OpenLDAP Software 2.3 Administrator's Guide

The OpenLDAP Project <http://www.openldap.org/>
23 March 2005


Table of Contents


Preface

Copyright

Copyright 1998-2005, 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 B and C, respectively.

Scope of this Document

This document provides a guide for installing OpenLDAP Software 2.3 (http://www.openldap.org/software/) on UNIX (and UNIX-like) systems. The document is aimed at experienced system administrators but who may not have prior experience operating LDAP-based directory software.

This document is meant to be used in conjunction with other OpenLDAP information resources provided with the software package and on the project's extensive 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/
Software Pages http://www.OpenLDAP.org/software/
Support Pages http://www.OpenLDAP.org/support/

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 for building the foundation of LDAP software and information to which OpenLDAP Software is built upon. This document is based upon U-Mich LDAP 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 (http://search.cpan.org/src/IANC/sdf-2.001/doc/) documentation system developed by Ian Clatworthy. Tools for SDF are available from CPAN (http://search.cpan.org/search?query=SDF).


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 stand-alone LDAP daemon, slapd(8) and the stand-alone LDAP update replication daemon, slurpd(8). It is intended for newcomers and experienced administrators alike. This section provides a basic introduction to directory services and, in particular, the directory services provided by slapd(8).

1.1. What is a directory service?

A directory is a specialized database optimized for reading, browsing and searching. 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 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 replicas may be okay, as long as they get in sync eventually.

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. The Internet Domain Name System (DNS) is an example of a globally distributed directory 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. The nitty-gritty details of LDAP are defined in RFC2251 "The Lightweight Directory Access Protocol (v3)" and other documents comprising the technical specification RFC3377. 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 "[email?protected]". 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.

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.

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 RFC2253, "Lightweight Directory Access Protocol (v3): UTF-8 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 privacy and integrity security services.

1.3. How does LDAP work?

LDAP directory service is based on 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, like LDAP.

1.4. 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 stand-alone 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. As a lightweight directory server, slapd(8) implements only a subset of the 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 does not provide such a gateway, but our replication daemon can be used to replicate to such a gateway. See the Replication with slurpd chapter of this document for information regarding replication.

1.5. 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:

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

1.6. 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 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 provides privacy and integrity protections through the use of TLS (or SSL). slapd's TLS implementation utilizes OpenSSL 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 BDB, a high-performance transactional database backend; LDBM, a lightweight DBM based backend; SHELL, a backend interface to arbitrary shell scripts; and PASSWD, a simple backend interface to the passwd(5) file. The BDB backend utilizes Sleepycat Berkeley DB. The LDBM utilizes either Berkeley DB or GDBM.

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, shell, