions provided in the distribution and where to obtain other
definitions. The second section, Extending Schema, details how to
define new schema items.

This chapter does not discuss how to extend system schema used by
slapd(8) as this requires source code modification.  System schema
includes all operational attribute types or any object class which
allows or requires an operational attribute (directly or indirectly).

13.1. Distributed Schema Files
------------------------------

OpenLDAP Software is distributed with a set of schema specifications
for your use.  Each set is defined in a file suitable for inclusion
(using the include directive) in your slapd.conf(5) file.  These
schema files are normally installed in the
/usr/local/etc/openldap/schema directory.

Table 8.1: Provided Schema Specifications

File                                                      Description
.................................. .................................. 
core.schema                                  OpenLDAP core (required)
cosine.schema                      Cosine and Internet X.500 (useful)
inetorgperson.schema                           InetOrgPerson (useful)
misc.schema                                   Assorted (experimental)
nis.schema                         Network Information Services (FYI)
openldap.schema                       OpenLDAP Project (experimental)

To use any of these schema files, you only need to include the desired
file in the global definitions portion of your slapd.conf(5) file. 
For example:

        # include schema
        include /usr/local/etc/openldap/schema/core.schema
        include /usr/local/etc/openldap/schema/cosine.schema
        include /usr/local/etc/openldap/schema/inetorgperson.schema

Additional files may be available.  Please consult the OpenLDAP FAQ
(http://www.openldap.org/faq/).

Note: You should not modify any of the schema items defined in
provided files.

13.2. Extending Schema
----------------------

Schema used by slapd(8) may be extended to support additional
syntaxes, matching rules, attribute types, and object classes.  This
chapter details how to add user application attribute types and object
classes using the syntaxes and matching rules already supported by
slapd.  slapd can also be extended to support additional syntaxes,
matching rules and system schema, but this requires some programming
and hence is not discussed here.

There are five steps to defining new schema:

1.   obtain Object Identifier

2.   choose a name prefix

3.   create local schema file

4.   define custom attribute types (if necessary)

5.   define custom object classes

13.2.1. Object Identifiers
--------------------------

Each schema element is identified by a globally unique Object
Identifier (OID).  OIDs are also used to identify other objects.  They
are commonly found in protocols described by ASN.1.  In particular,
they are heavily used by the Simple Network Management Protocol
(SNMP). As OIDs are hierarchical, your organization can obtain one OID
and branch it as needed.  For example, if your organization were
assigned OID 1.1, you could branch the tree as follows:

Table 8.2: Example OID hierarchy

OID                                                        Assignment
.................................. .................................. 
1.1                                                Organization's OID
1.1.1                                                   SNMP Elements
1.1.2                                                   LDAP Elements
1.1.2.1                                                AttributeTypes
1.1.2.1.1                                              x-my-Attribute
1.1.2.2                                                 ObjectClasses
1.1.2.2.1                                            x-my-ObjectClass

You are, of course, free to design a hierarchy suitable to your
organizational needs under your organization's OID. No matter what
hierarchy you choose, you should maintain a registry of assignments
you make.  This can be a simple flat file or something more
sophisticated such as the OpenLDAP OID Registry
(http://www.openldap.org/faq/index.cgi?file=197).

For more information about Object Identifiers (and a listing service)
see http://www.alvestrand.no/objectid/.

     Under no circumstances should you hijack OID namespace!

To obtain a registered OID at no cost, apply for a OID under the
Internet Assigned Numbers Authority (ORG:IANA) maintained Private
Enterprise arc. Any private enterprise (organization) may request a
Private Enterprise Number (PEN) to be assigned under this arc. Just
fill out the IANA form at http://pen.iana.org/pen/PenApplication.page
and your official PEN will be sent to you usually within a few days.
Your base OID will be something like 1.3.6.1.4.1.X where X is an
integer.

Note: PENs obtained using this form may be used for any purpose
including identifying LDAP schema elements.

Alternatively, OID name space may be available from a national
authority (e.g., ANSI, BSI).

13.2.2. Naming Elements
-----------------------

In addition to assigning a unique object identifier to each schema
element, you should provide at least one textual name for each
element.  Names should be registered with the IANA or prefixed with
"x-" to place in the "private use" name space.

The name should be both descriptive and not likely to clash with names
of other schema elements.  In particular, any name you choose should
not clash with present or future Standard Track names (this is assured
if you registered names or use names beginning with "x-").

It is noted that you can obtain your own registered name prefix so as
to avoid having to register your names individually. See RFC4520 for
details.

In the examples below, we have used a short prefix 'x-my-'. Such a
short prefix would only be suitable for a very large, global
organization.  In general, we recommend something like 'x-de-Firm-'
(German company) or 'x-com-Example' (elements associated with
organization associated with example.com).

13.2.3. Local schema file
-------------------------

The objectclass and attributeTypes configuration file directives can
be used to define schema rules on entries in the directory.  It is
customary to create a file to contain definitions of your custom
schema items.  We recommend you create a file local.schema in
/usr/local/etc/openldap/schema/local.schema and then include this file
in your slapd.conf(5) file immediately after other schema include
directives.

        # include schema
        include /usr/local/etc/openldap/schema/core.schema
        include /usr/local/etc/openldap/schema/cosine.schema
        include /usr/local/etc/openldap/schema/inetorgperson.schema
        # include local schema
        include /usr/local/etc/openldap/schema/local.schema

13.2.4. Attribute Type Specification
------------------------------------

The attributetype directive is used to define a new attribute type. 
The directive uses the same Attribute Type Description (as defined in
RFC4512) used by the attributeTypes attribute found in the subschema
subentry, e.g.:

        attributetype <RFC4512 Attribute Type Description>

where Attribute Type Description is defined by the following ABNF:

      AttributeTypeDescription = "(" whsp
            numericoid whsp              ; AttributeType identifier
          [ "NAME" qdescrs ]             ; name used in AttributeType
          [ "DESC" qdstring ]            ; description
          [ "OBSOLETE" whsp ]
          [ "SUP" woid ]                 ; derived from this other
                                         ; AttributeType
          [ "EQUALITY" woid              ; Matching Rule name
          [ "ORDERING" woid              ; Matching Rule name
          [ "SUBSTR" woid ]              ; Matching Rule name
          [ "SYNTAX" whsp noidlen whsp ] ; Syntax OID
          [ "SINGLE-VALUE" whsp ]        ; default multi-valued
          [ "COLLECTIVE" whsp ]          ; default not collective
          [ "NO-USER-MODIFICATION" whsp ]; default user modifiable
          [ "USAGE" whsp AttributeUsage ]; default userApplications
          whsp ")"

      AttributeUsage =
          "userApplications"     /
          "directoryOperation"   /
          "distributedOperation" / ; DSA-shared
          "dSAOperation"          ; DSA-specific, value depends on server


where whsp is a space (' '), numericoid is a globally unique OID in
dotted-decimal form (e.g. 1.1.0), qdescrs is one or more names, woid
is either the name or OID optionally followed by a length specifier
(e.g {10}).

For example, the attribute types name and cn are defined in
core.schema as:

        attributeType ( 2.5.4.41 NAME 'name'
                DESC 'name(s) associated with the object'
                EQUALITY caseIgnoreMatch
                SUBSTR caseIgnoreSubstringsMatch
                SYNTAX 1.3.6.1.4.1.1466.115.121.1.15{32768} )
        attributeType ( 2.5.4.3 NAME ( 'cn' 'commonName' )
                DESC 'common name(s) associated with the object'
                SUP name )

Notice that each defines the attribute's OID, provides a short name,
and a brief description.  Each name is an alias for the OID. slapd(8)
returns the first listed name when returning results.

The first attribute, name, holds values of directoryString (UTF-8
encoded Unicode) syntax.  The syntax is specified by OID
(1.3.6.1.4.1.1466.115.121.1.15 identifies the directoryString syntax).
 A length recommendation of 32768 is specified.  Servers should
support values of this length, but may support longer values. The
field does NOT specify a size constraint, so is ignored on servers
(such as slapd) which don't impose such size limits.  In addition, the
equality and substring matching uses case ignore rules.  Below are
tables listing commonly used syntax and matching rules (slapd(8)
supports these and many more).

Table 8.3: Commonly Used Syntaxes

Name                   OID                     Description
...................... ....................... ...................... 
boolean                1.3.6.1.4.1.1466.115.121.1.7 boolean value
directoryString        1.3.6.1.4.1.1466.115.121.1.15 Unicode (UTF-8) string
distinguishedName      1.3.6.1.4.1.1466.115.121.1.12 LDAP DN
integer                1.3.6.1.4.1.1466.115.121.1.27 integer
numericString          1.3.6.1.4.1.1466.115.121.1.36 numeric string
OID                    1.3.6.1.4.1.1466.115.121.1.38 object identifier
octetString            1.3.6.1.4.1.1466.115.121.1.40 arbitrary octets



Table 8.4: Commonly Used Matching Rules

Name                   Type                    Description
...................... ....................... ...................... 
booleanMatch           equality                boolean
caseIgnoreMatch        equality                case insensitive,
                                               space insensitive
caseIgnoreOrderingMatch ordering               case insensitive,
                                               space insensitive
caseIgnoreSubstringsMatch substrings           case insensitive,
                                               space insensitive
caseExactMatch         equality                case sensitive, space
                                               insensitive
caseExactOrderingMatch ordering                case sensitive, space
                                               insensitive
caseExactSubstringsMatch substrings            case sensitive, space
                                               insensitive
distinguishedNameMatch equality                distinguished name
integerMatch           equality                integer
integerOrderingMatch   ordering                integer
numericStringMatch     equality                numerical
numericStringOrderingMatch ordering            numerical
numericStringSubstringsMatch substrings        numerical
octetStringMatch       equality                octet string
octetStringOrderingMatch ordering              octet string
octetStringSubstringsMatch octet st            ring
ordering
objectIdentiferMatch   equality                object identifier

The second attribute, cn, is a subtype of name hence it inherits the
syntax, matching rules, and usage of name. commonName is an
alternative name.

Neither attribute is restricted to a single value.  Both are meant for
usage by user applications.  Neither is obsolete nor collective.

The following subsections provide a couple of examples.

13.2.4.1. x-my-UniqueName
-------------------------

Many organizations maintain a single unique name for each user. Though
one could use displayName (RFC2798), this attribute is really meant to
be controlled by the user, not the organization.  We could just copy
the definition of displayName from inetorgperson.schema and replace
the OID, name, and description, e.g:

        attributetype ( 1.1.2.1.1 NAME 'x-my-UniqueName'
                DESC 'unique name with my organization'
                EQUALITY caseIgnoreMatch
                SUBSTR caseIgnoreSubstringsMatch
                SYNTAX 1.3.6.1.4.1.1466.115.121.1.15
                SINGLE-VALUE )

However, if we want this name to be used in name assertions, e.g.
(name=*Jane*), the attribute could alternatively be defined as a
subtype of name, e.g.:

        attributetype ( 1.1.2.1.1 NAME 'x-my-UniqueName'
                DESC 'unique name with my organization'
                SUP name )

13.2.4.2. x-my-Photo
--------------------

Many organizations maintain a photo of each each user.  A x-my-Photo
attribute type could be defined to hold a photo. Of course, one could
use just use jpegPhoto (RFC2798) (or a subtype) to hold the photo. 
However, you can only do this if the photo is in JPEG File Interchange
Format. Alternatively, an attribute type which uses the Octet String
syntax can be defined, e.g.:

        attributetype ( 1.1.2.1.2 NAME 'x-my-Photo'
                DESC 'a photo (application defined format)'
                SYNTAX 1.3.6.1.4.1.1466.115.121.1.40
                SINGLE-VALUE )

In this case, the syntax doesn't specify the format of the photo. It's
assumed (maybe incorrectly) that all applications accessing this
attribute agree on the handling of values.

If you wanted to support multiple photo formats, you could define a
separate attribute type for each format, prefix the photo with some
typing information, or describe the value using ASN.1 and use the
;binary transfer option.

Another alternative is for the attribute to hold a URI pointing to the
photo.  You can model such an attribute after labeledURI (RFC2079) or
simply create a subtype, e.g.:

        attributetype ( 1.1.2.1.3 NAME 'x-my-PhotoURI'
                DESC 'URI and optional label referring to a photo'
                SUP labeledURI )

13.2.5. Object Class Specification
----------------------------------

The objectclasses directive is used to define a new object class.  The
directive uses the same Object Class Description (as defined in
RFC4512) used by the objectClasses attribute found in the subschema
subentry, e.g.:

        objectclass <RFC4512 Object Class Description>

where Object Class Description is defined by the following ABNF:

        ObjectClassDescription = "(" whsp
                numericoid whsp      ; ObjectClass identifier
                [ "NAME" qdescrs ]
                [ "DESC" qdstring ]
                [ "OBSOLETE" whsp ]
                [ "SUP" oids ]       ; Superior ObjectClasses
                [ ( "ABSTRACT" / "STRUCTURAL" / "AUXILIARY" ) whsp ]
                        ; default structural
                [ "MUST" oids ]      ; AttributeTypes
                [ "MAY" oids ]       ; AttributeTypes
                whsp ")"

where whsp is a space (' '), numericoid is a globally unique OID in
dotted-decimal form (e.g. 1.1.0), qdescrs is one or more names, and
oids is one or more names and/or OIDs.

13.2.5.1. x-my-PhotoObject
--------------------------

To define an auxiliary object class which allows x-my-Photo to be
added to any existing entry.

        objectclass ( 1.1.2.2.1 NAME 'x-my-PhotoObject'
                DESC 'mixin x-my-Photo'
                AUXILIARY
                MAY x-my-Photo )

13.2.5.2. x-my-Person
---------------------

If your organization would like have a private structural object class
to instantiate users, you can subclass one of the existing person
classes, such as inetOrgPerson (RFC2798), and add any additional
attributes which you desire.

        objectclass ( 1.1.2.2.2 NAME 'x-my-Person'
                DESC 'my person'
                SUP inetOrgPerson
                MUST ( x-my-UniqueName $ givenName )
                MAY x-my-Photo )

The object class inherits the required/allowed attribute types of
inetOrgPerson but requires x-my-UniqueName and givenName and allows
x-my-Photo.

13.2.6. OID Macros
------------------

To ease the management and use of OIDs, slapd(8) supports Object
Identifier macros.  The objectIdentifier directive is used to equate a
macro (name) with a OID.  The OID may possibly be derived from a
previously defined OID macro.   The slapd.conf(5) syntax is:

        objectIdentifier <name> { <oid> | <name>[:<suffix>] }

The following demonstrates definition of a set of OID macros and their
use in defining schema elements:

        objectIdentifier myOID  1.1
        objectIdentifier mySNMP myOID:1
        objectIdentifier myLDAP myOID:2
        objectIdentifier myAttributeType        myLDAP:1
        objectIdentifier myObjectClass  myLDAP:2
        attributetype ( myAttributeType:3 NAME 'x-my-PhotoURI'
                DESC 'URI and optional label referring to a photo'
                SUP labeledURI )
        objectclass ( myObjectClass:1 NAME 'x-my-PhotoObject'
                DESC 'mixin x-my-Photo'
                AUXILIARY
                MAY x-my-Photo )


14. Security Considerations
===========================

OpenLDAP Software is designed to run in a wide variety of computing
environments from tightly-controlled closed networks to the global
Internet.  Hence, OpenLDAP Software supports many different security
mechanisms.  This chapter describes these mechanisms and discusses
security considerations for using OpenLDAP Software.

14.1. Network Security
----------------------

14.1.1. Selective Listening
---------------------------

By default, slapd(8) will listen on both the IPv4 and IPv6 "any"
addresses.  It is often desirable to have slapd listen on select
address/port pairs.  For example, listening only on the IPv4 address
127.0.0.1 will disallow remote access to the directory server. E.g.:

        slapd -h ldap://127.0.0.1

While the server can be configured to listen on a particular interface
address, this doesn't necessarily restrict access to the server to
only those networks accessible via that interface.   To selective
restrict remote access, it is recommend that an IP Firewall be used to
restrict access.

See Command-line Options and slapd(8) for more information.

14.1.2. IP Firewall
-------------------

IP firewall capabilities of the server system can be used to restrict
access based upon the client's IP address and/or network interface
used to communicate with the client.

Generally, slapd(8) listens on port 389/tcp for ldap:// sessions and
port 636/tcp for ldaps://) sessions.  slapd(8) may be configured to
listen on other ports.

As specifics of how to configure IP firewall are dependent on the
particular kind of IP firewall used, no examples are provided here.
See the document associated with your IP firewall.

14.1.3. TCP Wrappers
--------------------

slapd(8) supports TCP Wrappers.  TCP Wrappers provide a rule-based
access control system for controlling TCP/IP access to the server. 
For example, the host_options(5) rule:

        slapd: 10.0.0.0/255.0.0.0 127.0.0.1 : ALLOW
        slapd: ALL : DENY

allows only incoming connections from the private network 10.0.0.0 and
localhost (127.0.0.1) to access the directory service.

Note: IP addresses are used as slapd(8) is not normally configured to
perform reverse lookups.

It is noted that TCP wrappers require the connection to be accepted.
As significant processing is required just to deny a connection, it is
generally advised that IP firewall protection be used instead of TCP
wrappers.

See hosts_access(5) for more information on TCP wrapper rules.

14.2. Data Integrity and Confidentiality Protection
---------------------------------------------------

Transport Layer Security (TLS) can be used to provide data integrity
and confidentiality protection.  OpenLDAP supports negotiation of TLS
(SSL) via both StartTLS and ldaps://. See the Using TLS chapter for
more information.  StartTLS is the standard track mechanism.

A number of Simple Authentication and Security Layer (SASL)
mechanisms, such as DIGEST-MD5 and GSSAPI, also provide data integrity
and confidentiality protection.  See the Using SASL chapter for more
information.

14.2.1. Security Strength Factors
---------------------------------

The server uses Security Strength Factors (SSF) to indicate the
relative strength of protection.  A SSF of zero (0) indicates no
protections are in place.  A SSF of one (1) indicates integrity
protection are in place.  A SSF greater than one (>1) roughly
correlates to the effective encryption key length.  For example, DES
is 56, 3DES is 112, and AES 128, 192, or 256.

A number of administrative controls rely on SSFs associated with TLS
and SASL protection in place on an LDAP session.

security controls disallow operations when appropriate protections are
not in place.  For example:

        security ssf=1 update_ssf=112

requires integrity protection for all operations and encryption
protection, 3DES equivalent, for update operations (e.g. add, delete,
modify, etc.).  See slapd.conf(5) for details.

For fine-grained control, SSFs may be used in access controls. See the
Access Control section for more information.

14.3. Authentication Methods
----------------------------

14.3.1. "simple" method
-----------------------

The LDAP "simple" method has three modes of operation:

o    anonymous,

o    unauthenticated, and

o    user/password authenticated.

Anonymous access is requested by providing no name and no password to
the "simple" bind operation.  Unauthenticated access is requested by
providing a name but no password.  Authenticated access is requested
by providing a valid name and password.

An anonymous bind results in an anonymous authorization association. 
Anonymous bind mechanism is enabled by default, but can be disabled by
specifying "disallow bind_anon" in slapd.conf(5).

Note: Disabling the anonymous bind mechanism does not prevent
anonymous access to the directory. To require authentication to access
the directory, one should instead specify "require authc".

An unauthenticated bind also results in an anonymous authorization
association.  Unauthenticated bind mechanism is disabled by default,
but can be enabled by specifying "allow bind_anon_cred" in
slapd.conf(5).  As a number of LDAP applications mistakenly generate
unauthenticated bind request when authenticated access was intended
(that is, they do not ensure a password was provided), this mechanism
should generally remain disabled.

A successful user/password authenticated bind results in a user
authorization identity, the provided name, being associated with the
session.  User/password authenticated bind is enabled by default.
However, as this mechanism itself offers no eavesdropping protection
(e.g., the password is set in the clear), it is recommended that it be
used only in tightly controlled systems or when the LDAP session is
protected by other means (e.g., TLS, IPsec). Where the administrator
relies on TLS to protect the password, it is recommended that
unprotected authentication be disabled.  This is done using the
security directive's simple_bind option, which provides fine grain
control over the level of confidential protection to require for
simple user/password authentication. E.g., using security
simple_bind=56 would require simple binds to use encryption of DES
equivalent or better.

The user/password authenticated bind mechanism can be completely
disabled by setting "disallow bind_simple".

Note: An unsuccessful bind always results in the session having an
anonymous authorization association.

14.3.2. SASL method
-------------------

The LDAP SASL method allows the use of any SASL authentication
mechanism. The Using SASL section discusses the use of SASL.

14.4. Password Storage
----------------------

LDAP passwords are normally stored in the userPassword attribute.
RFC4519 specifies that passwords are not stored in encrypted (or
hashed) form.  This allows a wide range of password-based
authentication mechanisms, such as DIGEST-MD5 to be used. This is also
the most interoperable storage scheme.

However, it may be desirable to store a hash of password instead.
slapd(8) supports a variety of storage schemes for the administrator
to choose from.

Note: Values of password attributes, regardless of storage scheme
used, should be protected as if they were clear text.  Hashed
passwords are subject to dictionary attacks and brute-force attacks.

The userPassword attribute is allowed to have more than one value, and
it is possible for each value to be stored in a different form. During
authentication, slapd will iterate through the values until it finds
one that matches the offered password or until it runs out of values
to inspect.  The storage scheme is stored as a prefix on the value, so
a hashed password using the Salted SHA1 (SSHA) scheme looks like:

 userPassword: {SSHA}DkMTwBl+a/3DQTxCYEApdUtNXGgdUac3

The advantage of hashed passwords is that an attacker which discovers
the hash does not have direct access to the actual password.
Unfortunately, as dictionary and brute force attacks are generally
quite easy for attackers to successfully mount, this advantage is
marginal at best (this is why all modern Unix systems use shadow
password files).

The disadvantages of hashed storage is that they are non-standard, may
cause interoperability problem, and generally preclude the use of
stronger than Simple (or SASL/PLAIN) password-based authentication
mechanisms such as DIGEST-MD5.

14.4.1. SSHA password storage scheme
------------------------------------

This is the salted version of the SHA scheme. It is believed to be the
most secure password storage scheme supported by slapd.

These values represent the same password:

 userPassword: {SSHA}DkMTwBl+a/3DQTxCYEApdUtNXGgdUac3
 userPassword: {SSHA}d0Q0626PSH9VUld7yWpR0k6BlpQmtczb

14.4.2. CRYPT password storage scheme
-------------------------------------

This scheme uses the operating system's crypt(3) hash function. It
normally produces the traditional Unix-style 13 character hash, but on
systems with glibc2 it can also generate the more secure 34-byte MD5
hash.

 userPassword: {CRYPT}aUihad99hmev6
 userPassword: {CRYPT}$1$czBJdDqS$TmkzUAb836oMxg/BmIwN.1

The advantage of the CRYPT scheme is that passwords can be transferred
to or from an existing Unix password file without having to know the
cleartext form. Both forms of crypt include salt so they have some
resistance to dictionary attacks.

Note: Since this scheme uses the operating system's crypt(3) hash
function, it is therefore operating system specific.

14.4.3. MD5 password storage scheme
-----------------------------------

This scheme simply takes the MD5 hash of the password and stores it in
base64 encoded form:

 userPassword: {MD5}Xr4ilOzQ4PCOq3aQ0qbuaQ==

Although safer than cleartext storage, this is not a very secure
scheme. The MD5 algorithm is fast, and because there is no salt the
scheme is vulnerable to a dictionary attack.

14.4.4. SMD5 password storage scheme
------------------------------------

This improves on the basic MD5 scheme by adding salt (random data
which means that there are many possible representations of a given
plaintext password). For example, both of these values represent the
same password:

 userPassword: {SMD5}4QWGWZpj9GCmfuqEvm8HtZhZS6E=
 userPassword: {SMD5}g2/J/7D5EO6+oPdklp5p8YtNFk4=

14.4.5. SHA password storage scheme
-----------------------------------

Like the MD5 scheme, this simply feeds the password through an SHA
hash process. SHA is thought to be more secure than MD5, but the lack
of salt leaves the scheme exposed to dictionary attacks.

 userPassword: {SHA}5en6G6MezRroT3XKqkdPOmY/BfQ=

14.4.6. SASL password storage scheme
------------------------------------

This is not really a password storage scheme at all. It uses the value
of the userPassword attribute to delegate password verification to
another process. See below for more information.

Note: This is not the same as using SASL to authenticate the LDAP
session.

14.5. Pass-Through authentication
---------------------------------

Since OpenLDAP 2.0 slapd has had the ability to delegate password
verification to a separate process. This uses the sasl_checkpass(3)
function so it can use any back-end server that Cyrus SASL supports
for checking passwords. The choice is very wide, as one option is to
use saslauthd(8) which in turn can use local files, Kerberos, an IMAP
server, another LDAP server, or anything supported by the PAM
mechanism.

The server must be built with the --enable-spasswd configuration
option to enable pass-through authentication.

Note: This is not the same as using a SASL mechanism to authenticate
the LDAP session.

Pass-Through authentication works only with plaintext passwords, as
used in the "simple bind" and "SASL PLAIN" authentication mechanisms.

Pass-Through authentication is selective: it only affects users whose
userPassword attribute has a value marked with the "{SASL}" scheme.
The format of the attribute is:

 userPassword: {SASL}username@realm

The username and realm are passed to the SASL authentication mechanism
and are used to identify the account whose password is to be verified.
This allows arbitrary mapping between entries in OpenLDAP and accounts
known to the backend authentication service.

It would be wise to use access control to prevent users from changing
their passwords through LDAP where they have pass-through
authentication enabled.

14.5.1. Configuring slapd to use an authentication provider
-----------------------------------------------------------

Where an entry has a "{SASL}" password value, OpenLDAP delegates the
whole process of validating that entry's password to Cyrus SASL. All
the configuration is therefore done in SASL config files.

The first file to be considered is confusingly named slapd.conf and is
typically found in the SASL library directory, often
/usr/lib/sasl2/slapd.conf This file governs the use of SASL when
talking LDAP to slapd as well as the use of SASL backends for
pass-through authentication. See options.html in the Cyrus SASL docs
for full details. Here is a simple example for a server that will use
saslauthd to verify passwords:

 mech_list: plain
 pwcheck_method: saslauthd
 saslauthd_path: /var/run/sasl2/mux

14.5.2. Configuring saslauthd
-----------------------------

saslauthd is capable of using many different authentication services:
see saslauthd(8) for details. A common requirement is to delegate some
or all authentication to another LDAP server. Here is a sample
saslauthd.conf that uses Microsoft Active Directory (AD):

 ldap_servers: ldap://dc1.example.com/ ldap://dc2.example.com/

 ldap_search_base: cn=Users,DC=ad,DC=example,DC=com
 ldap_filter: (userPrincipalName=%u)

 ldap_bind_dn: cn=saslauthd,cn=Users,DC=ad,DC=example,DC=com
 ldap_password: secret

In this case, saslauthd is run with the ldap authentication mechanism
and is set to combine the SASL realm with the login name:

 saslauthd -a ldap -r

This means that the "username@realm" string from the userPassword
attribute ends up being used to search AD for
"userPrincipalName=username@realm" - the password is then verified by
attempting to bind to AD using the entry found by the search and the
password supplied by the LDAP client.

14.5.3. Testing pass-through authentication
-------------------------------------------

It is usually best to start with the back-end authentication provider
and work through saslauthd and slapd towards the LDAP client.

In the AD example above, first check that the DN and password that
saslauthd will use when it connects to AD are valid:

 ldapsearch -x -H ldap://dc1.example.com/ \
      -D cn=saslauthd,cn=Users,DC=ad,DC=example,DC=com \
      -w secret \
      -b '' \
      -s base

Next check that a sample AD user can be found:

 ldapsearch -x -H ldap://dc1.example.com/ \
      -D cn=saslauthd,cn=Users,DC=ad,DC=example,DC=com \
      -w secret \
      -b cn=Users,DC=ad,DC=example,DC=com \
      "(userPrincipalName=user@ad.example.com)"

Check that the user can bind to AD:

 ldapsearch -x -H ldap://dc1.example.com/ \
      -D cn=user,cn=Users,DC=ad,DC=example,DC=com \
      -w userpassword \
      -b cn=user,cn=Users,DC=ad,DC=example,DC=com \
      -s base \
        "(objectclass=*)"

If all that works then saslauthd should be able to do the same:

 testsaslauthd -u user@ad.example.com -p userpassword
 testsaslauthd -u user@ad.example.com -p wrongpassword

Now put the magic token into an entry in OpenLDAP:

 userPassword: {SASL}user@ad.example.com

It should now be possible to bind to OpenLDAP using the DN of that
entry and the password of the AD user.


15. Using SASL
==============

OpenLDAP clients and servers are capable of authenticating via the
Simple Authentication and Security Layer (SASL) framework, which is
detailed in RFC4422.   This chapter describes how to make use of SASL
in OpenLDAP.

There are several industry standard authentication mechanisms that can
be used with SASL, including GSSAPI for Kerberos V, DIGEST-MD5, and
PLAIN and EXTERNAL for use with Transport Layer Security (TLS).

The standard client tools provided with OpenLDAP Software, such as
ldapsearch(1) and ldapmodify(1), will by default attempt to
authenticate the user to the LDAP directory server using SASL.  Basic
authentication service can be set up by the LDAP administrator with a
few steps, allowing users to be authenticated to the slapd server as
their LDAP entry.  With a few extra steps, some users and services can
be allowed to exploit SASL's proxy authorization feature, allowing
them to authenticate themselves and then switch their identity to that
of another user or service.

This chapter assumes you have read Cyrus SASL for System
Administrators, provided with the Cyrus SASL package (in
doc/sysadmin.html) and have a working Cyrus SASL installation.  You
should use the Cyrus SASL sample_client and sample_server to test your
SASL installation before attempting to make use of it with OpenLDAP
Software.

Note that in the following text the term user is used to describe a
person or application entity who is connecting to the LDAP server via
an LDAP client, such as ldapsearch(1).  That is, the term user not
only applies to both an individual using an LDAP client, but to an
application entity which issues LDAP client operations without direct
user control.  For example, an e-mail server which uses LDAP
operations to access information held in an LDAP server is an
application entity.

15.1. SASL Security Considerations
----------------------------------

SASL offers many different authentication mechanisms.  This section
briefly outlines security considerations.

Some mechanisms, such as PLAIN and LOGIN, offer no greater security
over LDAP simple authentication.  Like LDAP simple authentication,
such mechanisms should not be used unless you have adequate security
protections in place.  It is recommended that these mechanisms be used
only in conjunction with Transport Layer Security (TLS).  Use of PLAIN
and LOGIN are not discussed further in this document.

The DIGEST-MD5 mechanism is the mandatory-to-implement authentication
mechanism for LDAPv3.  Though DIGEST-MD5 is not a strong
authentication mechanism in comparison with trusted third party
authentication systems (such as Kerberos or public key systems), it
does offer significant protections against a number of attacks. 
Unlike the CRAM-MD5 mechanism, it prevents chosen plaintext attacks. 
DIGEST-MD5 is favored over the use of plaintext password mechanisms. 
The CRAM-MD5 mechanism is deprecated in favor of DIGEST-MD5.  Use of
DIGEST-MD5 is discussed below.

The GSSAPI mechanism utilizes GSS-API Kerberos V to provide secure
authentication services.  The KERBEROS_V4 mechanism is available for
those using Kerberos IV.  Kerberos is viewed as a secure, distributed
authentication system suitable for both small and large enterprises. 
Use of GSSAPI and KERBEROS_V4 are discussed below.

The EXTERNAL mechanism utilizes authentication services provided by
lower level network services such as Transport Layer Security (TLS). 
When used in conjunction with TLS X.509-based public key technology,
EXTERNAL offers strong authentication. TLS is discussed in the Using
TLS chapter.

EXTERNAL can also be used with the ldapi:/// transport, as Unix-domain
sockets can report the UID and GID of the client process.

There are other strong authentication mechanisms to choose from,
including OTP (one time passwords) and SRP (secure remote passwords). 
These mechanisms are not discussed in this document.

15.2. SASL Authentication
-------------------------

Getting basic SASL authentication running involves a few steps. The
first step configures your slapd server environment so that it can
communicate with client programs using the security system in place at
your site. This usually involves setting up a service key, a public
key, or other form of secret. The second step concerns mapping
authentication identities to LDAP DN's, which depends on how entries
are laid out in your directory. An explanation of the first step will
be given in the next section using Kerberos V4 as an example
mechanism. The steps necessary for your site's authentication
mechanism will be similar, but a guide to every mechanism available
under SASL is beyond the scope of this chapter. The second step is
described in the section Mapping Authentication Identities.

15.2.1. GSSAPI
--------------

This section describes the use of the SASL GSSAPI mechanism and
Kerberos V with OpenLDAP.  It will be assumed that you have Kerberos V
deployed, you are familiar with the operation of the system, and that
your users are trained in its use.  This section also assumes you have
familiarized yourself with the use of the GSSAPI mechanism by reading
Configuring GSSAPI and Cyrus SASL (provided with Cyrus SASL in the
doc/gssapi file) and successfully experimented with the Cyrus provided
sample_server and sample_client applications.  General information
about Kerberos is available at http://web.mit.edu/kerberos/www/.

To use the GSSAPI mechanism with slapd(8) one must create a service
key with a principal for ldap service within the realm for the host on
which the service runs.  For example, if you run slapd on
directory.example.com and your realm is EXAMPLE.COM, you need to
create a service key with the principal:

        ldap/directory.example.com@EXAMPLE.COM

When slapd(8) runs, it must have access to this key.  This is
generally done by placing the key into a keytab file,
/etc/krb5.keytab.  See your Kerberos and Cyrus SASL documentation for
information regarding keytab location settings.

To use the GSSAPI mechanism to authenticate to the directory, the user
obtains a Ticket Granting Ticket (TGT) prior to running the LDAP
client.  When using OpenLDAP client tools, the user may mandate use of
the GSSAPI mechanism by specifying -Y GSSAPI as a command option.

For the purposes of authentication and authorization, slapd(8)
associates an authentication request DN of the form:

        uid=<primary[/instance][@realm]>,cn=gssapi,cn=auth

The realm is omitted by Cyrus SASL if it's equal to the default realm
of the server in /etc/krb5.conf.

Continuing our example, a user with the Kerberos principal
kurt@EXAMPLE.COM would have the associated DN:

        uid=kurt,cn=gssapi,cn=auth

and the principal ursula/admin@FOREIGN.REALM would have the associated
DN:

        uid=ursula/admin@foreign.realm,cn=gssapi,cn=auth

The authentication request DN can be used directly in ACLs and
groupOfNames "member" attributes, since it is of legitimate LDAP DN
format.  Or alternatively, the authentication DN could be mapped
before use.  See the section Mapping Authentication Identities for
details.

If you configure the olcSaslRealm then it will be inserted as an extra
component in the authorization DN, regardless of any Kerberos realms
in use. For example, if you set olcSaslRealm to example.com then you
will get:

        uid=kurt,cn=example.com,cn=gssapi,cn=auth
        uid=ursula/admin@foreign.realm,cn=example.com,cn=gssapi,cn=auth

15.2.2. KERBEROS_V4
-------------------

This section describes the use of the SASL KERBEROS_V4 mechanism with
OpenLDAP.  It will be assumed that you are familiar with the workings
of the Kerberos IV security system, and that your site has Kerberos IV
deployed.  Your users should be familiar with authentication policy,
how to receive credentials in a Kerberos ticket cache, and how to
refresh expired credentials.

Note: KERBEROS_V4 and Kerberos IV are deprecated in favor of GSSAPI
and Kerberos V.

Client programs will need to be able to obtain a session key for use
when connecting to your LDAP server. This allows the LDAP server to
know the identity of the user, and allows the client to know it is
connecting to a legitimate server. If encryption layers are to be
used, the session key can also be used to help negotiate that option.

The slapd server runs the service called "ldap", and the server will
require a srvtab file with a service key.  SASL aware client programs
will be obtaining an "ldap" service ticket with the user's ticket
granting ticket (TGT), with the instance of the ticket matching the
hostname of the OpenLDAP server. For example, if your realm is named
EXAMPLE.COM and the slapd server is running on the host named
directory.example.com, the /etc/srvtab file on the server will have a
service key

        ldap.directory@EXAMPLE.COM

When an LDAP client is authenticating a user to the directory using
the KERBEROS_IV mechanism, it will request a session key for that same
principal, either from the ticket cache or by obtaining a new one from
the Kerberos server.  This will require the TGT to be available and
valid in the cache as well.  If it is not present or has expired, the
client may print out the message:

        ldap_sasl_interactive_bind_s: Local error

When the service ticket is obtained, it will be passed to the LDAP
server as proof of the user's identity.  The server will extract the
identity and realm out of the service ticket using SASL library calls,
and convert them into an authentication request DN of the form

        uid=<username>,cn=<realm>,cn=<mechanism>,cn=auth

So in our above example, if the user's name were "adamson", the
authentication request DN would be:

        uid=adamson,cn=example.com,cn=kerberos_v4,cn=auth

This authentication request DN can be used directly ACLs or,
alternatively, mapped prior to use.  See the section Mapping
Authentication Identities for details.

15.2.3. DIGEST-MD5
------------------

This section describes the use of the SASL DIGEST-MD5 mechanism using
secrets stored either in the directory itself or in Cyrus SASL's own
database. DIGEST-MD5 relies on the client and the server sharing a
"secret", usually a password. The server generates a challenge and the
client a response proving that it knows the shared secret. This is
much more secure than simply sending the secret over the wire.

Cyrus SASL supports several shared-secret mechanisms. To do this, it
needs access to the plaintext password (unlike mechanisms which pass
plaintext passwords over the wire, where the server can store a hashed
version of the password).

The server's copy of the shared-secret may be stored in Cyrus SASL's
own sasldb database, in an external system accessed via saslauthd, or
in LDAP database itself.  In either case it is very important to apply
file access controls and LDAP access controls to prevent exposure of
the passwords.  The configuration and commands discussed in this
section assume the use of Cyrus SASL 2.1.

To use secrets stored in sasldb, simply add users with the saslpasswd2
command:

       saslpasswd2 -c <username>

The passwords for such users must be managed with the saslpasswd2
command.

To use secrets stored in the LDAP directory, place plaintext passwords
in the userPassword attribute.  It will be necessary to add an option
to slapd.conf to make sure that passwords set using the LDAP Password
Modify Operation are stored in plaintext:

       password-hash   {CLEARTEXT}

Passwords stored in this way can be managed either with ldappasswd(1)
or by simply modifying the userPassword attribute.  Regardless of
where the passwords are stored, a mapping will be needed from
authentication request DN to user's DN.

The DIGEST-MD5 mechanism produces authentication IDs of the form:

        uid=<username>,cn=<realm>,cn=digest-md5,cn=auth

If the default realm is used, the realm name is omitted from the ID,
giving:

        uid=<username>,cn=digest-md5,cn=auth

See Mapping Authentication Identities below for information on
optional mapping of identities.

With suitable mappings in place, users can specify SASL IDs when
performing LDAP operations, and the password stored in sasldb or in
the directory itself will be used to verify the authentication. For
example, the user identified by the directory entry:

       dn: cn=Andrew Findlay+uid=u000997,dc=example,dc=com
       objectclass: inetOrgPerson
       objectclass: person
       sn: Findlay
       uid: u000997
       userPassword: secret

can issue commands of the form:

       ldapsearch -Y DIGEST-MD5 -U u000997 ...

Note: in each of the above cases, no authorization identity (e.g. -X)
was provided.   Unless you are attempting SASL Proxy Authorization, no
authorization identity should be specified. The server will infer an
authorization identity from authentication identity (as described
below).

15.2.4. EXTERNAL
----------------

The SASL EXTERNAL mechanism makes use of an authentication performed
by a lower-level protocol: usually TLS or Unix IPC

Each transport protocol returns Authentication Identities in its own
format:

15.2.4.1. TLS Authentication Identity Format
--------------------------------------------

This is the Subject DN from the client-side certificate. Note that DNs
are displayed differently by LDAP and by X.509, so a certificate
issued to

        C=gb, O=The Example Organisation, CN=A Person

will produce an authentication identity of:

        cn=A Person,o=The Example Organisation,c=gb

Note that you must set a suitable value for TLSVerifyClient to make
the server request the use of a client-side certificate. Without this,
the SASL EXTERNAL mechanism will not be offered. Refer to the Using
TLS chapter for details.

15.2.4.2. IPC (ldapi:///) Identity Format
-----------------------------------------

This is formed from the Unix UID and GID of the client process:

        gidNumber=<number>+uidNumber=<number>,cn=peercred,cn=external,cn=auth

Thus, a client process running as root will be:

        gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth

15.2.5. Mapping Authentication Identities
-----------------------------------------

The authentication mechanism in the slapd server will use SASL library
calls to obtain the authenticated user's "username", based on whatever
underlying authentication mechanism was used.  This username is in the
namespace of the authentication mechanism, and not in the normal LDAP
namespace. As stated in the sections above, that username is
reformatted into an authentication request DN of the form

        uid=<username>,cn=<realm>,cn=<mechanism>,cn=auth

or

        uid=<username>,cn=<mechanism>,cn=auth

depending on whether or not <mechanism> employs the concept of
"realms".  Note also that the realm part will be omitted if the
default realm was used in the authentication.

The ldapwhoami(1) command may be used to determine the identity
associated with the user.  It is very useful for determining proper
function of mappings.

It is not intended that you should add LDAP entries of the above form
to your LDAP database.  Chances are you have an LDAP entry for each of
the persons that will be authenticating to LDAP, laid out in your
directory tree, and the tree does not start at cn=auth. But if your
site has a clear mapping between the "username" and an LDAP entry for
the person, you will be able to configure your LDAP server to
automatically map a authentication request DN to the user's
authentication DN.

Note: it is not required that the authentication request DN nor the
user's authentication DN resulting from the mapping refer to an entry
held in the directory.  However, additional capabilities become
available (see below).

The LDAP administrator will need to tell the slapd server how to map
an authentication request DN to a user's authentication DN. This is
done by adding one or more authz-regexp directives to the
slapd.conf(5) file.  This directive takes two arguments:

        authz-regexp   <search pattern>   <replacement pattern>

The authentication request DN is compared to the search pattern using
the regular expression functions regcomp() and regexec(), and if it
matches, it is rewritten as the replacement pattern. If there are
multiple authz-regexp directives, only the first whose search pattern
matches the authentication identity is used. The string that is output
from the replacement pattern should be the authentication DN of the
user or an LDAP URL.  If replacement string produces a DN, the entry
named by this DN need not be held by this server.  If the replace
string produces an LDAP URL, that LDAP URL must evaluate to one and
only one entry held by this server.

The search pattern can contain any of the regular expression
characters listed in regexec(3C). The main characters of note are dot
".", asterisk "*", and the open and close parenthesis "(" and ")". 
Essentially, the dot matches any character, the asterisk allows zero
or more repeats of the immediately preceding character or pattern, and
terms in parenthesis are remembered for the replacement pattern.

The replacement pattern will produce either a DN or URL referring to
the user.  Anything from the authentication request DN that matched a
string in parenthesis in the search pattern is stored in the variable
"$1". That variable "$1" can appear in the replacement pattern, and
will be replaced by the string from the authentication request DN. If
there were multiple sets of parentheses in the search pattern, the
variables $2, $3, etc are used.

15.2.6. Direct Mapping
----------------------

Where possible, direct mapping of the authentication request DN to the
user's DN is generally recommended.  Aside from avoiding the expense
of searching for the user's DN, it allows mapping to DNs which refer
to entries not held by this server.

Suppose the authentication request DN is written as:

        uid=adamson,cn=example.com,cn=gssapi,cn=auth

and the user's actual LDAP entry is:

        uid=adamson,ou=people,dc=example,dc=com

then the following authz-regexp directive in slapd.conf(5) would
provide for direct mapping.

        authz-regexp
          uid=([^,]*),cn=example.com,cn=gssapi,cn=auth
          uid=$1,ou=people,dc=example,dc=com

An even more lenient rule could be written as

        authz-regexp
          uid=([^,]*),cn=[^,]*,cn=auth
          uid=$1,ou=people,dc=example,dc=com

Be careful about setting the search pattern too leniently, however,
since it may mistakenly allow persons to become authenticated as a DN
to which they should not have access.  It is better to write several
strict directives than one lenient directive which has security holes.
 If there is only one authentication mechanism in place at your site,
and zero or one realms in use, you might be able to map between
authentication identities and LDAP DN's with a single authz-regexp
directive.

Don't forget to allow for the case where the realm is omitted as well
as the case with an explicitly specified realm. This may well require
a separate authz-regexp directive for each case, with the
explicit-realm entry being listed first.

15.2.7. Search-based mappings
-----------------------------

There are a number of cases where mapping to a LDAP URL may be
appropriate.  For instance, some sites may have person objects located
in multiple areas of the LDAP tree, such as if there were an
ou=accounting tree and an ou=engineering tree, with persons
interspersed between them.  Or, maybe the desired mapping must be
based upon information in the user's information. Consider the need to
map the above authentication request DN to user whose entry is as
follows:

        dn: cn=Mark Adamson,ou=People,dc=Example,dc=COM
        objectclass: person
        cn: Mark Adamson
        uid: adamson

The information in the authentication request DN is insufficient to
allow the user's DN to be directly derived, instead the user's DN must
be searched for.  For these situations, a replacement pattern which
produces a LDAP URL can be used in the authz-regexp directives.  This
URL will then be used to perform an internal search of the LDAP
database to find the person's authentication DN.

An LDAP URL, similar to other URL's, is of the form

        ldap://<host>/<base>?<attrs>?<scope>?<filter>

This contains all of the elements necessary to perform an LDAP search:
 the name of the server <host>, the LDAP DN search base <base>, the
LDAP attributes to retrieve <attrs>, the search scope <scope> which is
one of the three options "base", "one", or "sub", and lastly an LDAP
search filter <filter>.  Since the search is for an LDAP DN within the
current server, the <host> portion should be empty.  The <attrs> field
is also ignored since only the DN is of concern.  These two elements
are left in the format of the URL to maintain the clarity of what
information goes where in the string.

Suppose that the person in the example from above did in fact have an
authentication username of "adamson" and that information was kept in
the attribute "uid" in their LDAP entry. The authz-regexp directive
might be written as

        authz-regexp
          uid=([^,]*),cn=example.com,cn=gssapi,cn=auth
          ldap:///ou=people,dc=example,dc=com??one?(uid=$1)

This will initiate an internal search of the LDAP database inside the
slapd server. If the search returns exactly one entry, it is accepted
as being the DN of the user. If there are more than one entries
returned, or if there are zero entries returned, the authentication
fails and the user's connection is left bound as the authentication
request DN.

The attributes that are used in the search filter <filter> in the URL
should be indexed to allow faster searching. If they are not, the
authentication step alone can take uncomfortably long periods, and
users may assume the server is down.

A more complex site might have several realms in use, each mapping to
a different subtree in the directory.  These can be handled with
statements of the form:

        # Match Engineering realm
        authz-regexp
           uid=([^,]*),cn=engineering.example.com,cn=digest-md5,cn=auth
           ldap:///dc=eng,dc=example,dc=com??one?(&(uid=$1)(objectClass=person))

        # Match Accounting realm
        authz-regexp
           uid=([^,].*),cn=accounting.example.com,cn=digest-md5,cn=auth
           ldap:///dc=accounting,dc=example,dc=com??one?(&(uid=$1)(objectClass=person))

        # Default realm is customers.example.com
        authz-regexp
           uid=([^,]*),cn=digest-md5,cn=auth
           ldap:///dc=customers,dc=example,dc=com??one?(&(uid=$1)(objectClass=person))

Note that the explicitly-named realms are handled first, to avoid the
realm name becoming part of the UID.  Also note the use of scope and
filters to limit matching to desirable entries.

Note as well that authz-regexp internal search are subject to access
controls.  Specifically, the authentication identity must have auth
access.

See slapd.conf(5) for more detailed information.

15.3. SASL Proxy Authorization
------------------------------

The SASL offers a feature known as proxy authorization, which allows
an authenticated user to request that they act on the behalf of
another user.  This step occurs after the user has obtained an
authentication DN, and involves sending an authorization identity to
the server. The server will then make a decision on whether or not to
allow the authorization to occur. If it is allowed, the user's LDAP
connection is switched to have a binding DN derived from the
authorization identity, and the LDAP session proceeds with the access
of the new authorization DN.

The decision to allow an authorization to proceed depends on the rules
and policies of the site where LDAP is running, and thus cannot be
made by SASL alone. The SASL library leaves it up to the server to
make the decision. The LDAP administrator sets the guidelines of who
can authorize to what identity by adding information into the LDAP
database entries. By default, the authorization features are disabled,
and must be explicitly configured by the LDAP administrator before
use.

The rules governing proxy authorization are not just used for SASL:
they also control the use of the LDAP Proxied Authorization Control
(RFC 4370).

15.3.1. Uses of Proxy Authorization
-----------------------------------

This sort of service is useful when one entity needs to act on the
behalf of many other users. For example, users may be directed to a
web page to make changes to their personal information in their LDAP
entry. The users authenticate to the web server to establish their
identity, but the web server CGI cannot authenticate to the LDAP
server as that user to make changes for them. Instead, the web server
authenticates itself to the LDAP server as a service identity, say,

        cn=WebUpdate,dc=example,dc=com

and then it will SASL authorize to the DN of the user. Once so
authorized, the CGI makes changes to the LDAP entry of the user, and
as far as the slapd server can tell for its ACLs, it is the user
themself on the other end of the connection. The user could have
connected to the LDAP server directly and authenticated as themself,
but that would require the user to have more knowledge of LDAP
clients, knowledge which the web page provides in an easier format.

Proxy authorization can also be used to limit access to an account
that has greater access to the database. Such an account, perhaps even
the root DN specified in slapd.conf(5), can have a strict list of
people who can authorize to that DN. Changes to the LDAP database
could then be only allowed by that DN, and in order to become that DN,
users must first authenticate as one of the persons on the list. This
allows for better auditing of who made changes to the LDAP database. 
If people were allowed to authenticate directly to the privileged
account, possibly through the rootpw slapd.conf(5) directive or
through a userPassword attribute, then auditing becomes more
difficult.

Note that after a successful proxy authorization, the original
authentication DN of the LDAP connection is overwritten by the new DN
from the authorization request. If a service program is able to
authenticate itself as its own authentication DN and then authorize to
other DN's, and it is planning on switching to several different
identities during one LDAP session, it will need to authenticate
itself each time before authorizing to another DN (or use a different
proxy authorization mechanism).  The slapd server does not keep record
of the service program's ability to switch to other DN's. On
authentication mechanisms like Kerberos this will not require multiple
connections being made to the Kerberos server, since the user's TGT
and "ldap" session key are valid for multiple uses for the several
hours of the ticket lifetime.

15.3.2. SASL Authorization Identities
-------------------------------------

The SASL authorization identity is sent to the LDAP server via the -X
switch for ldapsearch(1) and other tools, or in the *authzid parameter
to the lutil_sasl_defaults() call. The identity can be in one of two
forms, either

        u:<username>

or

        dn:<dn>

In the first form, the <username> is from the same namespace as the
authentication identities above. It is the user's username as it is
referred to by the underlying authentication mechanism. Authorization
identities of this form are converted into a DN format by the same
function that the authentication process used, producing an
authorization request DN of the form

        uid=<username>,cn=<realm>,cn=<mechanism>,cn=auth

That authorization request DN is then run through the same
authz-regexp process to convert it into a legitimate authorization DN
from the database. If it cannot be converted due to a failed search
from an LDAP URL, the authorization request fails with "inappropriate
access".  Otherwise, the DN string is now a legitimate authorization
DN ready to undergo approval.

If the authorization identity was provided in the second form, with a
"dn:" prefix, the string after the prefix is already in authorization
DN form, ready to undergo approval.

15.3.3. Proxy Authorization Rules
---------------------------------

Once slapd has the authorization DN, the actual approval process
begins. There are two attributes that the LDAP administrator can put
into LDAP entries to allow authorization:

        authzTo
        authzFrom

Both can be multivalued.  The authzTo attribute is a source rule, and
it is placed into the entry associated with the authentication DN to
tell what authorization DNs the authenticated DN is allowed to assume.
 The second attribute is a destination rule, and it is placed into the
entry associated with the requested authorization DN to tell which
authenticated DNs may assume it.

The choice of which authorization policy attribute to use is up to the
administrator.  Source rules are checked first in the person's
authentication DN entry, and if none of the authzTo rules specify the
authorization is permitted, the authzFrom rules in the authorization
DN entry are then checked. If neither case specifies that the request
be honored, the request is denied. Since the default behavior is to
deny authorization requests, rules only specify that a request be
allowed; there are no negative rules telling what authorizations to
deny.

The value(s) in the two attributes are of the same form as the output
of the replacement pattern of a authz-regexp directive: either a DN or
an LDAP URL. For example, if a authzTo value is a DN, that DN is one
the authenticated user can authorize to. On the other hand, if the
authzTo value is an LDAP URL, the URL is used as an internal search of
the LDAP database, and the authenticated user can become ANY DN
returned by the search. If an LDAP entry looked like:

        dn: cn=WebUpdate,dc=example,dc=com
        authzTo: ldap:///dc=example,dc=com??sub?(objectclass=person)

then any user who authenticated as cn=WebUpdate,dc=example,dc=com
could authorize to any other LDAP entry under the search base
dc=example,dc=com which has an objectClass of Person.

15.3.3.1. Notes on Proxy Authorization Rules
--------------------------------------------

An LDAP URL in a authzTo or authzFrom attribute will return a set of
DNs.  Each DN returned will be checked.  Searches which return a large
set can cause the authorization process to take an uncomfortably long
time. Also, searches should be performed on attributes that have been
indexed by slapd.

To help produce more sweeping rules for authzFrom and authzTo, the
values of these attributes are allowed to be DNs with regular
expression characters in them. This means a source rule like

        authzTo: dn.regex:^uid=[^,]*,dc=example,dc=com$

would allow that authenticated user to authorize to any DN that
matches the regular expression pattern given. This regular expression
comparison can be evaluated much faster than an LDAP search for
(uid=*).

Also note that the values in an authorization rule must be one of the
two forms: an LDAP URL or a DN (with or without regular expression
characters). Anything that does not begin with "ldap://" is taken as a
DN. It is not permissible to enter another authorization identity of
the form "u:<username>" as an authorization rule.

15.3.3.2. Policy Configuration
------------------------------

The decision of which type of rules to use, authzFrom or authzTo, will
depend on the site's situation. For example, if the set of people who
may become a given identity can easily be written as a search filter,
then a single destination rule could be written. If the set of people
is not easily defined by a search filter, and the set of people is
small, it may be better to write a source rule in the entries of each
of those people who should be allowed to perform the proxy
authorization.

By default, processing of proxy authorization rules is disabled. The
authz-policy directive must be set in the slapd.conf(5) file to enable
authorization. This directive can be set to none for no rules (the
default), to for source rules, from for destination rules, or both for
both source and destination rules.

Source rules are extremely powerful. If ordinary users have access to
write the authzTo attribute in their own entries, then they can write
rules that would allow them to authorize as anyone else.  As such,
when using source rules, the authzTo attribute should be protected
with an ACL that only allows privileged users to set its values.

15.3.3.3. Access Control requirements
-------------------------------------

When checking whether a particular DN may authorize as another DN, the
server applies access control rules to the authzTo and authzFrom
attributes. The auth privilege is required for an attribute to be
used.

For example, suppose Alice has authenticated using her own ID and
password, and wants to perform an LDAP operation using Bob's
permissions. If authorization is granted by an authzTo attribute in
Alice's entry then Alice needs the auth privilege on that attribute.
Similarly, if authorization is granted by an authzFrom attribute in
Bob's entry then Alice needs the auth privilege on that. Alice does
not need any other access privilege to do a proxy operation.


16. Using TLS
=============

OpenLDAP clients and servers are capable of using the Transport Layer
Security (TLS) framework to provide integrity and confidentiality
protections and to support LDAP authentication using the SASL EXTERNAL
mechanism. TLS is defined in RFC4346.

Note: For generating certificates, please reference
http://www.openldap.org/faq/data/cache/185.html

16.1. TLS Certificates
----------------------

TLS uses X.509 certificates to carry client and server identities. 
All servers are required to have valid certificates, whereas client
certificates are optional.  Clients must have a valid certificate in
order to authenticate via SASL EXTERNAL. For more information on
creating and managing certificates, see the OpenSSL or GnuTLS
documentation, depending on which TLS implementation libraries you are
using.

16.1.1. Server Certificates
---------------------------

The DN of a server certificate must use the CN attribute to name the
server, and the CN must carry the server's fully qualified domain
name. Additional alias names and wildcards may be present in the
subjectAltName certificate extension.  More details on server
certificate names are in RFC4513.

16.1.2. Client Certificates
---------------------------

The DN of a client certificate can be used directly as an
authentication DN. Since X.509 is a part of the X.500 standard and
LDAP is also based on X.500, both use the same DN formats and
generally the DN in a user's X.509 certificate should be identical to
the DN of their LDAP entry. However, sometimes the DNs may not be
exactly the same, and so the mapping facility described in Mapping
Authentication Identities can be applied to these DNs as well.

16.2. TLS Configuration
-----------------------

After obtaining the required certificates, a number of options must be
configured on both the client and the server to enable TLS and make
use of the certificates.  At a minimum, the clients must be configured
with the name of the file containing all of the Certificate Authority
(CA) certificates it will trust. The server must be configured with
the CA certificates and also its own server certificate and private
key.

Typically a single CA will have issued the server certificate and all
of the trusted client certificates, so the server only needs to trust
that one signing CA. However, a client may wish to connect to a
variety of secure servers managed by different organizations, with
server certificates generated by many different CAs. As such, a client
is likely to need a list of many different trusted CAs in its
configuration.

16.2.1. Server Configuration
----------------------------

The configuration directives for slapd belong in the global directives
section of slapd.conf(5).

16.2.1.1. TLSCACertificateFile <filename>
-----------------------------------------

This directive specifies the PEM-format file containing certificates
for the CA's that slapd will trust. The certificate for the CA that
signed the server certificate must be included among these
certificates. If the signing CA was not a top-level (root) CA,
certificates for the entire sequence of CA's from the signing CA to
the top-level CA should be present. Multiple certificates are simply
appended to the file; the order is not significant.

16.2.1.2. TLSCACertificatePath <path>
-------------------------------------

This directive specifies the path of a directory that contains
individual CA certificates in separate files.  In addition, this
directory must be specially managed using the OpenSSL rehash command.
When using this feature, the OpenSSL library will attempt to locate
certificate files based on a hash of their name and serial number. The
OpenSSL rehash command is used to generate symbolic links with the
hashed names that point to the actual certificate files. As such, this
option can only be used with a filesystem that actually supports
symbolic links. In general, it is simpler to use the
TLSCACertificateFile directive instead.

16.2.1.3. TLSCertificateFile <filename>
---------------------------------------

This directive specifies the file that contains the slapd server
certificate. Certificates are generally public information and require
no special protection.

16.2.1.4. TLSCertificateKeyFile <filename>
------------------------------------------

This directive specifies the file that contains the private key that
matches the certificate stored in the TLSCertificateFile file. Private
keys themselves are sensitive data and are usually password encrypted
for protection. However, the current implementation doesn't support
encrypted keys so the key must not be encrypted and the file itself
must be protected carefully.

16.2.1.5. TLSCipherSuite <cipher-suite-spec>
--------------------------------------------

This directive configures what ciphers will be accepted and the
preference order. <cipher-suite-spec> should be a cipher specification
for OpenSSL. You can use the command

        openssl ciphers -v ALL

to obtain a verbose list of available cipher specifications.

Besides the individual cipher names, the specifiers HIGH, MEDIUM, LOW,
EXPORT, and EXPORT40 may be helpful, along with TLSv1, SSLv3, and
SSLv2.

To obtain the list of ciphers in GnuTLS use:

        gnutls-cli -l

16.2.1.6. TLSRandFile <filename>
--------------------------------

This directive specifies the file to obtain random bits from when
/dev/urandom is not available. If the system provides /dev/urandom
then this option is not needed, otherwise a source of random data must
be configured.  Some systems (e.g. Linux) provide /dev/urandom by
default, while others (e.g. Solaris) require the installation of a
patch to provide it, and others may not support it at all. In the
latter case, EGD or PRNGD should be installed, and this directive
should specify the name of the EGD/PRNGD socket. The environment
variable RANDFILE can also be used to specify the filename. Also, in
the absence of these options, the .rnd file in the slapd user's home
directory may be used if it exists. To use the .rnd file, just create
the file and copy a few hundred bytes of arbitrary data into the file.
The file is only used to provide a seed for the pseudo-random number
generator, and it doesn't need very much data to work.

This directive is ignored with GnuTLS.

16.2.1.7. TLSDHParamFile <filename>
-----------------------------------

This directive specifies the file that contains parameters for
Diffie-Hellman ephemeral key exchange.  This is required in order to
use DHE-based cipher suites, including all DSA-based suites (i.e.
TLSCertificateKeyFile points to a DSA key), and RSA when the 'key
encipherment' key usage is not specified in the certificate. 
Parameters can be generated using the following command

        openssl dhparam [-dsaparam] -out <filename> <numbits> or
        certtool --generate-dh-params --bits <numbits> --outfile <filename>

16.2.1.8. TLSECName <name>
--------------------------

This directive specifies the curve to use for Elliptic Curve
Diffie-Hellman ephemeral key exchange.  This option is only needed to
use ECDHE-based cipher suites in OpenSSL.  The names of supported
curves may be shown using the following command

        openssl ecparam -list_curves

See the OpenSSL documentation for details. This directive is not used
for GnuTLS. For GnuTLS the curves may be specified in the ciphersuite.

16.2.1.9. TLSVerifyClient { never | allow | try | demand }
----------------------------------------------------------

This directive specifies what checks to perform on client certificates
in an incoming TLS session, if any. This option is set to never by
default, in which case the server never asks the client for a
certificate. With a setting of allow the server will ask for a client
certificate; if none is provided the session proceeds normally. If a
certificate is provided but the server is unable to verify it, the
certificate is ignored and the session proceeds normally, as if no
certificate had been provided. With a setting of try the certificate
is requested, and if none is provided, the session proceeds normally.
If a certificate is provided and it cannot be verified, the session is
immediately terminated. With a setting of demand the certificate is
requested and a valid certificate must be provided, otherwise the
session is immediately terminated.

Note: The server must request a client certificate in order to use the
SASL EXTERNAL authentication mechanism with a TLS session. As such, a
non-default TLSVerifyClient setting must be configured before SASL
EXTERNAL authentication may be attempted, and the SASL EXTERNAL
mechanism will only be offered to the client if a valid client
certificate was received.

16.2.2. Client Configuration
----------------------------

Most of the client configuration directives parallel the server
directives. The names of the directives are different, and they go
into ldap.conf(5) instead of slapd.conf(5), but their functionality is
mostly the same. Also, while most of these options may be configured
on a system-wide basis, they may all be overridden by individual users
in their .ldaprc files.

The LDAP Start TLS operation is used in LDAP to initiate TLS
negotiation.  All OpenLDAP command line tools support a -Z and -ZZ
flag to indicate whether a Start TLS operation is to be issued.  The
latter flag indicates that the tool is to cease processing if TLS
cannot be started while the former allows the command to continue.

In LDAPv2 environments, TLS is normally started using the LDAP Secure
URI scheme (ldaps://) instead of the normal LDAP URI scheme (ldap://).
 OpenLDAP command line tools allow either scheme to used with the -H
flag and with the URI ldap.conf(5) option.

16.2.2.1. TLS_CACERT <filename>
-------------------------------

This is equivalent to the server's TLSCACertificateFile option. As
noted in the TLS Configuration section, a client typically may need to
know about more CAs than a server, but otherwise the same
considerations apply.

16.2.2.2. TLS_CACERTDIR <path>
------------------------------

This is equivalent to the server's TLSCACertificatePath option. The
specified directory must be managed with the OpenSSL rehash command as
well.

16.2.2.3. TLS_CERT <filename>
-----------------------------

This directive specifies the file that contains the client
certificate. This is a user-only directive and can only be specified
in a user's .ldaprc file.

16.2.2.4. TLS_KEY <filename>
----------------------------

This directive specifies the file that contains the private key that
matches the certificate stored in the TLS_CERT file. The same
constraints mentioned for TLSCertificateKeyFile apply here. This is
also a user-only directive.

16.2.2.5. TLS_RANDFILE <filename>
---------------------------------

This directive is the same as the server's TLSRandFile option.

16.2.2.6. TLS_REQCERT { never | allow | try | demand }
------------------------------------------------------

This directive is equivalent to the server's TLSVerifyClient option.
However, for clients the default value is demand and there generally
is no good reason to change this setting.


17. Constructing a Distributed Directory Service
================================================

For many sites, running one or more slapd(8) that hold an entire
subtree of data is sufficient. But often it is desirable to have one
slapd refer to other directory services for a certain part of the tree
(which may or may not be running slapd).

slapd supports subordinate and superior knowledge information.
Subordinate knowledge information is held in referral objects
(RFC3296).

17.1. Subordinate Knowledge Information
---------------------------------------

Subordinate knowledge information may be provided to delegate a
subtree. Subordinate knowledge information is maintained in the
directory as a special referral object at the delegate point. The
referral object acts as a delegation point, gluing two services
together. This mechanism allows for hierarchical directory services to
be constructed.

A referral object has a structural object class of referral and has
the same Distinguished Name as the delegated subtree.  Generally, the
referral object will also provide the auxiliary object class
extensibleObject. This allows the entry to contain appropriate
Relative Distinguished Name values.  This is best demonstrated by
example.

If the server a.example.net holds dc=example,dc=net and wished to
delegate the subtree ou=subtree,dc=example,dc=net to another server
b.example.net, the following named referral object would be added to
a.example.net:

        dn: dc=subtree,dc=example,dc=net
        objectClass: referral
        objectClass: extensibleObject
        dc: subtree
        ref: ldap://b.example.net/dc=subtree,dc=example,dc=net

The server uses this information to generate referrals and search
continuations to subordinate servers.

For those familiar with X.500, a named referral object is similar to
an X.500 knowledge reference held in a subr DSE.

17.2. Superior Knowledge Information
------------------------------------

Superior knowledge information may be specified using the referral
directive.  The value is a list of URIs referring to superior
directory services.  For servers without immediate superiors, such as
for a.example.net in the example above, the server can be configured
to use a directory service with global knowledge, such as the OpenLDAP
Root Service (http://www.openldap.org/faq/index.cgi?file=393).

        referral        ldap://root.openldap.org/

However, as a.example.net is the immediate superior to b.example.net,
b.example.net would be configured as follows:

        referral        ldap://a.example.net/

The server uses this information to generate referrals for operations
acting upon entries not within or subordinate to any of the naming
contexts held by the server.

For those familiar with X.500, this use of the ref attribute is
similar to an X.500 knowledge reference held in a Supr DSE.

17.3. The ManageDsaIT Control
-----------------------------

Adding, modifying, and deleting referral objects is generally done
using ldapmodify(1) or similar tools which support the ManageDsaIT
control.  The ManageDsaIT control informs the server that you intend
to manage the referral object as a regular entry.  This keeps the
server from sending a referral result for requests which interrogate
or update referral objects.

The ManageDsaIT control should not be specified when managing regular
entries.

The -M option of ldapmodify(1) (and other tools) enables ManageDsaIT. 
For example:

        ldapmodify -M -f referral.ldif -x -D "cn=Manager,dc=example,dc=net" -W

or with ldapsearch(1):

        ldapsearch -M -b "dc=example,dc=net" -x "(objectclass=referral)" '*' ref

Note: the ref attribute is operational and must be explicitly
requested when desired in search results.

Note: the use of referrals to construct a Distributed Directory
Service is extremely clumsy and not well supported by common clients.
If an existing installation has already been built using referrals,
the use of the chain overlay to hide the referrals will greatly
improve the usability of the Directory system. A better approach would
be to use explicitly defined local and proxy databases in subordinate
configurations to provide a seamless view of the Distributed
Directory.

Note: LDAP operations, even subtree searches, normally access only one
database. That can be changed by gluing databases together with the
subordinate/olcSubordinate keyword. Please see slapd.conf(5) and
slapd-config(5).


18. Replication
===============

Replicated directories are a fundamental requirement for delivering a
resilient enterprise deployment.

OpenLDAP has various configuration options for creating a replicated
directory. In previous releases, replication was discussed in terms of
a master server and some number of slave servers. A master accepted
directory updates from other clients, and a slave only accepted
updates from a (single) master. The replication structure was rigidly
defined and any particular database could only fulfill a single role,
either master or slave. Another historic term introduced with OpenLDAP
2.4 was multimaster.

As OpenLDAP now supports a wide variety of replication topologies,
these terms have been deprecated in favor of provider/multi-provider
and consumer: A provider can accept external write operations and make
them available for retrieval by consumers; consumers request
replication updates from providers. Unlike the rigidly defined
master/slave relationships, provider/consumer roles are quite fluid:
replication updates received in a consumer can be further propagated
by that consumer to other servers, so a consumer can also act
simultaneously as a provider. Also, a consumer need not be an actual
LDAP server; it may be just an LDAP client.

The following sections will describe the replication technology and
discuss the various replication options that are available.

18.1. Replication Technology
----------------------------

18.1.1. LDAP Sync Replication
-----------------------------

The LDAP Sync Replication engine, syncrepl for short, is a
consumer-side replication engine that enables the consumer LDAP server
to maintain a shadow copy of a DIT fragment. A syncrepl engine resides
at the consumer and executes as one of the slapd(8) threads. It
creates and maintains a replica by connecting to the replication
provider to perform the initial DIT content load followed either by
periodic content polling or by timely updates upon content changes.

Syncrepl uses the LDAP Content Synchronization protocol (or LDAP Sync
for short) as the consumer synchronization protocol.  LDAP Sync
provides a stateful replication which supports both pull-based and
push-based synchronization and does not mandate the use of a history
store. In pull-based replication the consumer periodically polls the
provider for updates. In push-based replication the consumer listens
for updates that are sent by the provider in realtime. Since the
protocol does not require a history store, the provider does not need
to maintain any log of updates it has received (Note that the syncrepl
engine is extensible and additional replication protocols may be
supported in the future.).

Syncrepl keeps track of the status of the replication content by
maintaining and exchanging synchronization cookies. Because the
syncrepl consumer and provider maintain their content status, the
consumer can poll the provider content to perform incremental
synchronization by asking for the entries required to make the
consumer up-to-date with the provider content. Syncrepl also enables
convenient management of consumers by maintaining replication status. 
The consumer database can be constructed from a consumer-side or a
provider-side backup at any synchronization status. Syncrepl can
automatically resynchronize the consumer database to be up-to-date
with the current provider content.

Syncrepl supports both pull-based and push-based synchronization. In
its basic refreshOnly synchronization mode, the provider uses
pull-based synchronization where the consumer servers need not be
tracked and no history information is maintained.  The information
required for the provider to process periodic polling requests is
contained in the synchronization cookie of the request itself.  To
optimize the pull-based synchronization, syncrepl utilizes the present
phase of the LDAP Sync protocol as well as its delete phase, instead
of falling back on frequent full reloads. To further optimize the
pull-based synchronization, the provider can maintain a per-scope
session log as a history store. In its refreshAndPersist mode of
synchronization, the provider uses a push-based synchronization. The
provider keeps track of the consumer servers that have requested a
persistent search and sends them necessary updates as the provider
replication content gets modified.

With syncrepl, a consumer can create a replication agreement without
changing the provider's configurations and without restarting the
provider server, if the consumer server has appropriate access
privileges for the DIT fragment to be replicated. The consumer server
can stop the replication also without the need for provider-side
changes and restart.

Syncrepl supports both types of partial replication: sparse and
fractional The shadow DIT fragment is defined by a general search
criteria consisting of base, scope, filter, and attribute list.  The
consumer content is also subject to the access privileges of the bind
identity of the syncrepl replication connection.

Fractional replication uses explicit attribute lists to replicate only
a subset of the provider's attributes and sparse replication uses
base/scope/filter to replicate only a subset of the provider's
entries. Both cases are just refinements of the general search
criteria.

18.1.1.1. The LDAP Content Synchronization Protocol
---------------------------------------------------

The LDAP Sync protocol allows a client to maintain a synchronized copy
of a DIT fragment. The LDAP Sync operation is defined as a set of
controls and other protocol elements which extend the LDAP search
operation. This section introduces the LDAP Content Sync protocol only
briefly.  For more information, refer to RFC4533.

The LDAP Sync protocol supports both polling and listening for changes
by defining two respective synchronization operations: refreshOnly and
refreshAndPersist.  Polling is implemented by the refreshOnly
operation. The consumer polls the provider using an LDAP Search
request with an LDAP Sync control attached. The consumer copy is
synchronized to the provider copy at the time of polling using the
information returned in the search.  The provider finishes the search
operation by returning SearchResultDone at the end of the search
operation as in the normal search.  Listening is implemented by the
refreshAndPersist operation. As the name implies, it begins with a
search, like refreshOnly. Instead of finishing the search after
returning all entries currently matching the search criteria, the
synchronization search remains persistent in the provider. Subsequent
updates to the synchronization content in the provider cause
additional entry updates to be sent to the consumer.

The refreshOnly operation and the refresh stage of the
refreshAndPersist operation can be performed with a present phase or a
delete phase.

In the present phase, the provider sends the consumer the entries
updated within the search scope since the last synchronization. The
provider sends all requested attributes, be they changed or not, of
the updated entries.  For each unchanged entry which remains in the
scope, the provider sends a present message consisting only of the
name of the entry and the synchronization control representing state
present. The present message does not contain any attributes of the
entry. After the consumer receives all update and present entries, it
can reliably determine the new consumer copy by adding the entries
added to the provider, by replacing the entries modified at the
provider, and by deleting entries in the consumer copy which have not
been updated nor specified as being present at the provider.

The transmission of the updated entries in the delete phase is the
same as in the present phase. The provider sends all the requested
attributes of the entries updated within the search scope since the
last synchronization to the consumer. In the delete phase, however,
the provider sends a delete message for each entry deleted from the
search scope, instead of sending present messages.  The delete message
consists only of the name of the entry and the synchronization control
representing state delete.  The new consumer copy can be determined by
adding, modifying, and removing entries according to the
synchronization control attached to the SearchResultEntry message.

In the case that the LDAP Sync provider maintains a history store and
can determine which entries are scoped out of the consumer copy since
the last synchronization time, the provider can use the delete phase.
If the provider does not maintain any history store, cannot determine
the scoped-out entries from the history store, or the history store
does not cover the outdated synchronization state of the consumer, the
provider should use the present phase.  The use of the present phase
is much more efficient than a full content reload in terms of the
synchronization traffic.  To reduce the synchronization traffic
further, the LDAP Sync protocol also provides several optimizations
such as the transmission of the normalized entryUUIDs and the
transmission of multiple entryUUIDs in a single syncIdSet message.

At the end of the refreshOnly synchronization, the provider sends a
synchronization cookie to the consumer as a state indicator of the
consumer copy after the synchronization is completed.  The consumer
will present the received cookie when it requests the next incremental
synchronization to the provider.

When refreshAndPersist synchronization is used, the provider sends a
synchronization cookie at the end of the refresh stage by sending a
Sync Info message with refreshDone=TRUE.  It also sends a
synchronization cookie by attaching it to SearchResultEntry messages
generated in the persist stage of the synchronization search. During
the persist stage, the provider can also send a Sync Info message
containing the synchronization cookie at any time the provider wants
to update the consumer-side state indicator.

In the LDAP Sync protocol, entries are uniquely identified by the
entryUUID attribute value. It can function as a reliable identifier of
the entry. The DN of the entry, on the other hand, can be changed over
time and hence cannot be considered as the reliable identifier.  The
entryUUID is attached to each SearchResultEntry or
SearchResultReference as a part of the synchronization control.

18.1.1.2. Syncrepl Details
--------------------------

The syncrepl engine utilizes both the refreshOnly and the
refreshAndPersist operations of the LDAP Sync protocol.  If a syncrepl
specification is included in a database definition, slapd(8) launches
a syncrepl engine as a slapd(8) thread and schedules its execution. If
the refreshOnly operation is specified, the syncrepl engine will be
rescheduled at the interval time after a synchronization operation is
completed.  If the refreshAndPersist operation is specified, the
engine will remain active and process the persistent synchronization
messages from the provider.

The syncrepl engine utilizes both the present phase and the delete
phase of the refresh synchronization. It is possible to configure a
session log in the provider which stores the entryUUIDs of a finite
number of entries deleted from a database. Multiple consumers share
the same session log. The syncrepl engine uses the delete phase if the
session log is present and the state of the consumer server is recent
enough that no session log entries are truncated after the last
synchronization of the client.  The syncrepl engine uses the present
phase if no session log is configured for the replication content or
if the consumer is too outdated to be covered by the session log.  The
current design of the session log store is memory based, so the
information contained in the session log is not persistent over
multiple provider invocations. It is not currently supported to access
the session log store by using LDAP operations. It is also not
currently supported to impose access control to the session log.

As a further optimization, even in the case the synchronization search
is not associated with any session log, no entries will be transmitted
to the consumer server when there has been no update in the
replication context.

The syncrepl engine, which is a consumer-side replication engine, can
work with any backends. The LDAP Sync provider can be configured as an
overlay on any backend, but works best with the back-mdb backend.

The LDAP Sync provider maintains a contextCSN for each database as the
current synchronization state indicator of the provider content.  It
is the largest entryCSN in the provider context such that no
transactions for an entry having smaller entryCSN value remains
outstanding.  The contextCSN could not just be set to the largest
issued entryCSN because entryCSN is obtained before a transaction
starts and transactions are not committed in the issue order.

The provider stores the contextCSN of a context in the contextCSN
attribute of the context suffix entry. The attribute is not written to
the database after every update operation though; instead it is
maintained primarily in memory. At database start time the provider
reads the last saved contextCSN into memory and uses the in-memory
copy exclusively thereafter. By default, changes to the contextCSN as
a result of database updates will not be written to the database until
the server is cleanly shut down. A checkpoint facility exists to cause
the contextCSN to be written out more frequently if desired.

Note that at startup time, if the provider is unable to read a
contextCSN from the suffix entry, it will scan the entire database to
determine the value, and this scan may take quite a long time on a
large database. When a contextCSN value is read, the database will
still be scanned for any entryCSN values greater than it, to make sure
the contextCSN value truly reflects the greatest committed entryCSN in
the database. On databases which support inequality indexing, setting
an eq index on the entryCSN attribute and configuring contextCSN
checkpoints will greatly speed up this scanning step.

If no contextCSN can be determined by reading and scanning the
database, a new value will be generated. Also, if scanning the
database yielded a greater entryCSN than was previously recorded in
the suffix entry's contextCSN attribute, a checkpoint will be
immediately written with the new value.

The consumer also stores its replication state, which is the
provider's contextCSN received as a synchronization cookie, in the
contextCSN attribute of the suffix entry.  The replication state
maintained by a consumer server is used as the synchronization state
indicator when it performs subsequent incremental synchronization with
the provider server. It is also used as a provider-side
synchronization state indicator when it functions as a secondary
provider server in a cascading replication configuration.  Since the
consumer and provider state information are maintained in the same
location within their respective databases, any consumer can be
promoted to a provider (and vice versa) without any special actions.

Because a general search filter can be used in the syncrepl
specification, some entries in the context may be omitted from the
synchronization content.  The syncrepl engine creates a glue entry to
fill in the holes in the consumer context if any part of the consumer
content is subordinate to the holes. The glue entries will not be
returned in the search result unless ManageDsaIT control is provided.

Also as a consequence of the search filter used in the syncrepl
specification, it is possible for a modification to remove an entry
from the replication scope even though the entry has not been deleted
on the provider. Logically the entry must be deleted on the consumer
but in refreshOnly mode the provider cannot detect and propagate this
change without the use of the session log on the provider.

For configuration, please see the Syncrepl section.

18.2. Deployment Alternatives
-----------------------------

While the LDAP Sync specification only defines a narrow scope for
replication, the OpenLDAP implementation is extremely flexible and
supports a variety of operating modes to handle other scenarios not
explicitly addressed in the spec.

18.2.1. Delta-syncrepl replication
----------------------------------

o    Disadvantages of LDAP Sync replication:

LDAP Sync replication is an object-based replication mechanism. When
any attribute value in a replicated object is changed on the provider,
each consumer fetches and processes the complete changed object,
including both the changed and unchanged attribute values during
replication. One advantage of this approach is that when multiple
changes occur to a single object, the precise sequence of those
changes need not be preserved; only the final state of the entry is
significant. But this approach may have drawbacks when the usage
pattern involves single changes to multiple objects.

For example, suppose you have a database consisting of 102,400 objects
of 1 KB each. Further, suppose you routinely run a batch job to change
the value of a single two-byte attribute value that appears in each of
the 102,400 objects on the provider. Not counting LDAP and TCP/IP
protocol overhead, each time you run this job each consumer will
transfer and process 100 MB of data to process 200KB of changes!

99.98% of the data that is transmitted and processed in a case like
this will be redundant, since it represents values that did not
change. This is a waste of valuable transmission and processing
bandwidth and can cause an unacceptable replication backlog to
develop. While this situation is extreme, it serves to demonstrate a
very real problem that is encountered in some LDAP deployments.

o    Where Delta-syncrepl comes in:

Delta-syncrepl, a changelog-based variant of syncrepl, is designed to
address situations like the one described above. Delta-syncrepl works
by maintaining a changelog of a selectable depth in a separate
database on the provider. The replication consumer checks the
changelog for the changes it needs and, as long as the changelog
contains the needed changes, the consumer fetches the changes from the
changelog and applies them to its database. If, however, a consumer is
too far out of sync (or completely empty), conventional syncrepl is
used to bring it up to date and replication then switches back to the
delta-syncrepl mode.

Note: partial replication is incompatible with deltasync. For
deltasync to work, the replication user needs unrestricted read access
to both the main database and accesslog database.

Note: since the database state is stored in both the changelog DB and
the main DB on the provider, it is important to backup/restore both
the changelog DB and the main DB using slapcat/slapadd when restoring
a DB or copying it to another machine.

For configuration, please see the Delta-syncrepl section.

18.2.2. N-Way Multi-Provider Replication
----------------------------------------

Multi-Provider replication is a replication technique using Syncrepl
to replicate data to multiple provider ("Provider") Directory servers.

18.2.2.1. Valid Arguments for Multi-Provider replication
--------------------------------------------------------

o    If any provider fails, other providers will continue to accept
     updates

o    Avoids a single point of failure

o    Providers can be located in several physical sites i.e.
     distributed across the network/globe.

o    Good for Automatic failover/High Availability

18.2.2.2. Invalid Arguments for Multi-Provider replication
----------------------------------------------------------

(These are often claimed to be advantages of Multi-Provider
replication but those claims are false):

o    It has NOTHING to do with load balancing

o    Providers must propagate writes to all the other servers, which
     means the network traffic and write load spreads across all of
     the servers the same as for single-provider.

o    Server utilization and performance are at best identical for
     Multi-Provider and Single-Provider replication; at worst
     Single-Provider is superior because indexing can be tuned
     differently to optimize for the different usage patterns between
     the provider and the consumers.

18.2.2.3. Arguments against Multi-Provider replication
------------------------------------------------------

o    Breaks the data consistency guarantees of the directory model

o    http://www.openldap.org/faq/data/cache/1240.html

o    If connectivity with a provider is lost because of a network
     partition, then "automatic failover" can just compound the
     problem

o    Typically, a particular machine cannot distinguish between losing
     contact with a peer because that peer crashed, or because the
     network link has failed

o    If a network is partitioned and multiple clients start writing to
     each of the "providers" then reconciliation will be a pain; it
     may be best to simply deny writes to the clients that are
     partitioned from the single provider

For configuration, please see the N-Way Multi-Provider section below

18.2.3. Mirror mode replication
-------------------------------

Mirror mode is a hybrid configuration that provides all of the
consistency guarantees of single-provider replication, while also
providing the high availability of multi-provider. In Mirror mode two
providers are set up to replicate from each other (as a multi-provider
configuration), but an external frontend is employed to direct all
writes to only one of the two servers. The second provider will only
be used for writes if the first provider crashes, at which point the
frontend will switch to directing all writes to the second provider.
When a crashed provider is repaired and restarted it will
automatically catch up to any changes on the running provider and
resync.

18.2.3.1. Arguments for Mirror mode
-----------------------------------

o    Provides a high-availability (HA) solution for directory writes
     (replicas handle reads)

o    As long as one provider is operational, writes can safely be
     accepted

o    Provider nodes replicate from each other, so they are always up
     to date and can be ready to take over (hot standby)

o    Syncrepl also allows the provider nodes to re-synchronize after
     any downtime

18.2.3.2. Arguments against Mirror mode
---------------------------------------

o    Mirror mode is not what is termed as a Multi-Provider solution.
     This is because writes have to go to just one of the mirror nodes
     at a time

o    Mirror mode can be termed as Active-Active Hot-Standby, therefore
     an external server (slapd in proxy mode) or device (hardware load
     balancer) is needed to manage which provider is currently active

o    Backups are managed slightly differently

For configuration, please see the Mirror mode section below

18.2.4. Syncrepl Proxy Mode
---------------------------

While the LDAP Sync protocol supports both pull- and push-based
replication, the push mode (refreshAndPersist) must still be initiated
from the consumer before the provider can begin pushing changes. In
some network configurations, particularly where firewalls restrict the
direction in which connections can be made, a provider-initiated push
mode may be needed.

This mode can be configured with the aid of the LDAP Backend (Backends
and slapd-ldap(8)). Instead of running the syncrepl engine on the
actual consumer, a slapd-ldap proxy is set up near (or collocated
with) the provider that points to the consumer, and the syncrepl
engine runs on the proxy.

For configuration, please see the Syncrepl Proxy section.

18.3. Configuring the different replication types
-------------------------------------------------

18.3.1. Syncrepl
----------------

18.3.1.1. Syncrepl configuration
--------------------------------

Because syncrepl is a consumer-side replication engine, the syncrepl
specification is defined in slapd.conf(5) of the consumer server, not
in the provider server's configuration file.  The initial loading of
the consumer content can be performed either by starting the syncrepl
engine with no synchronization cookie or by populating the consumer by
loading an LDIF file dumped as a backup at the provider.

When loading from a backup, it is not required to perform the initial
loading from the up-to-date backup of the provider content. The
syncrepl engine will automatically synchronize the initial consumer to
the current provider content. As a result, it is not required to stop
the provider server in order to avoid the replication inconsistency
caused by the updates to the provider content during the content
backup and loading process.

When replicating a large scale directory, especially in a bandwidth
constrained environment, it is advised to load the consumer from a
backup instead of performing a full initial load using syncrepl.

18.3.1.2. Set up the provider slapd
-----------------------------------

The provider is implemented as an overlay, so the overlay itself must
first be configured in slapd.conf(5) before it can be used. The
provider has two primary configuration directives and two secondary
directives for when delta-syncrepl is being used.

Because the LDAP Sync search is subject to access control, proper
access control privileges should be set up for the replicated content.
In many environments the replicas are meant to carry the same data as
provider so the replication user needs unrestricted read access to the
database and as such this tends to be the first access rule for that
database:

 access to * by "$REPLICATOR" read by * break

However if partial replication is desired, the access rules can be
tightened appropriately.

The two primary options to configure are the checkpoint and sessionlog
behaviors.

The contextCSN checkpoint is configured by the

        syncprov-checkpoint <ops> <minutes>

directive. Checkpoints are only tested after successful write
operations. If <ops> operations or more than <minutes> time has passed
since the last checkpoint, a new checkpoint is performed.
Checkpointing is disabled by default.

If an accesslog is maintained for this database and contains all the
successful writes, it is the preferred way to provide the resync
information:

 syncprov-sessionlog-source <accesslog db suffix>

Otherwise an in memory session session log is configured by the

        syncprov-sessionlog <ops>

directive, where <ops> is the maximum number of session log entries
the session log can record. All write operations (except Adds) are
recorded in the log.

Note that using the session log requires searching on the entryUUID
attribute. Setting an eq index on this attribute will greatly benefit
the performance of the session log on the provider.

The reloadhint option is configured by the

        syncprov-reloadhint <TRUE|FALSE>

directive. It must be set TRUE when using the accesslog overlay for
delta-based syncrepl replication support. The default is FALSE.

The nonpresent option is configured by the

        syncprov-nopresent <TRUE|FALSE>

directive. This value should only be set TRUE for a syncprov instance
on top of a log database (such as one managed by the accesslog
overlay). The default is FALSE.

A more complete example of the slapd.conf(5) content is thus:

        database mdb
        maxsize 1073741824
        suffix dc=Example,dc=com
        rootdn dc=Example,dc=com
        directory /var/ldap/db
        index objectclass,entryCSN,entryUUID eq

        overlay syncprov
        syncprov-checkpoint 100 10
        syncprov-sessionlog-source cn=accesslog

18.3.1.3. Set up the consumer slapd
-----------------------------------

The syncrepl directive is specified in the database section of
slapd.conf(5) for the consumer context. The syncrepl engine is backend
independent and the directive can be defined with any database type.

        database mdb
        maxsize 1073741824
        suffix dc=Example,dc=com
        rootdn dc=Example,dc=com
        directory /var/ldap/db
        index objectclass,entryCSN,entryUUID eq

        syncrepl rid=123
                provider=ldap://provider.example.com:389
                type=refreshOnly
                interval=01:00:00:00
                searchbase="dc=example,dc=com"
                filter="(objectClass=organizationalPerson)"
                scope=sub
                attrs="cn,sn,ou,telephoneNumber,title,l"
                schemachecking=off
                bindmethod=simple
                binddn="cn=syncuser,dc=example,dc=com"
                credentials=secret

In this example, the consumer will connect to the provider slapd(8) at
port 389 of ldap://provider.example.com to perform a polling
(refreshOnly) mode of synchronization once a day.  It will bind as
cn=syncuser,dc=example,dc=com using simple authentication with
password "secret".  Note that the access control privilege of
cn=syncuser,dc=example,dc=com should be set appropriately in the
provider to retrieve the desired replication content. Also the search
limits must be high enough on the provider to allow the syncuser to
retrieve a complete copy of the requested content.  The consumer uses
the rootdn to write to its database so it always has full permissions
to write all content.

The synchronization search in the above example will search for the
entries whose objectClass is organizationalPerson in the entire
subtree rooted at dc=example,dc=com. The requested attributes are cn,
sn, ou, telephoneNumber, title, and l. The schema checking is turned
off, so that the consumer slapd(8) will not enforce entry schema
checking when it processes updates from the provider slapd(8).

For more detailed information on the syncrepl directive, see the
syncrepl section of The slapd Configuration File chapter of this admin
guide.

18.3.1.4. Start the provider and the consumer slapd
---------------------------------------------------

The provider slapd(8) is not required to be restarted. contextCSN is
automatically generated as needed: it might be originally contained in
the LDIF file, generated by slapadd (8), generated upon changes in the
context, or generated when the first LDAP Sync search arrives at the
provider.  If an LDIF file is being loaded which did not previously
contain the contextCSN, the -w option should be used with slapadd (8)
to cause it to be generated. This will allow the server to startup a
little quicker the first time it runs.

When starting a consumer slapd(8), it is possible to provide a
synchronization cookie as the -c cookie command line option in order
to start the synchronization from a specific state.  The cookie is a
comma separated list of name=value pairs. Currently supported syncrepl
cookie fields are csn=<csn> and rid=<rid>. <csn> represents the
current synchronization state of the consumer. <rid> identifies a
consumer locally within the consumer server. It is used to relate the
cookie to the syncrepl definition in slapd.conf(5) which has the
matching <rid>.  The <rid> must have no more than 3 decimal digits. 
The command line cookie overrides the synchronization cookie stored in
the consumer database.

18.3.2. Delta-syncrepl
----------------------

18.3.2.1. Delta-syncrepl Provider configuration
-----------------------------------------------

Setting up delta-syncrepl requires configuration changes on both the
provider and replica servers:

     # Give the replicator DN unlimited read access.  This ACL needs to be
     # merged with other ACL statements, and/or moved within the scope
     # of a database.  The "by * break" portion causes evaluation of
     # subsequent rules.  See slapd.access(5) for details.
     access to *
        by dn.base="cn=replicator,dc=example,dc=com" read
        by * break

     # Set the module path location
     modulepath /opt/symas/lib/openldap

     # Load the mdb backend
     moduleload back_mdb.la

     # Load the accesslog overlay
     moduleload accesslog.la

     #Load the syncprov overlay
     moduleload syncprov.la

     # Accesslog database definitions
     database mdb
     suffix cn=accesslog
     directory /db/accesslog
     rootdn cn=accesslog
     index default eq
     index entryCSN,objectClass,reqEnd,reqResult,reqStart,reqDN

     overlay syncprov
     syncprov-nopresent TRUE
     syncprov-reloadhint TRUE

     # Let the replicator DN have limitless searches
     limits dn.exact="cn=replicator,dc=example,dc=com" time.soft=unlimited time.hard=unlimited size.soft=unlimited size.hard=unlimited

     # Primary database definitions
     database mdb
     suffix "dc=symas,dc=com"
     rootdn "cn=manager,dc=symas,dc=com"

     ## Whatever other configuration options are desired

     # syncprov specific indexing
     index entryCSN eq
     index entryUUID eq

     # syncrepl Provider for primary db
     overlay syncprov
     syncprov-checkpoint 1000 60

     # accesslog overlay definitions for primary db
     overlay accesslog
     logdb cn=accesslog
     logops writes
     logsuccess TRUE
     # scan the accesslog DB every day, and purge entries older than 7 days
     logpurge 07+00:00 01+00:00

     # Let the replicator DN have limitless searches
     limits dn.exact="cn=replicator,dc=example,dc=com" time.soft=unlimited time.hard=unlimited size.soft=unlimited size.hard=unlimited

For more information, always consult the relevant man pages
(slapo-accesslog(5) and slapd.conf(5))

18.3.2.2. Delta-syncrepl Consumer configuration
-----------------------------------------------

     # Replica database configuration
     database mdb
     suffix "dc=symas,dc=com"
     rootdn "cn=manager,dc=symas,dc=com"

     ## Whatever other configuration bits for the replica, like indexing
     ## that you want

     # syncrepl specific indices
     index entryUUID eq

     # syncrepl directives
     syncrepl  rid=0
               provider=ldap://ldapprovider.example.com:389
               bindmethod=simple
               binddn="cn=replicator,dc=example,dc=com"
               credentials=secret
               searchbase="dc=example,dc=com"
               logbase="cn=accesslog"
               logfilter="(&(objectClass=auditWriteObject)(reqResult=0))"
               schemachecking=on
               type=refreshAndPersist
               retry="60 +"
               syncdata=accesslog

     # Refer updates to the provider
     updateref               ldap://ldapprovider.example.com

The above configuration assumes that you have a replicator identity
defined in your database that can be used to bind to the provider.

Note: An accesslog database is unique to a given provider. It should
never be replicated.

18.3.3. N-Way Multi-Provider
----------------------------

For the following example we will be using 3 Provider nodes. Keeping
in line with test050-syncrepl-multiprovider of the OpenLDAP test
suite, we will be configuring slapd(8) via cn=config

This sets up the config database:

     dn: cn=config
     objectClass: olcGlobal
     cn: config
     olcServerID: 1

     dn: olcDatabase={0}config,cn=config
     objectClass: olcDatabaseConfig
     olcDatabase: {0}config
     olcRootPW: secret

Each server must have a unique server ID (SID), so second and third
servers will have a different olcServerID obviously:

     dn: cn=config
     objectClass: olcGlobal
     cn: config
     olcServerID: 2

     dn: olcDatabase={0}config,cn=config
     objectClass: olcDatabaseConfig
     olcDatabase: {0}config
     olcRootPW: secret

This sets up syncrepl as a provider (since these are all providers):

     dn: cn=module,cn=config
     objectClass: olcModuleList
     cn: module
     olcModulePath: /usr/local/libexec/openldap
     olcModuleLoad: syncprov.la

Now we setup the first Provider Node (replace $URI1, $URI2 and $URI3
etc. with your actual ldap urls):

     dn: cn=config
     changetype: modify
     replace: olcServerID
     olcServerID: 1 $URI1
     olcServerID: 2 $URI2
     olcServerID: 3 $URI3

     dn: olcOverlay=syncprov,olcDatabase={0}config,cn=config
     changetype: add
     objectClass: olcOverlayConfig
     objectClass: olcSyncProvConfig
     olcOverlay: syncprov

     dn: olcDatabase={0}config,cn=config
     changetype: modify
     add: olcSyncRepl
     olcSyncRepl: rid=001 provider=$URI1 binddn="cn=config" bindmethod=simple
       credentials=secret searchbase="cn=config" type=refreshAndPersist
       retry="5 5 300 5" timeout=1
     olcSyncRepl: rid=002 provider=$URI2 binddn="cn=config" bindmethod=simple
       credentials=secret searchbase="cn=config" type=refreshAndPersist
       retry="5 5 300 5" timeout=1
     olcSyncRepl: rid=003 provider=$URI3 binddn="cn=config" bindmethod=simple
       credentials=secret searchbase="cn=config" type=refreshAndPersist
       retry="5 5 300 5" timeout=1
     -
     add: olcMultiProvider
     olcMultiProvider: TRUE

Now start up the provider and a consumer/s, also add the above LDIF to
the first consumer, second consumer etc. It will then replicate
cn=config. You now have N-Way Multi-Provider on the config database.

We still have to replicate the actual data, not just the config, so
add to the provider (all active and configured consumers/providers
will pull down this config, as they are all syncing). Also, replace
all ${} variables with whatever is applicable to your setup:

     dn: olcDatabase={1}$BACKEND,cn=config
     objectClass: olcDatabaseConfig
     objectClass: olc${BACKEND}Config
     olcDatabase: {1}$BACKEND
     olcSuffix: $BASEDN
     olcDbDirectory: ./db
     olcRootDN: $MANAGERDN
     olcRootPW: $PASSWD
     olcLimits: dn.exact="$MANAGERDN" time.soft=unlimited time.hard=unlimited
       size.soft=unlimited size.hard=unlimited
     olcSyncRepl: rid=004 provider=$URI1 binddn="$MANAGERDN" bindmethod=simple
       credentials=$PASSWD searchbase="$BASEDN" type=refreshOnly
       interval=00:00:00:10 retry="5 5 300 5" timeout=1
     olcSyncRepl: rid=005 provider=$URI2 binddn="$MANAGERDN" bindmethod=simple
       credentials=$PASSWD searchbase="$BASEDN" type=refreshOnly
       interval=00:00:00:10 retry="5 5 300 5" timeout=1
     olcSyncRepl: rid=006 provider=$URI3 binddn="$MANAGERDN" bindmethod=simple
       credentials=$PASSWD searchbase="$BASEDN" type=refreshOnly
       interval=00:00:00:10 retry="5 5 300 5" timeout=1
     olcMultiProvider: TRUE

     dn: olcOverlay=syncprov,olcDatabase={1}${BACKEND},cn=config
     changetype: add
     objectClass: olcOverlayConfig
     objectClass: olcSyncProvConfig
     olcOverlay: syncprov

Note: All of your servers' clocks must be tightly synchronized using
e.g. NTP http://www.ntp.org/, atomic clock, or some other reliable
time reference.

Note: As stated in slapd-config(5), URLs specified in olcSyncRepl
directives are the URLs of the servers from which to replicate. These
must exactly match the URLs slapd listens on (-h in Command-Line
Options). Otherwise slapd may attempt to replicate from itself,
causing a loop.

Note: The entryCSN and contextCSN attributes are used to track changes
to an entry and naming context, respectively. The SID which must be
unique for each replication provider is a component of these CSNs. If
you're using slapadd to load a database and there are no entryCSNs
already present in the input LDIF, slapadd will generate them with a
SID of 000. This is not a valid SID for multi-provider replication,
and you should use the -S option of slapadd (8) to specify a valid SID
for these generated CSNs. If there are existing entryCSNs in the input
LDIF, slapadd will not change them.

18.3.4. Mirror mode
-------------------

Mirror mode configuration is actually very easy. If you have ever
setup a normal slapd syncrepl provider, then the only change is the
following two directives:

       multiprovider  on
       serverID    1

Note: You need to make sure that the serverID of each provider node is
different and add it as a global configuration option.

18.3.4.1. Mirror Node Configuration
-----------------------------------

The first step is to configure the syncrepl provider the same as in
the Set up the provider slapd section.

Here's a specific cut down example using LDAP Sync Replication in
refreshAndPersist mode:

Mirror mode node 1:

       # Global section
       serverID    1
       # database section

       # syncrepl directive
       syncrepl      rid=001
                     provider=ldap://ldap-sid2.example.com
                     bindmethod=simple
                     binddn="cn=mirrormode,dc=example,dc=com"
                     credentials=mirrormode
                     searchbase="dc=example,dc=com"
                     schemachecking=on
                     type=refreshAndPersist
                     retry="60 +"

       multiprovider on

Mirror mode node 2:

       # Global section
       serverID    2
       # database section

       # syncrepl directive
       syncrepl      rid=001
                     provider=ldap://ldap-sid1.example.com
                     bindmethod=simple
                     binddn="cn=mirrormode,dc=example,dc=com"
                     credentials=mirrormode
                     searchbase="dc=example,dc=com"
                     schemachecking=on
                     type=refreshAndPersist
                     retry="60 +"

       multiprovider on

It's simple really; each Mirror mode node is setup exactly the same,
except that the serverID is unique, and each consumer is pointed to
the other server.

18.3.4.1.1. Failover Configuration
----------------------------------

There are generally 2 choices for this; 1.  Hardware
proxies/load-balancing or dedicated proxy software, 2. using a
Back-LDAP proxy as a syncrepl provider

A typical enterprise example might be:

** Unable to import figure dual_dc.png **

Figure X.Y: Mirror mode in a Dual Data Center Configuration

18.3.4.1.2. Normal Consumer Configuration
-----------------------------------------

This is exactly the same as the Set up the consumer slapd section. It
can either setup in normal syncrepl replication mode, or in
delta-syncrepl replication mode.

18.3.4.2. Mirror mode Summary
-----------------------------

You will now have a directory architecture that provides all of the
consistency guarantees of single-provider replication, while also
providing the high availability of multi-provider replication.

18.3.5. Syncrepl Proxy
----------------------

** Unable to import figure push-based-complete.png **

Figure X.Y: Replacing slurpd

The following example is for a self-contained push-based replication
solution:

        #######################################################################
        # Standard OpenLDAP Provider
        #######################################################################

        include     /usr/local/etc/openldap/schema/core.schema
        include     /usr/local/etc/openldap/schema/cosine.schema
        include     /usr/local/etc/openldap/schema/nis.schema
        include     /usr/local/etc/openldap/schema/inetorgperson.schema

        include     /usr/local/etc/openldap/slapd.acl

        modulepath  /usr/local/libexec/openldap
        moduleload  back_mdb.la
        moduleload  syncprov.la
        moduleload  back_ldap.la

        pidfile     /usr/local/var/slapd.pid
        argsfile    /usr/local/var/slapd.args

        loglevel    sync stats

        database    mdb
        suffix      "dc=suretecsystems,dc=com"
        directory   /usr/local/var/openldap-data

        checkpoint      1024 5

        index       objectClass eq
        # rest of indexes
        index       default     sub

        rootdn          "cn=admin,dc=suretecsystems,dc=com"
        rootpw          testing

        # syncprov specific indexing
        index entryCSN eq
        index entryUUID eq

        # syncrepl Provider for primary db
        overlay syncprov
        syncprov-checkpoint 1000 60

        # Let the replicator DN have limitless searches
        limits dn.exact="cn=replicator,dc=suretecsystems,dc=com" time.soft=unlimited time.hard=unlimited size.soft=unlimited size.hard=unlimited

        database    monitor

        database    config
        rootpw          testing

        ##############################################################################
        # Consumer Proxy that pulls in data via Syncrepl and pushes out via slapd-ldap
        ##############################################################################

        database        ldap
        # ignore conflicts with other databases, as we need to push out to same suffix
        hidden              on
        suffix          "dc=suretecsystems,dc=com"
        rootdn          "cn=slapd-ldap"
        uri             ldap://localhost:9012/

        lastmod         on

        # We don't need any access to this DSA
        restrict        all

        acl-bind        bindmethod=simple
                        binddn="cn=replicator,dc=suretecsystems,dc=com"
                        credentials=testing

        syncrepl        rid=001
                        provider=ldap://localhost:9011/
                        binddn="cn=replicator,dc=suretecsystems,dc=com"
                        bindmethod=simple
                        credentials=testing
                        searchbase="dc=suretecsystems,dc=com"
                        type=refreshAndPersist
                        retry="5 5 300 5"

        overlay         syncprov

A replica configuration for this type of setup could be:

        #######################################################################
        # Standard OpenLDAP Replica without Syncrepl
        #######################################################################

        include     /usr/local/etc/openldap/schema/core.schema
        include     /usr/local/etc/openldap/schema/cosine.schema
        include     /usr/local/etc/openldap/schema/nis.schema
        include     /usr/local/etc/openldap/schema/inetorgperson.schema

        include     /usr/local/etc/openldap/slapd.acl

        modulepath  /usr/local/libexec/openldap
        moduleload  back_mdb.la
        moduleload  syncprov.la
        moduleload  back_ldap.la

        pidfile     /usr/local/var/slapd.pid
        argsfile    /usr/local/var/slapd.args

        loglevel    sync stats

        database    mdb
        suffix      "dc=suretecsystems,dc=com"
        directory   /usr/local/var/openldap-consumer/data

        maxsize         85899345920
        checkpoint      1024 5

        index       objectClass eq
        # rest of indexes
        index       default     sub

        rootdn          "cn=admin,dc=suretecsystems,dc=com"
        rootpw          testing

        # Let the replicator DN have limitless searches
        limits dn.exact="cn=replicator,dc=suretecsystems,dc=com" time.soft=unlimited time.hard=unlimited size.soft=unlimited size.hard=unlimited

        updatedn "cn=replicator,dc=suretecsystems,dc=com"

        # Refer updates to the provider
        updateref   ldap://localhost:9011

        database    monitor

        database    config
        rootpw          testing

You can see we use the updatedn directive here and example ACLs
(usr/local/etc/openldap/slapd.acl) for this could be:

        # Give the replicator DN unlimited read access.  This ACL may need to be
        # merged with other ACL statements.

        access to *
             by dn.base="cn=replicator,dc=suretecsystems,dc=com" write
             by * break

        access to dn.base=""
                by * read

        access to dn.base="cn=Subschema"
                by * read

        access to dn.subtree="cn=Monitor"
            by dn.exact="uid=admin,dc=suretecsystems,dc=com" write
            by users read
            by * none

        access to *
                by self write
                by * read

In order to support more replicas, just add more database ldap
sections and increment the syncrepl rid number accordingly.

Note: You must populate the Provider and Replica directories with the
same data, unlike when using normal Syncrepl

If you do not have access to modify the provider directory
configuration you can configure a standalone ldap proxy, which might
look like:

** Unable to import figure push-based-standalone.png **

Figure X.Y: Replacing slurpd with a standalone version

The following configuration is an example of a standalone LDAP Proxy:

        include     /usr/local/etc/openldap/schema/core.schema
        include     /usr/local/etc/openldap/schema/cosine.schema
        include     /usr/local/etc/openldap/schema/nis.schema
        include     /usr/local/etc/openldap/schema/inetorgperson.schema

        include     /usr/local/etc/openldap/slapd.acl

        modulepath  /usr/local/libexec/openldap
        moduleload  syncprov.la
        moduleload  back_ldap.la

        ##############################################################################
        # Consumer Proxy that pulls in data via Syncrepl and pushes out via slapd-ldap
        ##############################################################################

        database        ldap
        # ignore conflicts with other databases, as we need to push out to same suffix
        hidden              on
        suffix          "dc=suretecsystems,dc=com"
        rootdn          "cn=slapd-ldap"
        uri             ldap://localhost:9012/

        lastmod         on

        # We don't need any access to this DSA
        restrict        all

        acl-bind        bindmethod=simple
                        binddn="cn=replicator,dc=suretecsystems,dc=com"
                        credentials=testing

        syncrepl        rid=001
                        provider=ldap://localhost:9011/
                        binddn="cn=replicator,dc=suretecsystems,dc=com"
                        bindmethod=simple
                        credentials=testing
                        searchbase="dc=suretecsystems,dc=com"
                        type=refreshAndPersist
                        retry="5 5 300 5"

        overlay         syncprov

As you can see, you can let your imagination go wild using Syncrepl
and slapd-ldap(8) tailoring your replication to fit your specific
network topology.


19. Maintenance
===============

System Administration is all about maintenance, so it is only fair
that we discuss how to correctly maintain an OpenLDAP deployment.

19.1. Directory Backups
-----------------------

Backup strategies largely depend on the amount of change in the
database and how much of that change an administrator might be willing
to lose in a catastrophic failure. There are two basic methods that
can be used:

1. Backup the LMDB database itself

The LMDB database can be copied live using the mdb_copy command.  If
the database is a sparse file via the use of the "writemap"
environment flag, the resulting copy will be the actual size of the
database rather than a sparse copy.

2. Periodically run slapcat and back up the LDIF file:

Slapcat can be run while slapd is active. However, one runs the risk
of an inconsistent database- not from the point of slapd, but from the
point of the applications using LDAP. For example, if a provisioning
application performed tasks that consisted of several LDAP operations,
and the slapcat took place concurrently with those operations, then
there might be inconsistencies in the LDAP database from the point of
view of that provisioning application and applications that depended
on it. One must, therefore, be convinced something like that won't
happen. One way to do that would be to put the database in read-only
mode while performing the slapcat. The other disadvantage of this
approach is that the generated LDIF files can be rather large and the
accumulation of the day's backups could add up to a substantial amount
of space.

You can use slapcat(8) to generate an LDIF file for each of your
slapd(8) back-mdb databases.

    slapcat -f slapd.conf -b "dc=example,dc=com"

For back-mdb this command may be ran while slapd(8) is running.

19.2. Checkpointing
-------------------

Setting a checkpoint is only necessary when back-mdb has the dbnosync
flag set. Otherwise it has no effect. With back-mdb the kbyte option
is not implemented, meaning it will only run a checkpoint based on the
elapsed amount of minutes flag.

19.3. Migration
---------------

If upgrading, please consult Upgrading from 2.5.x first to see if you
need to make changes to your configuration as part of the upgrade.

After that, the simplest steps needed to migrate between versions or
upgrade, depending on your deployment type are:



1.   Stop the current server when convenient



2.   slapcat the current data out



3.   Clear out the current data directory
     (/usr/local/var/openldap-data/)



4.   Perform the software upgrades



5.   Perform any configuration upgrades required



6.   slapadd the exported data back into the directory



7.   Start the server

Obviously this doesn't cater for any complicated deployments with
N-Way Multi-Provider, but following the above sections and using
either commercial support or community support should help. Also check
the Troubleshooting section.


20. Monitoring
==============

slapd(8) supports an optional LDAP monitoring interface you can use to
obtain information regarding the current state of your slapd instance.
 For instance, the interface allows you to determine how many clients
are connected to the server currently. The monitoring information is
provided by a specialized backend, the monitor backend.  A manual
page, slapd-monitor(5) is available.

When the monitoring interface is enabled, LDAP clients may be used to
access information provided by the monitor backend, subject to access
and other controls.

When enabled, the monitor backend dynamically generates and returns
objects in response to search requests in the cn=Monitor subtree. 
Each object contains information about a particular aspect of the
server.  The information is held in a combination of user applications
and operational attributes.   This information can be accessed with
ldapsearch(1), with any general-purpose LDAP browser, or with
specialized monitoring tools.  The Accessing Monitoring Information
section provides a brief tutorial on how to use ldapsearch(1) to
access monitoring information, while the Monitor information section
details monitoring information base and its organization.

While support for the monitor backend is included in default builds of
slapd(8), this support requires some configuration to become active. 
This may be done using either cn=config or slapd.conf(5).  The former
is discussed in the Monitor configuration via cn=config section of
this of this chapter.  The latter is discussed in the Monitor
configuration via slapd.conf(5) section of this chapter.  These
sections assume monitor backend is built into slapd (e.g.,
--enable-monitor=yes, the default).  If the monitor backend was built
as a module (e.g., --enable-monitor=mod, this module must loaded. 
Loading of modules is discussed in the Configuring slapd and The slapd
Configuration File chapters.

20.1. Monitor configuration via cn=config(5)
--------------------------------------------

The monitor backend is statically built into slapd and can be
instantiated via ldapadd.

 dn: olcDatabase=monitor,cn=config
 objectClass: olcDatabaseConfig
 olcDatabase: monitor

20.2. Monitor configuration via slapd.conf(5)
---------------------------------------------

Configuration of the slapd.conf(5) to support LDAP monitoring is quite
simple.

First, ensure core.schema schema configuration file is included by
your slapd.conf(5) file.  The monitor backend requires it.

Second, instantiate the monitor backend by adding a database monitor
directive below your existing database sections.  For instance:

        database monitor

Lastly, add additional global or database directives as needed.

Like most other database backends, the monitor backend does honor
slapd(8) access and other administrative controls.   As some monitor
information may be sensitive, it is generally recommend access to
cn=monitor be restricted to directory administrators and their
monitoring agents.  Adding an access directive immediately below the
database monitor directive is a clear and effective approach for
controlling access.  For instance, the addition of the following
access directive immediately below the database monitor directive
restricts access to monitoring information to the specified directory
manager.

        access to *
                by dn.exact="cn=Manager,dc=example,dc=com
                by * none

More information on slapd(8) access controls, see The access Control
Directive section of the The slapd Configuration File chapter and
slapd.access(5).

After restarting slapd(8), you are ready to start exploring the
monitoring information provided in cn=config as discussed in the
Accessing Monitoring Information section of this chapter.

One can verify slapd(8) is properly configured to provide monitoring
information by attempting to read the cn=monitor object. For instance,
if the following ldapsearch(1) command returns the cn=monitor object
(with, as requested, no attributes), it's working.

        ldapsearch -x -D 'cn=Manager,dc=example,dc=com' -W \
                -b 'cn=Monitor' -s base 1.1

Note that unlike general purpose database backends, the database
suffix is hardcoded.  It's always cn=Monitor.  So no suffix directive
should be provided.  Also note that general purpose database backends,
the monitor backend cannot be instantiated multiple times.  That is,
there can only be one (or zero) occurrences of database monitor in the
server's configuration.

20.3. Accessing Monitoring Information
--------------------------------------

As previously discussed, when enabled, the monitor backend dynamically
generates and returns objects in response to search requests in the
cn=Monitor subtree.  Each object contains information about a
particular aspect of the server.  The information is held in a
combination of user applications and operational attributes.  This
information can be accessed with ldapsearch(1), with any
general-purpose LDAP browser, or with specialized monitoring tools.

This section provides a provides a brief tutorial on how to use
ldapsearch(1) to access monitoring information.

To inspect any particular monitor object, one performs search
operation on the object with a baseObject scope and a (objectClass=*)
filter.  As the monitoring information is contained in a combination
of user applications and operational attributes, the return all user
applications attributes (e.g., '*') and all operational attributes
(e.g., '+') should be requested.   For instance, to read the
cn=Monitor object itself, the ldapsearch(1) command (modified to fit
your configuration) can be used:

        ldapsearch -x -D 'cn=Manager,dc=example,dc=com' -W \
                -b 'cn=Monitor' -s base '(objectClass=*)' '*' '+'

When run against your server, this should produce output similar to:

        dn: cn=Monitor
        objectClass: monitorServer
        structuralObjectClass: monitorServer
        cn: Monitor
        creatorsName:
        modifiersName:
        createTimestamp: 20061208223558Z
        modifyTimestamp: 20061208223558Z
        description: This subtree contains monitoring/managing objects.
        description: This object contains information about this server.
        description: Most of the information is held in operational attributes, which
         must be explicitly requested.
        monitoredInfo: OpenLDAP: slapd 2.5 (Dec  7 2006 17:30:29)
        entryDN: cn=Monitor
        subschemaSubentry: cn=Subschema
        hasSubordinates: TRUE

To reduce the number of uninteresting attributes returned, one can be
more selective when requesting which attributes are to be returned. 
For instance, one could request the return of all attributes allowed
by the monitorServer object class (e.g., @objectClass) instead of all
user and all operational attributes:

        ldapsearch -x -D 'cn=Manager,dc=example,dc=com' -W \
                -b 'cn=Monitor' -s base '(objectClass=*)' '@monitorServer'

This limits the output as follows:

        dn: cn=Monitor
        objectClass: monitorServer
        cn: Monitor
        description: This subtree contains monitoring/managing objects.
        description: This object contains information about this server.
        description: Most of the information is held in operational attributes, which
         must be explicitly requested.
        monitoredInfo: OpenLDAP: slapd 2.X (Dec  7 2006 17:30:29)

To return the names of all the monitoring objects, one performs a
search of cn=Monitor with subtree scope and (objectClass=*) filter and
requesting no attributes (e.g., 1.1) be returned.

        ldapsearch -x -D 'cn=Manager,dc=example,dc=com' -W -b 'cn=Monitor' -s sub 1.1

If you run this command you will discover that there are many objects
in the cn=Monitor subtree.  The following section describes some of
the commonly available monitoring objects.

20.4. Monitor Information
-------------------------

The monitor backend provides a wealth of information useful for
monitoring the slapd(8) contained in set of monitor objects. Each
object contains information about a particular aspect of the server,
such as a backends, a connection, or a thread. Some objects serve as
containers for other objects and used to construct a hierarchy of
objects.

In this hierarchy, the most superior object is {cn=Monitor}. While
this object primarily serves as a container for other objects, most of
which are containers, this object provides information about this
server.  In particular, it provides the slapd(8) version string. 
Example:

        dn: cn=Monitor
        monitoredInfo: OpenLDAP: slapd 2.X (Dec  7 2006 17:30:29)

Note: Examples in this section (and its subsections) have been trimmed
to show only key information.

20.4.1. Backends
----------------

The cn=Backends,cn=Monitor object provides a list of available
backends.  The list of available backends includes all builtin
backends, as well as those backends loaded by modules.  For example:

        dn: cn=Backends,cn=Monitor
        monitoredInfo: config
        monitoredInfo: ldif
        monitoredInfo: monitor
        monitoredInfo: mdb

This indicates the config, ldif, monitor, and mdb backends are
available.

The cn=Backends,cn=Monitor object is also a container for available
backend objects.  Each available backend object contains information
about a particular backend.  For example:

        dn: cn=Backend 0,cn=Backends,cn=Monitor
        monitoredInfo: config
        monitorRuntimeConfig: TRUE
        supportedControl: 2.16.840.1.113730.3.4.2
        seeAlso: cn=Database 0,cn=Databases,cn=Monitor

        dn: cn=Backend 1,cn=Backends,cn=Monitor
        monitoredInfo: ldif
        monitorRuntimeConfig: TRUE
        supportedControl: 2.16.840.1.113730.3.4.2

        dn: cn=Backend 2,cn=Backends,cn=Monitor
        monitoredInfo: monitor
        monitorRuntimeConfig: TRUE
        supportedControl: 2.16.840.1.113730.3.4.2
        seeAlso: cn=Database 2,cn=Databases,cn=Monitor

        dn: cn=Backend 3,cn=Backends,cn=Monitor
        monitoredInfo: mdb
        monitorRuntimeConfig: TRUE
        supportedControl: 1.3.6.1.1.12
        supportedControl: 2.16.840.1.113730.3.4.2
        supportedControl: 1.3.6.1.4.1.4203.666.5.2
        supportedControl: 1.2.840.113556.1.4.319
        supportedControl: 1.3.6.1.1.13.1
        supportedControl: 1.3.6.1.1.13.2
        supportedControl: 1.3.6.1.4.1.4203.1.10.1
        supportedControl: 1.2.840.113556.1.4.1413
        supportedControl: 1.3.6.1.4.1.4203.666.11.7.2

For each of these objects, monitorInfo indicates which backend the
information in the object is about.  For instance, the cn=Backend
5,cn=Backends,cn=Monitor object contains (in the example) information
about the mdb backend.

Attribute                          Description
.................................. .................................. 
monitoredInfo                      Name of backend
supportedControl                   supported LDAP control extensions
seeAlso                            Database objects of instances of
                                   this backend

20.4.2. Connections
-------------------

The main entry is empty; it should contain some statistics on the
number of connections.

Dynamic child entries are created for each open connection, with stats
on the activity on that connection (the format will be detailed
later). There are two special child entries that show the number of
total and current connections respectively.

For example:

Total Connections:

   dn: cn=Total,cn=Connections,cn=Monitor
   structuralObjectClass: monitorCounterObject
   monitorCounter: 4
   entryDN: cn=Total,cn=Connections,cn=Monitor
   subschemaSubentry: cn=Subschema
   hasSubordinates: FALSE

Current Connections:

   dn: cn=Current,cn=Connections,cn=Monitor
   structuralObjectClass: monitorCounterObject
   monitorCounter: 2
   entryDN: cn=Current,cn=Connections,cn=Monitor
   subschemaSubentry: cn=Subschema
   hasSubordinates: FALSE

20.4.3. Databases
-----------------

The main entry contains the naming context of each configured
database; the child entries contain, for each database, the type and
the naming context.

For example:

   dn: cn=Database 2,cn=Databases,cn=Monitor
   structuralObjectClass: monitoredObject
   monitoredInfo: monitor
   monitorIsShadow: FALSE
   monitorContext: cn=Monitor
   readOnly: FALSE
   entryDN: cn=Database 2,cn=Databases,cn=Monitor
   subschemaSubentry: cn=Subschema
   hasSubordinates: FALSE

20.4.4. Listener
----------------

It contains the description of the devices the server is currently
listening on:

   dn: cn=Listener 0,cn=Listeners,cn=Monitor
   structuralObjectClass: monitoredObject
   monitorConnectionLocalAddress: IP=0.0.0.0:389
   entryDN: cn=Listener 0,cn=Listeners,cn=Monitor
   subschemaSubentry: cn=Subschema
   hasSubordinates: FALSE

20.4.5. Log
-----------

It contains the currently active log items.  The Log subsystem allows
user modify operations on the description attribute, whose values MUST
be in the list of admittable log switches:

   Trace
   Packets
   Args
   Conns
   BER
   Filter
   Config
   ACL
   Stats
   Stats2
   Shell
   Parse
   Sync

These values can be added, replaced or deleted; they affect what
messages are sent to the syslog device. Custom values could be added
by custom modules.

20.4.6. Operations
------------------

It shows some statistics on the operations performed by the server:

   Initiated
   Completed

and for each operation type, i.e.:

   Bind
   Unbind
   Add
   Delete
   Modrdn
   Modify
   Compare
   Search
   Abandon
   Extended

There are too many types to list example here, so please try for
yourself using Monitor search example

20.4.7. Overlays
----------------

The main entry contains the type of overlays available at run-time;
the child entries, for each overlay, contain the type of the overlay.

It should also contain the modules that have been loaded if dynamic
overlays are enabled:

   # Overlays, Monitor
   dn: cn=Overlays,cn=Monitor
   structuralObjectClass: monitorContainer
   monitoredInfo: syncprov
   monitoredInfo: accesslog
   monitoredInfo: glue
   entryDN: cn=Overlays,cn=Monitor
   subschemaSubentry: cn=Subschema
   hasSubordinates: TRUE

20.4.8. SASL
------------

Currently empty.

20.4.9. Statistics
------------------

It shows some statistics on the data sent by the server:

   Bytes
   PDU
   Entries
   Referrals

e.g.

   # Entries, Statistics, Monitor
   dn: cn=Entries,cn=Statistics,cn=Monitor
   structuralObjectClass: monitorCounterObject
   monitorCounter: 612248
   entryDN: cn=Entries,cn=Statistics,cn=Monitor
   subschemaSubentry: cn=Subschema
   hasSubordinates: FALSE

20.4.10. Threads
----------------

It contains the maximum number of threads enabled at startup and the
current backload.

e.g.

   # Max, Threads, Monitor
   dn: cn=Max,cn=Threads,cn=Monitor
   structuralObjectClass: monitoredObject
   monitoredInfo: 16
   entryDN: cn=Max,cn=Threads,cn=Monitor
   subschemaSubentry: cn=Subschema
   hasSubordinates: FALSE

20.4.11. Time
-------------

It contains two child entries with the start time and the current time
of the server.

e.g.

Start time:

   dn: cn=Start,cn=Time,cn=Monitor
   structuralObjectClass: monitoredObject
   monitorTimestamp: 20061205124040Z
   entryDN: cn=Start,cn=Time,cn=Monitor
   subschemaSubentry: cn=Subschema
   hasSubordinates: FALSE

Current time:

   dn: cn=Current,cn=Time,cn=Monitor
   structuralObjectClass: monitoredObject
   monitorTimestamp: 20061207120624Z
   entryDN: cn=Current,cn=Time,cn=Monitor
   subschemaSubentry: cn=Subschema
   hasSubordinates: FALSE

20.4.12. TLS
------------

Currently empty.

20.4.13. Waiters
----------------

It contains the number of current read waiters.

e.g.

Read waiters:

   dn: cn=Read,cn=Waiters,cn=Monitor
   structuralObjectClass: monitorCounterObject
   monitorCounter: 7
   entryDN: cn=Read,cn=Waiters,cn=Monitor
   subschemaSubentry: cn=Subschema
   hasSubordinates: FALSE

Write waiters:

   dn: cn=Write,cn=Waiters,cn=Monitor
   structuralObjectClass: monitorCounterObject
   monitorCounter: 0
   entryDN: cn=Write,cn=Waiters,cn=Monitor
   subschemaSubentry: cn=Subschema
   hasSubordinates: FALSE

Add new monitored things here and discuss, referencing man pages and
present examples


21. Load Balancing with lloadd
==============================

As covered in the Replication chapter, replication is a fundamental
requirement for delivering a resilient enterprise deployment.  As such
there's a need for an LDAPv3 capable load balancer to spread the load
between the various directory instances.

lloadd(8) provides the capability to distribute LDAP v3 requests
between a set of running slapd instances.  It can run as a standalone
daemon lloadd, or as an embedded module running inside of slapd.

21.1. Overview
--------------

lloadd(8) was designed to handle LDAP loads. It is protocol-aware and
can balance LDAP loads on a per-operation basis rather than on a
per-connection basis.

lloadd(8) distributes the load across a set of slapd instances. The
client connects to the load balancer instance which forwards the
request to one of the servers and returns the response back to the
client.

21.2. When to use the OpenLDAP load balancer
--------------------------------------------

In general, the OpenLDAP load balancer spreads the load across
configured backend servers.  It does not perform so-called intelligent
routing. It does not understand semantics behind the operations being
performed by the clients.

More considerations:

     o    Servers are indistinguishable with respect to data contents.
           The exact same copy of data resides on every server.

     o    The sequence of operations isn't important.  For example,
          read after update isn't required by the client.

     o    If your client can handle both connection pooling and load
          distribution then it's preferable to lloadd.

     o    Clients with different requirements (e.g. a coherent session
          vs. simple but high traffic clients) are directed to
          separate lloadd configurations.

21.3. Directing operations to backends
--------------------------------------

21.3.1. Default behaviour
-------------------------

In the simplest configuration several backends would be configured
within a single roundrobin tier:

       feature proxyauthz

       bindconf bindmethod=simple
                binddn="cn=Manager,dc=example,dc=com"
                credentials=secret

       tier roundrobin
       backend-server uri=ldap://server1.example.com
                      numconns=5 bindconns=5
                      max-pending-ops=10 conn-max-pending=3
                      retry=5000
       backend-server uri=ldap://server2.example.com
                      numconns=5 bindconns=5
                      max-pending-ops=10 conn-max-pending=3
                      retry=5000

After startup lloadd will open 10 connections to each
ldap://server1.example.com and ldap://server2.example.com, 5 for
regular requests, where it will bind as cn=Manager,dc=example,dc=com,
and 5 dedicated to serving client Bind requests. If connection set up
fails, it will wait 5000ms (5 seconds) before making another attempt
to that server.

When a new Bind request comes from a client, it will be allocated to
one of the available bind connections, each of which can only carry
one request at a time. For other requests that need to be passed on to
the backends, backends are considered in order:

o    if the number of pending/in-flight for that backend is at or
     above 10, it is skipped

o    the first appropriate upstream connection is chosen:

     o    an idle bind connection for Bind requests

     o    a regular connection with less than 3 pending operations for
          other types of requests

o    if no such connection is available, the next backend in order is
     checked

o    if we go through the whole list without choosing an upstream
     connection, we return a failure to the client, either an
     LDAP_UNAVAILABLE if no connections of the appropriate type have
     been established at all or LDAP_BUSY otherwise

When a connection is chosen, the operation is forwarded and
response(s) returned to the client. Should that connection go away
before the final response is received, the client is notified with a
LDAP_OTHER failure code.

So long as feature proxyauthz is configured, every operation forwarded
over a regular connection has the PROXYAUTHZ control (RFC4370)
prepended indicating the client's bound identity, unless that identity
matches the binddn configured in bindconf.

If another tier is configured:

       tier roundrobin
       backend-server uri=ldap://fallback.example.com
                      numconns=5 bindconns=5
                      max-pending-ops=10 conn-max-pending=3
                      retry=5000

Backends in this tier will only be considered when lloadd would have
returned LDAP_UNAVAILABLE in the above case.

21.3.2. Alternate selection strategies
--------------------------------------

For various reasons, the roundrobin tier is appropriate in the
majority of use cases as it is both very scalable in terms of its
implementation and how its self-limiting interacts with backends when
multiple lloadd instances are being used at the same time.

Two alternative selection strategies have been implemented:

     o    tier weighted applies predefined weights to how often a
          backend is considered first

     o    tier bestof measures the time to first response from each
          backend, when a new operation needs to be forwarded, two
          backends are selected at random and the backend with better
          response time is considered first. If connections on neither
          backend can be used, selection falls back to the regular
          strategy used by the roundrobin backend

The weighted tier might be appropriate when servers have differing
load capacity. Due to its reinforced self-limiting feedback, the
bestof tier might be appropriate in large scale environments where
each backend's capacity/latency fluctuates widely and rapidly.

21.3.3. Coherence
-----------------

21.3.3.1. Write coherence
-------------------------

In default configurations, every operation submitted by the client is
either processed internally (e.g. StartTLS, Abandon, Unbind, ...) or
is forwarded to a connection of lloadd's choosing, independent of any
other other operation submitted by the same client.

There are certain traffic patterns where such such freedom is
undesirable and some kind of coherency is required. This applies to
write traffic, controls like Paged Results or many extended
operations.

Client's operations can be pinned to the same backend as the last
write operation:

       write_coherence 5

In this case, client's requests will be passed over to the same
backend (not necessarily over the same upstream connection) from the
moment a write request is passed on till at least 5 seconds have
elapsed since last write operation has finished.

       write_coherence -1

Here, there is no timeout and the moment a write request is passed on
to a backend, the client's operations will forever be passed on to
this backend.

In both cases above, this limitation is lifted the moment a Bind
request is received from the client connection.

21.3.3.2. Extended operations/controls
--------------------------------------

Many controls and Extended operations establish shared state on the
session. While lloadd implements some of these (StartTLS being one
example), it supports the administrator in defining how to deal with
those it does not implement special handling for.

       restrict_exop 1.1 reject
       # TXN Exop
       restrict_exop 1.3.6.1.1.21.1 connection
       # Password Modify Exop
       restrict_exop 1.3.6.1.4.1.4203.1.11.1 write

       # Paged Results Control
       restrict_control 1.2.840.113556.1.4.319 connection
       # Syncrepl
       restrict_control 1.3.6.1.4.1.4203.1.9.1 reject

The above configuration uses the special invalid OID of 1.1 to
instruct lloadd to reject any Extended operation it does not
recognize, except for Password Modify operation which is treated
according to write_coherence above and the LDAP transactions, where it
forwards all subsequent requests over to the same upstream connection.
Similarly, once a Paged results control is seen on an operation,
subsequent request will stick to the same upstream connection while
LDAP Syncrepl requests will be rejected outright.

With both restrict_exop and restrict_control, any such limitation is
lifted when a new Bind request comes in as any client state is assumed
to be reset.

When configuring these to anything else than reject, keep in mind that
many extensions have not been designed or implemented with a
multiplexing proxy like lloadd in mind and might open considerable
operational and/or security concerns when allowed.

21.4. Runtime configurations
----------------------------

It deploys in one of two ways:

1.   Standalone daemon: lloadd

2.   Loaded into the slapd daemon as a module: lloadd.la

It is recommended to run with the balancer module embedded in slapd
because dynamic configuration (cn=config) and the monitor backend are
then available.

Sample load balancer scenario:

** Unable to import figure load-balancer-scenario.png **

Figure: Load balancer sample scenario

1.   The LDAP client submits an LDAP operation to the load balancer
     daemon.

2.   The load balancer forwards the request to one of the backend
     instances in its pool of servers.

3.   The backend slapd server processes the request and returns the
     response to the load balancer instance.

4.   The load balancer returns the response to the client.  The
     client's unaware that it's connecting to a load balancer instead
     of slapd.

21.5. Build Notes
-----------------

To build the load balancer from source, follow the instructions in the
A Quick-Start Guide substituting the following commands:

1.   To configure as standalone daemon:

          ./configure --enable-balancer=yes

2.   To configure as embedded module to slapd:

          ./configure --enable-modules --enable-balancer=mod

21.6. Sample Runtime
--------------------

1.   To run embedded as lloadd  module:

           slapd [-h URLs]  [-f lloadd-config-file] [-u user] [-g
          group]

     o    the startup is the same as starting the slapd  daemon.

     o    URLs is for slapd management. The load balancer's listener
          URLs set in the configuration file or node. (more later)

2.   To run as standalone daemon:

           lloadd [-h URLs]  [-f lloadd-config-file] [-u user] [-g
          group]

     o    Other than a different daemon name, running standalone has
          the same options as starting slapd .

     o    -h URLs specify the lloadd's interface directly, there is no
          management interface.

For a complete list of options, checkout the man page lloadd.8

21.7. Configuring load balancer
-------------------------------

21.7.1. Common configuration options
------------------------------------

Many of the same configuration options as slapd. For complete list,
check the lloadd(5) man page.

       Edit the slapd.conf or cn=config configuration file.

To configure your working lloadd(8) you need to make the following
changes to your configuration file:

1.   include core.schema  (embedded only)

2.   TLSShareSlapdCTX { on | off }

3.   Other common TLS slapd options

4.   Setup argsfile/pidfile

5.   Setup moduleload path (embedded mode only)

6.   moduleload      lloadd.la

7.   loglevel, threads, ACL's

8.   backend lload  begin lloadd specific backend configurations

9.   listen ldap://:PORT  Specify listen port for load balancer

10.  feature proxyauthz  Use the proxy authZ control to forward
     client's identity

11.  io-threads INT  specify the number of threads to use for the
     connection manager.  The default is 1 and this is typically
     adequate for up to 16 CPU cores

21.7.2. Sample backend config
-----------------------------

Sample setup config for load balancer running in front of four slapd
instances.

backend lload

# The Load Balancer manages its own sockets, so they have to be separate
# from the ones slapd manages (as specified with the -h "URLS" option at
# startup).
listen ldap://:1389

# Enable authorization tracking
feature proxyauthz

# Specify the number of threads to use for the connection manager.  The default is 1 and this is typically adequate for up to 16 CPU cores.
# The value should be set to a power of 2:
io-threads  2

# If TLS is configured above, use the same context for the Load Balancer
# If using cn=config, this can be set to false and different settings
# can be used for the Load Balancer
TLSShareSlapdCTX true

# Authentication and other options (timeouts) shared between backends.
bindconf bindmethod=simple
         binddn=dc=example,dc=com credentials=secret
         network-timeout=5
         tls_cacert="/usr/local/etc/openldap/ca.crt"
         tls_cert="/usr/local/etc/openldap/host.crt"
         tls_key="/usr/local/etc/openldap/host.pem"


# List the backends we should relay operations to, they all have to be
# practically indistinguishable. Only TLS settings can be specified on
# a per-backend basis.

tier roundrobin
backend-server uri=ldap://ldaphost01 starttls=critical retry=5000
               max-pending-ops=50 conn-max-pending=10
               numconns=10 bindconns=5
backend-server uri=ldap://ldaphost02 starttls=critical retry=5000
               max-pending-ops=50 conn-max-pending=10
               numconns=10 bindconns=5
backend-server uri=ldap://ldaphost03 starttls=critical retry=5000
               max-pending-ops=50 conn-max-pending=10
               numconns=10 bindconns=5
backend-server uri=ldap://ldaphost04 starttls=critical retry=5000
               max-pending-ops=50 conn-max-pending=10
               numconns=10 bindconns=5

#######################################################################
# Monitor database
#######################################################################
database        monitor


22. Tuning
==========

This is perhaps one of the most important chapters in the guide,
because if you have not tuned slapd(8) correctly or grasped how to
design your directory and environment, you can expect very poor
performance.

Reading, understanding and experimenting using the instructions and
information in the following sections, will enable you to fully
understand how to tailor your directory server to your specific
requirements.

It should be noted that the following information has been collected
over time from our community based FAQ. So obviously the benefit of
this real world experience and advice should be of great value to the
reader.

22.1. Performance Factors
-------------------------

Various factors can play a part in how your directory performs on your
chosen hardware and environment. We will attempt to discuss these
here.

22.1.1. Memory
--------------

Scale your cache to use available memory and increase system memory if
you can.

22.1.2. Disks
-------------

Use fast filesystems, and conduct your own testing to see which
filesystem types perform best with your workload. (On our own Linux
testing, EXT2 and JFS tend to provide better write performance than
everything else, including newer filesystems like EXT4, BTRFS, etc.)

Use fast subsystems. Put each database on separate disks.

22.1.3. Network Topology
------------------------

http://www.openldap.org/faq/data/cache/363.html

Drawing here.

22.1.4. Directory Layout Design
-------------------------------

Reference to other sections and good/bad drawing here.

22.1.5. Expected Usage
----------------------

Discussion.

22.2. Indexes
-------------

22.2.1. Understanding how a search works
----------------------------------------

If you're searching on a filter that has been indexed, then the search
reads the index and pulls exactly the entries that are referenced by
the index. If the filter term has not been indexed, then the search
must read every single entry in the target scope and test to see if
each entry matches the filter. Obviously indexing can save a lot of
work when it's used correctly.

In back-mdb, indexes can only track a certain number of entries per
key (by default that number is 2^16 = 65536). If more entries' values
hash to this key, some/all of them will have to be represented by a
range of candidates, making the index less useful over time as
deletions cannot usually be tracked accurately.

22.2.2. What to index
---------------------

As a general rule, to make any use of indexes, you must set up an
equality index on objectClass:

        index objectClass eq

Then you should create indices to match the actual filter terms used
in search queries.

        index cn,sn,givenname,mail eq

Each attribute index can be tuned further by selecting the set of
index types to generate. For example, substring and approximate search
for organizations (o) may make little sense (and isn't like done very
often). And searching for userPassword likely makes no sense what so
ever.

General rule: don't go overboard with indexes. Unused indexes must be
maintained and hence can only slow things down.

See slapd.conf(5) and slapdindex(8) for more information

22.2.3. Presence indexing
-------------------------

If your client application uses presence filters and if the target
attribute exists on the majority of entries in your target scope, then
all of those entries are going to be read anyway, because they are
valid members of the result set. In a subtree where 100% of the
entries are going to contain the same attributes, the presence index
does absolutely NOTHING to benefit the search, because 100% of the
entries match that presence filter. As an example, setting a presence
index on objectClass provides no benefit since it is present on every
entry.

So the resource cost of generating the index is a complete waste of
CPU time, disk, and memory. Don't do it unless you know that it will
be used, and that the attribute in question occurs very infrequently
in the target data.

Almost no applications use presence filters in their search queries.
Presence indexing is pointless when the target attribute exists on the
majority of entries in the database. In most LDAP deployments,
presence indexing should not be done, it's just wasted overhead.

See the Logging section below on what to watch out for if you have a
frequently searched for attribute that is unindexed.

22.2.4. Equality indexing
-------------------------

Similarly to presence indexes, equality indexes are most useful if the
values searched for are uncommon. Most OpenLDAP indexes work by
hashing the normalised value and using the hash as the key. Hashing
behaviour depends on the matching rule syntax, some matching rules
also implement indexers that help speed up inequality (lower than,
...) queries.

Check the documentation and other parts of this guide if some indexes
are mandatory - e.g. to enable replication, it is expected you index
certain operational attributes, likewise if you rely on filters in ACL
processing.

Approximate indexes are usually identical to equality indexes unless a
matching rule explicitly implements it. As of OpenLDAP 2.5, only
directoryStringApproxMatch and IA5StringApproxMatch matchers and
indexers are implemented, currently using soundex or metaphone, with
metaphone being the default.

22.2.5. Substring indexing
--------------------------

Substring indexes work on splitting the value into short chunks and
then indexing those in a similar way to how equality index does. The
storage space needed to store all of this data is analogous to the
amount of data being indexed, which makes the indexes extremely
heavy-handed in most scenarios.

22.3. Logging
-------------

22.3.1. What log level to use
-----------------------------

The default of loglevel stats (256) is really the best bet. There's a
corollary to this when problems *do* arise, don't try to trace them
using syslog. Use the debug flag instead, and capture slapd's stderr
output. syslog is too slow for debug tracing, and it's inherently
lossy - it will throw away messages when it can't keep up. See
slapd.conf(5) or slapd-config(5) for more information on how to
configure the loglevel.

Contrary to popular belief, loglevel 0 is not ideal for production as
you won't be able to track when problems first arise.

22.3.2. What to watch out for
-----------------------------

The most common message you'll see that you should pay attention to
is:

       "<= mdb_equality_candidates: (foo) index_param failed (18)"

That means that some application tried to use an equality filter
(foo=<somevalue>) and attribute foo does not have an equality index.
If you see a lot of these messages, you should add the index. If you
see one every month or so, it may be acceptable to ignore it.

The default syslog level is stats (256) which logs the basic
parameters of each request; it usually produces 1-3 lines of output.
On Solaris and systems that only provide synchronous syslog, you may
want to turn it off completely, but usually you want to leave it
enabled so that you'll be able to see index messages whenever they
arise. On Linux you can configure syslogd to run asynchronously, in
which case the performance hit for moderate syslog traffic pretty much
disappears.

22.3.3. Improving throughput
----------------------------

You can improve logging performance on some systems by configuring
syslog not to sync the file system with every write (man
syslogd/syslog.conf). In Linux, you can prepend the log file name with
a "-" in syslog.conf. For example, if you are using the default LOCAL4
logging you could try:

       # LDAP logs
       LOCAL4.*         -/var/log/ldap

For syslog-ng, add or modify the following line in syslog-ng.conf:

       options { sync(n); };

where n is the number of lines which will be buffered before a write.

22.4. slapd(8) Threads
----------------------

slapd(8) can process requests via a configurable number of threads,
which in turn affects the in/out rate of connections.

This value should generally be a function of the number of "real"
cores on the system, for example on a server with 2 CPUs with one core
each, set this to 8, or 4 threads per real core.  This is a "read"
maximized value. The more threads that are configured per core, the
slower slapd(8) responds for "read" operations.  On the flip side, it
appears to handle write operations faster in a heavy write/low read
scenario.

The upper bound for good read performance appears to be 16 threads
(which also happens to be the default setting).


23. Troubleshooting
===================

If you're having trouble using OpenLDAP, get onto the
OpenLDAP-Software mailing list, or:

o    Browse the list archives at
     http://www.openldap.org/lists/#archives

o    Search the FAQ at http://www.openldap.org/faq/

o    Search the Issue Tracking System at http://www.openldap.org/its/

Chances are the problem has been solved and explained in detail many
times before.

23.1. User or Software errors?
------------------------------

More often than not, an error is caused by a configuration problem or
a misunderstanding of what you are trying to implement and/or achieve.

We will now attempt to discuss common user errors.

23.2. Checklist
---------------

The following checklist can help track down your problem. Please try
to use if before posting to the list, or in the rare circumstances of
reporting a bug.



1.   Use the slaptest tool to verify configurations before starting
     slapd



2.   Verify that slapd is listening to the specified port(s) (389 and
     636, generally) before trying the ldapsearch



3.   Can you issue an ldapsearch?



4.   If not, have you enabled complex ACLs without fully understanding
     them?



5.   Do you have a system wide LDAP setting pointing to the wrong LDAP
     Directory?



6.   Are you using TLS?



7.   Have your certificates expired?

23.3. OpenLDAP Bugs
-------------------

Sometimes you may encounter an actual OpenLDAP bug, in which case
please visit our Issue Tracking system http://www.openldap.org/its/
and report it. However, make sure it's not already a known bug or a
common user problem.

o    bugs in historic versions of OpenLDAP will not be considered;

o    bugs in released versions that are no longer present in the Git
     master branch, either because they have been fixed or because
     they no longer apply, will not be considered as well;

o    bugs in distributions of OpenLDAP software that are not related
     to the software as provided by OpenLDAP will not be considered;
     in those cases please refer to the distributor.

Note: Our Issue Tracking system is NOT for OpenLDAP Support, please
join our mailing Lists: http://www.openldap.org/lists/ for that.

The information you should provide in your bug report is discussed in
our FAQ-O-MATIC at http://www.openldap.org/faq/data/cache/59.html

23.4. 3rd party software error
------------------------------

The OpenLDAP Project only supports OpenLDAP software.

You may however seek commercial support
(http://www.openldap.org/support/) or join the general LDAP forum for
non-commercial discussions and information relating to LDAP at:
http://www.umich.edu/~dirsvcs/ldap/mailinglist.html

23.5. How to contact the OpenLDAP Project
-----------------------------------------

o    Mailing Lists: http://www.openldap.org/lists/

o    Project: http://www.openldap.org/project/

o    Issue Tracking: http://www.openldap.org/its/

23.6. How to present your problem
---------------------------------

23.7. Debugging slapd(8)
------------------------

After reading through the above sections and before e-mailing the
OpenLDAP lists, you might want to try out some of the following to
track down the cause of your problems:

o    A loglevel of stats (256) is generally a good first loglevel to
     use for getting information useful to list members on issues.
     This is the default loglevel if none is configured.

o    Running slapd -d -1 can often track down fairly simple issues,
     such as missing schemas and incorrect file permissions for the
     slapd user to things like certs

o    Check your logs for errors, as discussed at
     http://www.openldap.org/faq/data/cache/358.html

23.8. Commercial Support
------------------------

The firms listed at http://www.openldap.org/support/ offer technical
support services catering to OpenLDAP community.

The listing of any given firm should not be viewed as an endorsement
or recommendation of any kind, nor as otherwise indicating there
exists a business relationship or an affiliation between any listed
firm and the OpenLDAP Foundation or the OpenLDAP Project or its
contributors.


A. Changes Since Previous Release
=================================

The following sections attempt to summarize the new features and
changes in OpenLDAP software since the 2.5.x release and the OpenLDAP
Admin Guide.

A.1. New Features and Enhancements in 2.6
-----------------------------------------

A.1.1. New features in slapd
----------------------------

slapd now supports logging directly to a file, bypassing syslog.

A.1.2. New features in lloadd
-----------------------------

lloadd now supports additional balancing mechansims

A.2. Obsolete Features Removed From 2.6
---------------------------------------

These features were strongly deprecated in 2.5 and removed in 2.6.

A.2.1. back-ndb
---------------

The experimental and incomplete back-ndb backend was removed.


B. Upgrading from 2.5.x
=======================

The following sections attempt to document the steps you will need to
take in order to upgrade from the latest 2.5.x OpenLDAP version.

The normal upgrade procedure, as discussed in the Maintenance section,
should of course still be followed prior to doing any of this.

B.1. ppolicy overlay
--------------------

The pwdCheckModule option has been moved to the overlay configuration.
Existing settings in password policy entries will be ignored. It will
be necessary to use pwdUseCheckModule instead and add this
configuration directive to the overlay when upgrading if it is
currently in use.

B.2. lloadd backends
--------------------

Backends for lloadd are now grouped in tiers specifying the balancing
strategy. OpenLDAP 2.5 configurations must be updated to account for
this change.

B.3. monitor backend
--------------------

In 2.5 and prior, the managedInfo attribute in the cn=Log entry could
be used to change the loglevel of the slapd process. In 2.6,
monitorLogLevel can be used to change the slapd log level and
monitorDebugLevel can be used to change the slapd debug level.

B.4. contrib modules
--------------------

If still using the lastbind overlay with olcLastBindPrecision (when
olcLastBindForwardUpdates is needed), you will need to configure
precision on its backend entry instead and the overlay will honour it.
The old attribute is no longer accepted or supported.


C. Common errors encountered when using OpenLDAP Software
=========================================================

The following sections attempt to summarize the most common causes of
LDAP errors when using OpenLDAP

C.1. Common causes of LDAP errors
---------------------------------

C.1.1. ldap_*: Can't contact LDAP server
----------------------------------------

The Can't contact LDAP server error is usually returned when the LDAP
server cannot be contacted. This may occur for many reasons:

o    the LDAP server is not running; this can be checked by running,
     for example,

      telnet <host> <port>

replacing <host> and <port> with the hostname and the port the server
is supposed to listen on.

o    the client has not been instructed to contact a running server;
     with OpenLDAP command-line tools this is accomplished by
     providing the -H switch, whose argument is a valid LDAP url
     corresponding to the interface the server is supposed to be
     listening on.

C.1.2. ldap_*: No such object
-----------------------------

The no such object error is generally returned when the target DN of
the operation cannot be located. This section details reasons common
to all operations. You should also look for answers specific to the
operation (as indicated in the error message).

The most common reason for this error is non-existence of the named
object. First, check for typos.

Also note that, by default, a new directory server holds no objects
(except for a few system entries). So, if you are setting up a new
directory server and get this message, it may simply be that you have
yet to add the object you are trying to locate.

The error commonly occurs because a DN was not specified and a default
was not properly configured.

If you have a suffix specified in slapd.conf eg.

      suffix "dc=example,dc=com"

You should use

      ldapsearch -b 'dc=example,dc=com' '(cn=jane*)'

to tell it where to start the search.

The -b should be specified for all LDAP commands unless you have an
ldap.conf(5) default configured.

See ldapsearch(1), ldapmodify(1)

Also, slapadd(8) and its ancillary programs are very strict about the
syntax of the LDIF file.

Some liberties in the LDIF file may result in an apparently successful
creation of the database, but accessing some parts of it may be
difficult.

One known common error in database creation is putting a blank line
before the first entry in the LDIF file. There must be no leading
blank lines in the LDIF file.

It is generally recommended that ldapadd(1) be used instead of
slapadd(8) when adding new entries your directory. slapadd(8) should
be used to bulk load entries known to be valid.

Another cause of this message is a referral ({SECT:Constructing a
Distributed Directory Service}}) entry to an unpopulated directory.

Either remove the referral, or add a single record with the referral
base DN to the empty directory.

This error may also occur when slapd is unable to access the contents
of its database because of file permission problems. For instance, on
a Red Hat Linux system, slapd runs as user 'ldap'. When slapadd is run
as root to create a database from scratch, the contents of
/var/lib/ldap are created with user and group root and with permission
600, making the contents inaccessible to the slapd server.

C.1.3. ldap_*: Can't chase referral
-----------------------------------

This is caused by the line

      referral        ldap://root.openldap.org

In slapd.conf, it was provided as an example for how to use referrals
in the original file. However if your machine is not permanently
connected to the Internet, it will fail to find the server, and hence
produce an error message.

To resolve, just place a # in front of line and restart slapd or point
it to an available ldap server.

See also: ldapadd(1), ldapmodify(1) and slapd.conf(5)

C.1.4. ldap_*: server is unwilling to perform
---------------------------------------------

slapd will return an unwilling to perform error if the backend holding
the target entry does not support the given operation.

The password backend is only willing to perform searches. It will
return an unwilling to perform error for all other operations.

C.1.5. ldap_*: Insufficient access
----------------------------------

This error occurs when server denies the operation due to insufficient
access. This is usually caused by binding to a DN with insufficient
privileges (or binding anonymously) to perform the operation.

You can bind as the rootdn/rootpw specified in slapd.conf(5) to gain
full access. Otherwise, you must bind to an entry which has been
granted the appropriate rights through access controls.

C.1.6. ldap_*: Invalid DN syntax
--------------------------------

The target (or other) DN of the operation is invalid. This implies
that either the string representation of the DN is not in the required
form, one of the types in the attribute value assertions is not
defined, or one of the values in the attribute value assertions does
not conform to the appropriate syntax.

C.1.7. ldap_*: Referral hop limit exceeded
------------------------------------------

This error generally occurs when the client chases a referral which
refers itself back to a server it already contacted. The server
responds as it did before and the client loops. This loop is detected
when the hop limit is exceeded.

This is most often caused through misconfiguration of the server's
default referral. The default referral should not be itself:

That is, on ldap://myldap/ the default referral should not be
ldap://myldap/ (or any hostname/ip which is equivalent to myldap).

C.1.8. ldap_*: operations error
-------------------------------

In some versions of slapd(8), operationsError was returned instead of
other.

C.1.9. ldap_*: other error
--------------------------

The other result code indicates an internal error has occurred. While
the additional information provided with the result code might provide
some hint as to the problem, often one will need to consult the
server's log files.

C.1.10. ldap_add/modify: Invalid syntax
---------------------------------------

This error is reported when a value of an attribute does not conform
to syntax restrictions. Additional information is commonly provided
stating which value of which attribute was found to be invalid. Double
check this value and other values (the server will only report the
first error it finds).

Common causes include:

o    extraneous whitespace (especially trailing whitespace)

o    improperly encoded characters (LDAPv3 uses UTF-8 encoded Unicode)

o    empty values (few syntaxes allow empty values)

For certain syntax, like OBJECT IDENTIFIER (OID), this error can
indicate that the OID descriptor (a "short name") provided is
unrecognized. For instance, this error is returned if the objectClass
value provided is unrecognized.

C.1.11. ldap_add/modify: Object class violation
-----------------------------------------------

This error is returned with the entry to be added or the entry as
modified violates the object class schema rules. Normally additional
information is returned the error detailing the violation. Some of
these are detailed below.

Violations related to the entry's attributes:

      Attribute not allowed

A provided attribute is not allowed by the entry's object class(es).

      Missing required attribute

An attribute required by the entry's object class(es) was not
provided.

Violations related to the entry's class(es):

      Entry has no objectClass attribute

The entry did not state which object classes it belonged to.

      Unrecognized objectClass

One (or more) of the listed objectClass values is not recognized.

      No structural object class provided

None of the listed objectClass values is structural.

      Invalid structural object class chain

Two or more structural objectClass values are not in same structural
object class chain.

      Structural object class modification

Modify operation attempts to change the structural class of the entry.

      Instantiation of abstract objectClass.

An abstract class is not subordinate to any listed structural or
auxiliary class.

      Invalid structural object class

Other structural object class problem.

      No structuralObjectClass operational attribute

This is commonly returned when a shadow server is provided an entry
which does not contain the structuralObjectClass operational
attribute.

Note that the above error messages as well as the above answer assumes
basic knowledge of LDAP/X.500 schema.

C.1.12. ldap_add: No such object
--------------------------------

The "ldap_add: No such object" error is commonly returned if parent of
the entry being added does not exist. Add the parent entry first...

For example, if you are adding "cn=bob,dc=domain,dc=com" and you get:

      ldap_add: No such object

The entry "dc=domain,dc=com" likely doesn't exist. You can use
ldapsearch to see if does exist:

      ldapsearch -b 'dc=domain,dc=com' -s base '(objectclass=*)'

If it doesn't, add it. See A Quick-Start Guide for assistance.

Note: if the entry being added is the same as database suffix, it's
parent isn't required. i.e.: if your suffix is "dc=domain,dc=com",
"dc=com" doesn't need to exist to add "dc=domain,dc=com".

This error will also occur if you try to add any entry that the server
is not configured to hold.

For example, if your database suffix is "dc=domain,dc=com" and you
attempt to add "dc=domain2,dc=com", "dc=com", "dc=domain,dc=org",
"o=domain,c=us", or an other DN in the "dc=domain,dc=com" subtree, the
server will return a "No such object" (or referral) error.

slapd(8) will generally return "no global superior knowledge" as
additional information indicating its return noSuchObject instead of a
referral as the server is not configured with knowledge of a global
superior server.

C.1.13. ldap add: invalid structural object class chain
-------------------------------------------------------

This particular error refers to the rule about STRUCTURAL
objectclasses, which states that an object is of one STRUCTURAL class,
the structural class of the object. The object is said to belong to
this class, zero or more auxiliaries classes, and their super classes.

While all of these classes are commonly listed in the objectClass
attribute of the entry, one of these classes is the structural object
class of the entry. Thus, it is OK for an objectClass attribute to
contain inetOrgPerson, organizationalPerson, and person because they
inherit one from another to form a single super class chain. That is,
inetOrgPerson SUPs organizationPerson SUPs person. On the other hand,
it is invalid for both inetOrgPerson and account to be listed in
objectClass as inetOrgPerson and account are not part of the same
super class chain (unless some other class is also listed with is a
subclass of both).

To resolve this problem, one must determine which class will better
serve structural object class for the entry, adding this class to the
objectClass attribute (if not already present), and remove any other
structural class from the entry's objectClass attribute which is not a
super class of the structural object class.

Which object class is better depends on the particulars of the
situation. One generally should consult the documentation for the
applications one is using for help in making the determination.

C.1.14. ldap_add: no structuralObjectClass operational attribute
----------------------------------------------------------------

ldapadd(1) may error:

      adding new entry "uid=XXX,ou=People,o=campus,c=ru"
        ldap_add: Internal (implementation specific) error (80)
           additional info: no structuralObjectClass operational attribute

when slapd(8) cannot determine, based upon the contents of the
objectClass attribute, what the structural class of the object should
be.

C.1.15. ldap_add/modify/rename: Naming violation
------------------------------------------------

OpenLDAP's slapd checks for naming attributes and distinguished values
consistency, according to RFC 4512.

Naming attributes are those attributeTypes that appear in an entry's
RDN; distinguished values are the values of the naming attributes that
appear in an entry's RDN, e.g, in

      cn=Someone+mail=someone@example.com,dc=example,dc=com

the naming attributes are cn and mail, and the distinguished values
are Someone and someone@example.com.

OpenLDAP's slapd checks for consistency when:

o    adding an entry

o    modifying an entry, if the values of the naming attributes are
     changed

o    renaming an entry, if the RDN of the entry changes

Possible causes of error are:

o    the naming attributes are not present in the entry; for example:

                dn: dc=example,dc=com
                objectClass: organization
                o: Example
                # note: "dc: example" is missing

o    the naming attributes are present in the entry, but in the
     attributeType definition they are marked as:

     o    collective

     o    operational

     o    obsolete

o    the naming attributes are present in the entry, but the
     distinguished values are not; for example:

                dn: dc=example,dc=com
                objectClass: domain
                dc: foobar
                # note: "dc" is present, but the value is not "example"

o    the naming attributes are present in the entry, with the
     distinguished values, but the naming attributes:

     o    do not have an equality field, so equality cannot be
          asserted

     o    the matching rule is not supported (yet)

     o    the matching rule is not appropriate

o    the given distinguished values do not comply with their syntax

o    other errors occurred during the validation/normalization/match
     process; this is a catchall: look at previous logs for details in
     case none of the above apply to your case.

In any case, make sure that the attributeType definition for the
naming attributes contains an appropriate EQUALITY field; or that of
the superior, if they are defined based on a superior attributeType
(look at the SUP field). See RFC 4512 for details.

C.1.16. ldap_add/delete/modify/rename: no global superior knowledge
-------------------------------------------------------------------

If the target entry name places is not within any of the databases the
server is configured to hold and the server has no knowledge of a
global superior, the server will indicate it is unwilling to perform
the operation and provide the text "no global superior knowledge" as
additional text.

Likely the entry name is incorrect, or the server is not properly
configured to hold the named entry, or, in distributed directory
environments, a default referral was not configured.

C.1.17. ldap_bind: Insufficient access
--------------------------------------

Current versions of slapd(8) requires that clients have authentication
permission to attribute types used for authentication purposes before
accessing them to perform the bind operation. As all bind operations
are done anonymously (regardless of previous bind success), the auth
access must be granted to anonymous.

In the example ACL below grants the following access:

o    to anonymous users:

     o    permission to authenticate using values of userPassword

o    to authenticated users:

     o    permission to update (but not read) their userPassword

     o    permission to read any object excepting values of
          userPassword

All other access is denied.

        access to attr=userPassword
          by self =w
          by anonymous auth
        access *
          by self write
          by users read

C.1.18. ldap_bind: Invalid credentials
--------------------------------------

The error usually occurs when the credentials (password) provided does
not match the userPassword held in entry you are binding to.

The error can also occur when the bind DN specified is not known to
the server.

Check both! In addition to the cases mentioned above you should check
if the server denied access to userPassword on selected parts of the
directory. In fact, slapd always returns "Invalid credentials" in case
of failed bind, regardless of the failure reason, since other return
codes could reveal the validity of the user's name.

To debug access rules defined in slapd.conf, add "ACL" to log level.

C.1.19. ldap_bind: Protocol error
---------------------------------

There error is generally occurs when the LDAP version requested by the
client is not supported by the server.

The OpenLDAP Software 2.x server, by default, only accepts version 3
LDAP Bind requests but can be configured to accept a version 2 LDAP
Bind request.

Note: The 2.x server expects LDAPv3 [RFC4510] to be used when the
client requests version 3 and expects a limited LDAPv3 variant
(basically, LDAPv3 syntax and semantics in an LDAPv2 PDUs) to be used
when version 2 is expected.

This variant is also sometimes referred to as LDAPv2+, but differs
from the U-Mich LDAP variant in a number of ways.

C.1.20. ldap_modify: cannot modify object class
-----------------------------------------------

This message is commonly returned when attempting to modify the
objectClass attribute in a manner inconsistent with the LDAP/X.500
information model. In particular, it commonly occurs when one tries to
change the structure of the object from one class to another, for
instance, trying to change an 'apple' into a 'pear' or a 'fruit' into
a 'pear'.

Such changes are disallowed by the slapd(8) in accordance with LDAP
and X.500 restrictions.

C.1.21. ldap_sasl_interactive_bind_s: ...
-----------------------------------------

If you intended to bind using a DN and password and get an error from
ldap_sasl_interactive_bind_s, you likely forgot to provide a '-x'
option to the command. By default, SASL authentication is used. '-x'
is necessary to select "simple" authentication.

C.1.22. ldap_sasl_interactive_bind_s: No such Object
----------------------------------------------------

This indicates that LDAP SASL authentication function could not read
the Root DSE. The error will occur when the server doesn't provide a
root DSE. This may be due to access controls.

C.1.23. ldap_sasl_interactive_bind_s: No such attribute
-------------------------------------------------------

This indicates that LDAP SASL authentication function could read the
Root DSE but it contained no supportedSASLMechanism attribute.

The supportedSASLmechanism attribute lists mechanisms currently
available. The list may be empty because none of the supported
mechanisms are currently available. For example, EXTERNAL is listed
only if the client has established its identity by authenticating at a
lower level (e.g. TLS).

Note: the attribute may not be visible due to access controls

Note: SASL bind is the default for all OpenLDAP tools, e.g.
ldapsearch(1), ldapmodify(1). To force use of "simple" bind, use the
"-x" option. Use of "simple" bind is not recommended unless one has
adequate confidentiality protection in place (e.g. TLS/SSL, IPSEC).

C.1.24. ldap_sasl_interactive_bind_s: Unknown authentication method
-------------------------------------------------------------------

This indicates that none of the SASL authentication supported by the
server are supported by the client, or that they are too weak or
otherwise inappropriate for use by the client. Note that the default
security options disallows the use of certain mechanisms such as
ANONYMOUS and PLAIN (without TLS).

Note: SASL bind is the default for all OpenLDAP tools. To force use of
"simple" bind, use the "-x" option. Use of "simple" bind is not
recommended unless one has adequate confidentiality protection in
place (e.g. TLS/SSL, IPSEC).

C.1.25. ldap_sasl_interactive_bind_s: Local error (82)
------------------------------------------------------

Apparently not having forward and reverse DNS entries for the LDAP
server can result in this error.

C.1.26. ldap_search: Partial results and referral received
----------------------------------------------------------

This error is returned with the server responses to an LDAPv2 search
query with both results (zero or more matched entries) and references
(referrals to other servers). See also: ldapsearch(1).

If the updatedn on the replica does not exist, a referral will be
returned. It may do this as well if the ACL needs tweaking.

C.1.27. ldap_start_tls: Operations error
----------------------------------------

ldapsearch(1) and other tools will return

        ldap_start_tls: Operations error (1)
              additional info: TLS already started

When the user (though command line options and/or ldap.conf(5)) has
requested TLS (SSL) be started twice. For instance, when specifying
both "-H ldaps://server.do.main" and "-ZZ".

C.2. Other Errors
-----------------

C.2.1. ber_get_next on fd X failed errno=34 (Numerical result out of range)
---------------------------------------------------------------------------

This slapd error generally indicates that the client sent a message
that exceeded an administrative limit. See sockbuf_max_incoming and
sockbuf_max_incoming_auth configuration directives in slapd.conf(5).

C.2.2. ber_get_next on fd X failed errno=11 (Resource temporarily unavailable)
------------------------------------------------------------------------------

This message is not indicative of abnormal behavior or error. It
simply means that expected data is not yet available from the
resource, in this context, a network socket. slapd(8) will process the
data once it does becomes available.

C.2.3. daemon: socket() failed errno=97 (Address family not supported)
----------------------------------------------------------------------

This message indicates that the operating system does not support one
of the (protocol) address families which slapd(8) was configured to
support. Most commonly, this occurs when slapd(8) was configured to
support IPv6 yet the operating system kernel wasn't. In such cases,
the message can be ignored.

C.2.4. GSSAPI: gss_acquire_cred: Miscellaneous failure; Permission denied;
--------------------------------------------------------------------------

This message means that slapd is not running as root and, thus, it
cannot get its Kerberos 5 key from the keytab, usually file
/etc/krb5.keytab.

A keytab file is used to store keys that are to be used by services or
daemons that are started at boot time. It is very important that these
secrets are kept beyond reach of intruders.

That's why the default keytab file is owned by root and protected from
being read by others. Do not mess with these permissions, build a
different keytab file for slapd instead, and make sure it is owned by
the user that slapd runs as.

To do this, start kadmin, and enter the following commands:

     addprinc -randkey ldap/ldap.example.com@EXAMPLE.COM
     ktadd -k /etc/openldap/ldap.keytab ldap/ldap.example.com@EXAMPLE.COM

Then, on the shell, do:

     chown ldap:ldap /etc/openldap/ldap.keytab
     chmod 600 /etc/openldap/ldap.keytab

Now you have to tell slapd (well, actually tell the gssapi library in
Kerberos 5 that is invoked by Cyrus SASL) where to find the new
keytab. You do this by setting the environment variable KRB5_KTNAME
like this:

     export KRB5_KTNAME="FILE:/etc/openldap/ldap.keytab"

Set that environment variable on the slapd start script (Red Hat users
might find /etc/sysconfig/ldap a perfect place).

This only works if you are using MIT kerberos. It doesn't work with
Heimdal, for instance.

In Heimdal there is a function gsskrb5_register_acceptor_identity()
that sets the path of the keytab file you want to use. In Cyrus SASL 2
you can add

    keytab: /path/to/file

to your application's SASL config file to use this feature. This only
works with Heimdal.

C.2.5. access from unknown denied
---------------------------------

This related to TCP wrappers. See hosts_access(5) for more
information. in the log file: "access from unknown denied" This
related to TCP wrappers. See hosts_access(5) for more information. for
example: add the line "slapd: .hosts.you.want.to.allow" in
/etc/hosts.allow to get rid of the error.

C.2.6. ldap_read: want=# error=Resource temporarily unavailable
---------------------------------------------------------------

This message occurs normally. It means that pending data is not yet
available from the resource, a network socket. slapd(8) will process
the data once it becomes available.

C.2.7. `make test' fails
------------------------

Some times, `make test' fails at the very first test with an obscure
message like

    make test
    make[1]: Entering directory `/ldap_files/openldap-2.5.0/tests'
    make[2]: Entering directory `/ldap_files/openldap-2.5.0/tests'
    Initiating LDAP tests for MDB...
    Cleaning up test run directory leftover from previous run.
     Running ./scripts/all...
    >>>>> Executing all LDAP tests for mdb
    >>>>> Starting test000-rootdse ...
    running defines.sh
    Starting slapd on TCP/IP port 9011...
    Using ldapsearch to retrieve the root DSE...
    Waiting 5 seconds for slapd to start...
    ./scripts/test000-rootdse: line 40: 10607 Segmentation fault $SLAPD -f $CONF1 -h $URI1 -d $LVL $TIMING >$LOG1 2>&1
    Waiting 5 seconds for slapd to start...
    Waiting 5 seconds for slapd to start...
    Waiting 5 seconds for slapd to start...
    Waiting 5 seconds for slapd to start...
    Waiting 5 seconds for slapd to start...
    ./scripts/test000-rootdse: kill: (10607) - No such pid
    ldap_sasl_bind_s: Can't contact LDAP server (-1)
    >>>>> Test failed
    >>>>> ./scripts/test000-rootdse failed (exit 1)
    make[2]: *** [mdb-yes] Error 1
    make[2]: Leaving directory `/ldap_files/openldap-2.5.0/tests'
    make[1]: *** [test] Error 2
    make[1]: Leaving directory `/ldap_files/openldap-2.5.0/tests'
    make: *** [test] Error 2

or so. Usually, the five lines

Waiting 5 seconds for slapd to start...

indicate that slapd didn't start at all.

In tests/testrun/slapd.1.log there is a full log of what slapd wrote
while trying to start. The log level can be increased by setting the
environment variable SLAPD_DEBUG to the corresponding value; see
loglevel in slapd.conf(5) for the meaning of log levels.

A typical reason for this behavior is a runtime link problem, i.e.
slapd cannot find some dynamic libraries it was linked against. Try
running ldd(1) on slapd (for those architectures that support runtime
linking).

There might well be other reasons; the contents of the log file should
help clarifying them.

Tests that fire up multiple instances of slapd typically log to
tests/testrun/slapd.<n>.log, with a distinct <n> for each instance of
slapd; list tests/testrun/ for possible values of <n>.

C.2.8. ldap_*: Internal (implementation specific) error (80) - additional info: entry index delete failed
---------------------------------------------------------------------------------------------------------

This seems to be related with wrong ownership of the MDB's dir
(/var/lib/ldap) and files. The files must be owned by the user that
slapd runs as.

    chown -R ldap:ldap /var/lib/ldap

fixes it in Debian

C.2.9. ldap_sasl_interactive_bind_s: Can't contact LDAP server (-1)
-------------------------------------------------------------------

Using SASL, when a client contacts LDAP server, the slapd service dies
immediately and client gets an error :

     SASL/GSSAPI authentication started ldap_sasl_interactive_bind_s: Can't contact LDAP server (-1)

Then check the slapd service, it stopped.


D. Recommended OpenLDAP Software Dependency Versions
====================================================

This appendix details the recommended versions of the software that
OpenLDAP depends on.

Please read the Prerequisite software section for more information on
the following software dependencies.

D.1. Dependency Versions
------------------------

Table 8.5: OpenLDAP Software Dependency Versions

Feature                Software                Version
...................... ....................... ...................... 
Transport Layer
Security:
                       OpenSSL                 1.1.1+
                       GnuTLS                  3.6.0+
Simple Authentication  Cyrus SASL              2.1.27+
and Security Layer
LDAP Load Balancer     libevent                2.1+
Threads:               POSIX pthreads          Version


E. Real World OpenLDAP Deployments and Examples
===============================================

Examples and discussions


F. OpenLDAP Software Contributions
==================================

The following sections attempt to summarize the various contributions
in OpenLDAP software, as found in openldap_src/contrib

F.1. Client APIs
----------------

Intro and discuss

F.1.1. ldapc++
--------------

Intro and discuss

F.1.2. ldaptcl
--------------

Intro and discuss

F.2. Overlays
-------------

F.2.1. acl
----------

Plugins that implement access rules.  Currently only posixGroup, which
implements access control based on posixGroup membership.

F.2.2. addpartial
-----------------

Treat Add requests as Modify requests if the entry exists.

F.2.3. allop
------------

Return operational attributes for root DSE even when not requested,
since some clients expect this.

F.2.4. autogroup
----------------

Automated updates of group memberships.

F.2.5. comp_match
-----------------

Component Matching rules (RFC 3687).

F.2.6. denyop
-------------

Deny selected operations, returning unwillingToPerform.

F.2.7. dsaschema
----------------

Permit loading DSA-specific schema, including operational attrs.

F.2.8. lastmod
--------------

Track the time of the last write operation to a database.

F.2.9. nops
-----------

Remove null operations, e.g. changing a value to same as before.

F.2.10. nssov
-------------

Handle NSS lookup requests through a local Unix Domain socket.

F.2.11. passwd
--------------

Support additional password mechanisms.

F.2.12. proxyOld
----------------

Proxy Authorization compatibility with obsolete internet-draft.

F.2.13. smbk5pwd
----------------

Make the PasswordModify Extended Operation update Kerberos keys and
Samba password hashes as well as userPassword.

F.2.14. trace
-------------

Trace overlay invocation.

F.2.15. usn
-----------

Maintain usnCreated and usnChanged attrs similar to Microsoft AD.

F.3. Tools
----------

Intro and discuss

F.3.1. Statistic Logging
------------------------

statslog

F.4. SLAPI Plugins
------------------

Intro and discuss

F.4.1. addrdnvalues
-------------------

More


G. Configuration File Examples
==============================

G.1. slapd.conf
---------------

G.2. ldap.conf
--------------

G.3. a-n-other.conf
-------------------


H. LDAP Result Codes
====================

For the purposes of this guide, we have incorporated the standard LDAP
result codes from Appendix A.  LDAP Result Codes of RFC4511, a copy of
which can be found in doc/rfc of the OpenLDAP source code.

We have expanded the description of each error in relation to the
OpenLDAP toolsets. LDAP extensions may introduce extension-specific
result codes, which are not part of RFC4511. OpenLDAP returns the
result codes related to extensions it implements. Their meaning is
documented in the extension they are related to.

H.1. Non-Error Result Codes
---------------------------

These result codes (called "non-error" result codes) do not indicate
an error condition:

        success (0),
        compareFalse (5),
        compareTrue (6),
        referral (10), and
        saslBindInProgress (14).

The success, compareTrue, and compareFalse result codes indicate
successful completion (and, hence, are referred to as "successful"
result codes).

The referral and saslBindInProgress result codes indicate the client
needs to take additional action to complete the operation.

H.2. Result Codes
-----------------

Existing LDAP result codes are described as follows:

H.3. success (0)
----------------

Indicates the successful completion of an operation.

Note: this code is not used with the Compare operation.  See
compareFalse (5) and compareTrue (6).

H.4. operationsError (1)
------------------------

Indicates that the operation is not properly sequenced with relation
to other operations (of same or different type).

For example, this code is returned if the client attempts to StartTLS
(RFC4511 Section 4.14) while there are other uncompleted operations or
if a TLS layer was already installed.

H.5. protocolError (2)
----------------------

Indicates the server received data that is not well-formed.

For Bind operation only, this code is also used to indicate that the
server does not support the requested protocol version.

For Extended operations only, this code is also used to indicate that
the server does not support (by design or configuration) the Extended
operation associated with the requestName.

For request operations specifying multiple controls, this may be used
to indicate that the server cannot ignore the order of the controls as
specified, or that the combination of the specified controls is
invalid or unspecified.

H.6. timeLimitExceeded (3)
--------------------------

Indicates that the time limit specified by the client was exceeded
before the operation could be completed.

H.7. sizeLimitExceeded (4)
--------------------------

Indicates that the size limit specified by the client was exceeded
before the operation could be completed.

H.8. compareFalse (5)
---------------------

Indicates that the Compare operation has successfully completed and
the assertion has evaluated to FALSE or Undefined.

H.9. compareTrue (6)
--------------------

Indicates that the Compare operation has successfully completed and
the assertion has evaluated to TRUE.

H.10. authMethodNotSupported (7)
--------------------------------

Indicates that the authentication method or mechanism is not
supported.

H.11. strongerAuthRequired (8)
------------------------------

Indicates the server requires strong(er) authentication in order to
complete the operation.

When used with the Notice of Disconnection operation, this code
indicates that the server has detected that an established security
association between the client and server has unexpectedly failed or
been compromised.

H.12. referral (10)
-------------------

Indicates that a referral needs to be chased to complete the operation
(see RFC4511 Section 4.1.10).

H.13. adminLimitExceeded (11)
-----------------------------

Indicates that an administrative limit has been exceeded.

H.14. unavailableCriticalExtension (12)
---------------------------------------

Indicates a critical control is unrecognized (see RFC4511 Section
4.1.11).

H.15. confidentialityRequired (13)
----------------------------------

Indicates that data confidentiality protections are required.

H.16. saslBindInProgress (14)
-----------------------------

Indicates the server requires the client to send a new bind request,
with the same SASL mechanism, to continue the authentication process
(see RFC4511 Section 4.2).

H.17. noSuchAttribute (16)
--------------------------

Indicates that the named entry does not contain the specified
attribute or attribute value.

H.18. undefinedAttributeType (17)
---------------------------------

Indicates that a request field contains an unrecognized attribute
description.

H.19. inappropriateMatching (18)
--------------------------------

Indicates that an attempt was made (e.g., in an assertion) to use a
matching rule not defined for the attribute type concerned.

H.20. constraintViolation (19)
------------------------------

Indicates that the client supplied an attribute value that does not
conform to the constraints placed upon it by the data model.

For example, this code is returned when multiple values are supplied
to an attribute that has a SINGLE-VALUE constraint.

H.21. attributeOrValueExists (20)
---------------------------------

Indicates that the client supplied an attribute or value to be added
to an entry, but the attribute or value already exists.

H.22. invalidAttributeSyntax (21)
---------------------------------

Indicates that a purported attribute value does not conform to the
syntax of the attribute.

H.23. noSuchObject (32)
-----------------------

Indicates that the object does not exist in the DIT.

H.24. aliasProblem (33)
-----------------------

Indicates that an alias problem has occurred.  For example, the code
may used to indicate an alias has been dereferenced that names no
object.

H.25. invalidDNSyntax (34)
--------------------------

Indicates that an LDAPDN or RelativeLDAPDN field (e.g., search base,
target entry, ModifyDN newrdn, etc.) of a request does not conform to
the required syntax or contains attribute values that do not conform
to the syntax of the attribute's type.

H.26. aliasDereferencingProblem (36)
------------------------------------

Indicates that a problem occurred while dereferencing an alias. 
Typically, an alias was encountered in a situation where it was not
allowed or where access was denied.

H.27. inappropriateAuthentication (48)
--------------------------------------

Indicates the server requires the client that had attempted to bind
anonymously or without supplying credentials to provide some form of
credentials.

H.28. invalidCredentials (49)
-----------------------------

Indicates that the provided credentials (e.g., the user's name and
password) are invalid.

H.29. insufficientAccessRights (50)
-----------------------------------

Indicates that the client does not have sufficient access rights to
perform the operation.

H.30. busy (51)
---------------

Indicates that the server is too busy to service the operation.

H.31. unavailable (52)
----------------------

Indicates that the server is shutting down or a subsystem necessary to
complete the operation is offline.

H.32. unwillingToPerform (53)
-----------------------------

Indicates that the server is unwilling to perform the operation.

H.33. loopDetect (54)
---------------------

Indicates that the server has detected an internal loop (e.g., while
dereferencing aliases or chaining an operation).

H.34. namingViolation (64)
--------------------------

Indicates that the entry's name violates naming restrictions.

H.35. objectClassViolation (65)
-------------------------------

Indicates that the entry violates object class restrictions.

H.36. notAllowedOnNonLeaf (66)
------------------------------

Indicates that the operation is inappropriately acting upon a non-leaf
entry.

H.37. notAllowedOnRDN (67)
--------------------------

Indicates that the operation is inappropriately attempting to remove a
value that forms the entry's relative distinguished name.

H.38. entryAlreadyExists (68)
-----------------------------

Indicates that the request cannot be fulfilled (added, moved, or
renamed) as the target entry already exists.

H.39. objectClassModsProhibited (69)
------------------------------------

Indicates that an attempt to modify the object class(es) of an entry's
'objectClass' attribute is prohibited.

For example, this code is returned when a client attempts to modify
the structural object class of an entry.

H.40. affectsMultipleDSAs (71)
------------------------------

Indicates that the operation cannot be performed as it would affect
multiple servers (DSAs).

H.41. other (80)
----------------

Indicates the server has encountered an internal error.


I. Glossary
===========

I.1. Terms
----------

Term                               Definition
.................................. .................................. 
3DES                               Triple DES
ABNF                               Augmented Backus-Naur Form
ACDF                               Access Control Decision Function
ACE                                ASCII Compatible Encoding
ASCII                              American Standard Code for
                                   Information Interchange
ACID                               Atomicity, Consistency, Isolation,
                                   and Durability
ACI                                Access Control Information
ACL                                Access Control List
AES                                Advance Encryption Standard
ABI                                Application Binary Interface
API                                Application Program Interface
ASN.1                              Abstract Syntax Notation - One
AVA                                Attribute Value Assertion
AuthcDN                            Authentication DN
AuthcId                            Authentication Identity
AuthzDN                            Authorization DN
AuthzId                            Authorization Identity
BCP                                Best Current Practice
BER                                Basic Encoding Rules
BNF                                Backus-Naur Form
C                                  The C Programming Language
CA                                 Certificate Authority
CER                                Canonical Encoding Rules
CLDAP                              Connection-less LDAP
CN                                 Common Name
CRAM-MD5                           SASL MD5 Challenge/Response
                                   Authentication Mechanism
CRL                                Certificate Revocation List
DAP                                Directory Access Protocol
DC                                 Domain Component
DER                                Distinguished Encoding Rules
DES                                Data Encryption Standard
DIB                                Directory Information Base
DIGEST-MD5                         SASL Digest MD5 Authentication
                                   Mechanism
DISP                               Directory Information Shadowing
                                   Protocol
DIT                                Directory Information Tree
DNS                                Domain Name System
DN                                 Distinguished Name
DOP                                Directory Operational Binding
                                   Management Protocol
DSAIT                              DSA Information Tree
DSA                                Directory System Agent
DSE                                DSA-specific Entry
DSP                                Directory System Protocol
DS                                 Draft Standard
DUA                                Directory User Agent
EXTERNAL                           SASL External Authentication
                                   Mechanism
FAQ                                Frequently Asked Questions
FTP                                File Transfer Protocol
FYI                                For Your Information
GSER                               Generic String Encoding Rules
GSS-API                            Generic Security Service
                                   Application Program Interface
GSSAPI                             SASL Kerberos V GSS-API
                                   Authentication Mechanism
I-D                                Internet-Draft
IA5                                International Alphabet 5
IDNA                               Internationalized Domain Names in
                                   Applications
IDN                                Internationalized Domain Name
ID                                 Identifier
IDL                                Index Data Lookups
IP                                 Internet Protocol
IPC                                Inter-process communication
IPsec                              Internet Protocol Security
IPv4                               Internet Protocol, version 4
IPv6                               Internet Protocol, version 6
ITS                                Issue Tracking System
JPEG                               Joint Photographic Experts Group
Kerberos                           Kerberos Authentication Service
LBER                               Lightweight BER
LDAP                               Lightweight Directory Access
                                   Protocol
LDAP Sync                          LDAP Content Synchronization
LDAPv3                             LDAP, version 3
LDIF                               LDAP Data Interchange Format
LMDB                               Lightning Memory-Mapped Database
MD5                                Message Digest 5
MDB                                Memory-Mapped Database (Backend)
MIB                                Management Information Base
MODDN                              Modify DN
MODRDN                             Modify RDN
NSSR                               Non-specific Subordinate Reference
OID                                Object Identifier
OSI                                Open Systems Interconnect
OTP                                One Time Password
PDU                                Protocol Data Unit
PEM                                Privacy Enhanced eMail
PEN                                Private Enterprise Number
PKCS                               Public Key Cryptosystem
PKI                                Public Key Infrastructure
PKIX                               Public Key Infrastructure (X.509)
PLAIN                              SASL Plaintext Password
                                   Authentication Mechanism
POSIX                              Portable Operating System
                                   Interface
PS                                 Proposed Standard
RDN                                Relative Distinguished Name
RFC                                Request for Comments
RPC                                Remote Procedure Call
RXER                               Robust XML Encoding Rules
SASL                               Simple Authentication and Security
                                   Layer
SDF                                Simple Document Format
SDSE                               Shadowed DSE
SHA1                               Secure Hash Algorithm 1
SLAPD                              Standalone LDAP Daemon
SLURPD                             Standalone LDAP Update Replication
                                   Daemon
SMTP                               Simple Mail Transfer Protocol
SNMP                               Simple Network Management Protocol
SQL                                Structured Query Language
SRP                                Secure Remote Password
SSF                                Security Strength Factor
SSL                                Secure Socket Layer
STD                                Internet Standard
TCP                                Transmission Control Protocol
TLS                                Transport Layer Security
UCS                                Universal Multiple-Octet Coded
                                   Character Set
UDP                                User Datagram Protocol
UID                                User Identifier
Unicode                            The Unicode Standard
UNIX                               Unix
URI                                Uniform Resource Identifier
URL                                Uniform Resource Locator
URN                                Uniform Resource Name
UTF-8                              8-bit UCS/Unicode Transformation
                                   Format
UTR                                Unicode Technical Report
UUID                               Universally Unique Identifier
WWW                                World Wide Web
X.500                              X.500 Directory Services
X.509                              X.509 Public Key and Attribute
                                   Certificate Frameworks
XED                                XML Enabled Directory
XER                                XML Encoding Rules
XML                                Extensible Markup Language
syncrepl                           LDAP Sync-based Replication
lloadd                             LDAP Load Balancer

I.2. Related Organizations
--------------------------

Name                   Long                    Jump
...................... ....................... ...................... 
ANSI                   American National       https://www.ansi.org/
                       Standards Institute
BSI                    British Standards       https://www.bsigroup.com/en-GB/
                       Institute
COSINE                 Co-operation and Open
                       Systems Interconnection
                       in Europe
CPAN                   Comprehensive Perl      https://www.cpan.org/
                       Archive Network
Cyrus                  Project Cyrus           https://www.cyrusimap.org/
FSF                    Free Software           https://www.fsf.org/
                       Foundation
GNU                    GNU Not Unix Project    https://www.gnu.org/
IAB                    Internet Architecture   https://www.iab.org/
                       Board
IANA                   Internet Assigned       https://www.iana.org/
                       Numbers Authority
IEEE                   Institute of Electrical https://www.ieee.org
                       and Electronics
                       Engineers
IESG                   Internet Engineering    https://www.ietf.org/about/groups/iesg/
                       Steering Group
IETF                   Internet Engineering    https://www.ietf.org/
                       Task Force
IRTF                   Internet Research Task  https://irtf.org/
                       Force
ISO                    International Standards https://www.iso.org/
                       Organisation
ISOC                   Internet Society        https://www.internetsociety.org/
ITU                    International           https://www.itu.int/
                       Telecommunication Union
OLF                    OpenLDAP Foundation     https://www.openldap.org/foundation/
OLP                    OpenLDAP Project        https://www.openldap.org/project/
OpenSSL                OpenSSL Project         https://www.openssl.org/
RFC Editor             RFC Editor              https://www.rfc-editor.org/
Oracle                 Oracle Corporation      https://www.oracle.com/
UM                     University of Michigan  https://www.umich.edu/
UMLDAP                 University of Michigan  https://web.archive.org/web/20160302011357/http://www.umich.edu/~dirsvcs/ldap/ldap.html
                       LDAP Team

I.3. Related Products
---------------------

Name                               Jump
.................................. .................................. 
SDF                                https://metacpan.org/release/sdf
Cyrus                              https://www.cyrusimap.org/
Cyrus SASL                         https://www.cyrusimap.org/sasl/
Git                                https://git-scm.com/
GNU                                https://www.gnu.org/software/
GnuTLS                             https://gnutls.org/
Heimdal                            https://github.com/heimdal/
JLDAP                              https://www.openldap.org/jldap/
libevent                           https://libevent.org/
MIT Kerberos                       https://web.mit.edu/kerberos/
OpenLDAP                           https://www.openldap.org/
OpenLDAP FAQ                       https://www.openldap.org/faq/
OpenLDAP ITS                       https://bugs.openldap.org/
OpenLDAP Software                  https://www.openldap.org/software/
OpenSSL                            https://www.openssl.org/
Perl                               https://www.perl.org/
UMLDAP                             https://web.archive.org/web/20160302011357/http://www.umich.edu/~dirsvcs/ldap/ldap.html

I.4. References
---------------

Reference         Document         Status            Jump
................. ................ ................. ................ 
UM-GUIDE          The SLAPD and    O                 https://web.archive.org/web/20170809071245/http://www.umich.edu/~dirsvcs/ldap/doc/guides/slapd/guide.pdf
                  SLURPD
                  Administrators
                  Guide
RFC2079           Definition of an PS                https://www.rfc-editor.org/rfc/rfc2079.txt
                  X.500 Attribute
                  Type and an
                  Object Class to
                  Hold Uniform
                  Resource
                  Identifiers
RFC2296           Use of Language  PS                https://www.rfc-editor.org/rfc/rfc2296.txt
                  Codes in LDAP
RFC2307           An Approach for  X                 https://www.rfc-editor.org/rfc/rfc2307.txt
                  Using LDAP as a
                  Network
                  Information
                  Service
RFC2589           Lightweight      PS                https://www.rfc-editor.org/rfc/rfc2589.txt
                  Directory Access
                  Protocol (v3):
                  Extensions for
                  Dynamic
                  Directory
                  Services
RFC2798           Definition of    I                 https://www.rfc-editor.org/rfc/rfc2798.txt
                  the
                  inetOrgPerson
                  LDAP Object
                  Class
RFC2831           Using Digest     PS                https://www.rfc-editor.org/rfc/rfc2831.txt
                  Authentication
                  as a SASL
                  Mechanism
RFC2849           The LDAP Data    PS                https://www.rfc-editor.org/rfc/rfc2849.txt
                  Interchange
                  Format
RFC3088           OpenLDAP Root    X                 https://www.rfc-editor.org/rfc/rfc3088.txt
                  Service
RFC3296           Named            PS                https://www.rfc-editor.org/rfc/rfc3296.txt
                  Subordinate
                  References in
                  LDAP
RFC3384           Lightweight      I                 https://www.rfc-editor.org/rfc/rfc3384.txt
                  Directory Access
                  Protocol
                  (version 3)
                  Replication
                  Requirements
RFC3494           Lightweight      I                 https://www.rfc-editor.org/rfc/rfc3494.txt
                  Directory Access
                  Protocol version
                  2 (LDAPv2) to
                  Historic Status
RFC4013           SASLprep:        PS                https://www.rfc-editor.org/rfc/rfc4013.txt
                  Stringprep
                  Profile for User
                  Names and
                  Passwords
RFC4346           The Transport    PS                https://www.rfc-editor.org/rfc/rfc4346.txt
                  Layer Security
                  (TLS) Protocol,
                  Version 1.1
RFC4370           Lightweight      PS                https://www.rfc-editor.org/rfc/rfc4370.txt
                  Directory Access
                  Protocol (LDAP)
                  Proxied
                  Authorization
                  Control
RFC4422           Simple           PS                https://www.rfc-editor.org/rfc/rfc4422.txt
                  Authentication
                  and Security
                  Layer (SASL)
RFC4510           Lightweight      PS                https://www.rfc-editor.org/rfc/rfc4510.txt
                  Directory Access
                  Protocol (LDAP):
                  Technical
                  Specification
                  Roadmap
RFC4511           Lightweight      PS                https://www.rfc-editor.org/rfc/rfc4511.txt
                  Directory Access
                  Protocol (LDAP):
                  The Protocol
RFC4512           Lightweight      PS                https://www.rfc-editor.org/rfc/rfc4512.txt
                  Directory Access
                  Protocol (LDAP):
                  Directory
                  Information
                  Models
RFC4513           Lightweight      PS                https://www.rfc-editor.org/rfc/rfc4513.txt
                  Directory Access
                  Protocol (LDAP):
                  Authentication
                  Methods and
                  Security
                  Mechanisms
RFC4514           Lightweight      PS                https://www.rfc-editor.org/rfc/rfc4514.txt
                  Directory Access
                  Protocol (LDAP):
                  String
                  Representation
                  of Distinguished
                  Names
RFC4515           Lightweight      PS                https://www.rfc-editor.org/rfc/rfc4515.txt
                  Directory Access
                  Protocol (LDAP):
                  String
                  Representation
                  of Search
                  Filters
RFC4516           Lightweight      PS                https://www.rfc-editor.org/rfc/rfc4516.txt
                  Directory Access
                  Protocol (LDAP):
                  Uniform Resource
                  Locator
RFC4517           Lightweight      PS                https://www.rfc-editor.org/rfc/rfc4517.txt
                  Directory Access
                  Protocol (LDAP):
                  Syntaxes and
                  Matching Rules
RFC4518           Lightweight      PS                https://www.rfc-editor.org/rfc/rfc4518.txt
                  Directory Access
                  Protocol (LDAP):
                  Internationalized
                  String
                  Preparation
RFC4519           Lightweight      PS                https://www.rfc-editor.org/rfc/rfc4519.txt
                  Directory Access
                  Protocol (LDAP):
                  Schema for User
                  Applications
RFC4520           IANA             BCP               https://www.rfc-editor.org/rfc/rfc4520.txt
                  Considerations
                  for LDAP
RFC4533           The Lightweight  X                 https://www.rfc-editor.org/rfc/rfc4533.txt
                  Directory Access
                  Protocol (LDAP)
                  Content
                  Synchronization
                  Operation
Chu-LDAPI         Using LDAP Over  ID                https://tools.ietf.org/html/draft-chu-ldap-ldapi-00
                  IPC Mechanisms


J. Generic configure Instructions
=================================

Basic Installation
==================

   These are generic installation instructions.

   The `configure' shell script attempts to guess correct values for
various system-dependent variables used during compilation.  It uses
those values to create a `Makefile' in each directory of the package.
It may also create one or more `.h' files containing system-dependent
definitions.  Finally, it creates a shell script `config.status' that
you can run in the future to recreate the current configuration, a file
`config.cache' that saves the results of its tests to speed up
reconfiguring, and a file `config.log' containing compiler output
(useful mainly for debugging `configure').

   If you need to do unusual things to compile the package, please try
to figure out how `configure' could check whether to do them, and mail
diffs or instructions to the address given in the `README' so they can
be considered for the next release.  If at some point `config.cache'
contains results you don't want to keep, you may remove or edit it.

   The file `configure.in' is used to create `configure' by a program
called `autoconf'.  You only need `configure.in' if you want to change
it or regenerate `configure' using a newer version of `autoconf'.

The simplest way to compile this package is:

  1. `cd' to the directory containing the package's source code and type
     `./configure' to configure the package for your system.  If you're
     using `csh' on an old version of System V, you might need to type
     `sh ./configure' instead to prevent `csh' from trying to execute
     `configure' itself.

     Running `configure' takes awhile.  While running, it prints some
     messages telling which features it is checking for.

  2. Type `make' to compile the package.

  3. Optionally, type `make check' to run any self-tests that come with
     the package.

  4. Type `make install' to install the programs and any data files and
     documentation.

  5. You can remove the program binaries and object files from the
     source code directory by typing `make clean'.  To also remove the
     files that `configure' created (so you can compile the package for
     a different kind of computer), type `make distclean'.  There is
     also a `make maintainer-clean' target, but that is intended mainly
     for the package's developers.  If you use it, you may have to get
     all sorts of other programs in order to regenerate files that came
     with the distribution.

Compilers and Options
=====================

   Some systems require unusual options for compilation or linking that
the `configure' script does not know about.  You can give `configure'
initial values for variables by setting them in the environment.  Using
a Bourne-compatible shell, you can do that on the command line like
this:
     CC=c89 CFLAGS=-O2 LIBS=-lposix ./configure

Or on systems that have the `env' program, you can do it like this:
     env CPPFLAGS=-I/usr/local/include LDFLAGS=-s ./configure

Compiling For Multiple Architectures
====================================

   You can compile the package for more than one kind of computer at the
same time, by placing the object files for each architecture in their
own directory.  To do this, you must use a version of `make' that
supports the `VPATH' variable, such as GNU `make'.  `cd' to the
directory where you want the object files and executables to go and run
the `configure' script.  `configure' automatically checks for the
source code in the directory that `configure' is in and in `..'.

   If you have to use a `make' that does not supports the `VPATH'
variable, you have to compile the package for one architecture at a time
in the source code directory.  After you have installed the package for
one architecture, use `make distclean' before reconfiguring for another
architecture.

Installation Names
==================

   By default, `make install' will install the package's files in
`/usr/local/bin', `/usr/local/man', etc.  You can specify an
installation prefix other than `/usr/local' by giving `configure' the
option `--prefix=PATH'.

   You can specify separate installation prefixes for
architecture-specific files and architecture-independent files.  If you
give `configure' the option `--exec-prefix=PATH', the package will use
PATH as the prefix for installing programs and libraries.
Documentation and other data files will still use the regular prefix.

   In addition, if you use an unusual directory layout you can give
options like `--bindir=PATH' to specify different values for particular
kinds of files.  Run `configure --help' for a list of the directories
you can set and what kinds of files go in them.

   If the package supports it, you can cause programs to be installed
with an extra prefix or suffix on their names by giving `configure' the
option `--program-prefix=PREFIX' or `--program-suffix=SUFFIX'.

Optional Features
=================

   Some packages pay attention to `--enable-FEATURE' options to
`configure', where FEATURE indicates an optional part of the package.
They may also pay attention to `--with-PACKAGE' options, where PACKAGE
is something like `gnu-as' or `x' (for the X Window System).  The
`README' should mention any `--enable-' and `--with-' options that the
package recognizes.

   For packages that use the X Window System, `configure' can usually
find the X include and library files automatically, but if it doesn't,
you can use the `configure' options `--x-includes=DIR' and
`--x-libraries=DIR' to specify their locations.

Specifying the System Type
==========================

   There may be some features `configure' can not figure out
automatically, but needs to determine by the type of host the package
will run on.  Usually `configure' can figure that out, but if it prints
a message saying it can not guess the host type, give it the
`--host=TYPE' option.  TYPE can either be a short name for the system
type, such as `sun4', or a canonical name with three fields:
     CPU-COMPANY-SYSTEM

See the file `config.sub' for the possible values of each field.  If
`config.sub' isn't included in this package, then this package doesn't
need to know the host type.

   If you are building compiler tools for cross-compiling, you can also
use the `--target=TYPE' option to select the type of system they will
produce code for and the `--build=TYPE' option to select the type of
system on which you are compiling the package.

Sharing Defaults
================

   If you want to set default values for `configure' scripts to share,
you can create a site shell script called `config.site' that gives
default values for variables like `CC', `cache_file', and `prefix'.
`configure' looks for `PREFIX/share/config.site' if it exists, then
`PREFIX/etc/config.site' if it exists.  Or, you can set the
`CONFIG_SITE' environment variable to the location of the site script.
A warning: not all `configure' scripts look for a site script.

Operation Controls
==================

   `configure' recognizes the following options to control how it
operates.

`--cache-file=FILE'
     Use and save the results of the tests in FILE instead of
     `./config.cache'.  Set FILE to `/dev/null' to disable caching, for
     debugging `configure'.

`--help'
     Print a summary of the options to `configure', and exit.

`--quiet'
`--silent'
`-q'
     Do not print messages saying which checks are being made.  To
     suppress all normal output, redirect it to `/dev/null' (any error
     messages will still be shown).

`--srcdir=DIR'
     Look for the package's source code in directory DIR.  Usually
     `configure' can determine that directory automatically.

`--version'
     Print the version of Autoconf used to generate the `configure'
     script, and exit.

`configure' also accepts some other, not widely useful, options.



K. OpenLDAP Software Copyright Notices
======================================

K.1. OpenLDAP Copyright Notice
------------------------------

Copyright 1998-2013 The OpenLDAP Foundation.
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted only as authorized by the OpenLDAP Public
License.

A copy of this license is available in file LICENSE in the top-level
directory of the distribution or, alternatively, at
<http://www.OpenLDAP.org/license.html>.

OpenLDAP is a registered trademark of the OpenLDAP Foundation.

Individual files and/or contributed packages may be copyright by other
parties and their use subject to additional restrictions.

This work is derived from the University of Michigan LDAP v3.3
distribution.  Information concerning this software is available at
<http://www.umich.edu/~dirsvcs/ldap/ldap.html>.

This work also contains materials derived from public sources.

Additional information about OpenLDAP software can be obtained at
<http://www.OpenLDAP.org/>.

K.2. Additional Copyright Notices
---------------------------------

Portions Copyright 1998-2013 Kurt D. Zeilenga.
Portions Copyright
1998-2006 Net Boolean Incorporated.
Portions Copyright 2001-2006 IBM
Corporation.
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted only as authorized by the OpenLDAP Public
License.

Portions Copyright 1999-2008 Howard Y.H. Chu.
Portions Copyright
1999-2008 Symas Corporation.
Portions Copyright 1998-2003 Hallvard B.
Furuseth.
Portions Copyright 2007-2011 Gavin Henry.
Portions Copyright
2007-2011 Suretec Systems Limited.
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that this notice is preserved.
The names of the copyright holders may not be used to endorse or
promote products derived from this software without their specific
prior written permission.  This software is provided ``as is'' without
express or implied warranty.

K.3. University of Michigan Copyright Notice
--------------------------------------------

Portions Copyright 1992-1996 Regents of the University of
Michigan.
All rights reserved.

Redistribution and use in source and binary forms are permitted
provided that this notice is preserved and that due credit is given to
the University of Michigan at Ann Arbor. The name of the University
may not be used to endorse or promote products derived from this
software without specific prior written permission. This software is
provided ``as is'' without express or implied warranty.


L. OpenLDAP Public License
==========================

The OpenLDAP Public License
  Version 2.8, 17 August 2003

Redistribution and use of this software and associated documentation
("Software"), with or without modification, are permitted provided
that the following conditions are met:

1. Redistributions in source form must retain copyright statements
   and notices,

2. Redistributions in binary form must reproduce applicable copyright
   statements and notices, this list of conditions, and the following
   disclaimer in the documentation and/or other materials provided
   with the distribution, and

3. Redistributions must contain a verbatim copy of this document.

The OpenLDAP Foundation may revise this license from time to time.
Each revision is distinguished by a version number.  You may use
this Software under terms of this license revision or under the
terms of any subsequent revision of the license.

THIS SOFTWARE IS PROVIDED BY THE OPENLDAP FOUNDATION AND ITS
CONTRIBUTORS ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT
SHALL THE OPENLDAP FOUNDATION, ITS CONTRIBUTORS, OR THE AUTHOR(S)
OR OWNER(S) OF THE SOFTWARE BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.

The names of the authors and copyright holders must not be used in
advertising or otherwise to promote the sale, use or other dealing
in this Software without specific, written prior permission.  Title
to copyright in this Software shall at all times remain with copyright
holders.

OpenLDAP is a registered trademark of the OpenLDAP Foundation.

Copyright 1999-2003 The OpenLDAP Foundation, Redwood City,
California, USA.  All Rights Reserved.  Permission to copy and
distribute verbatim copies of this document is granted.

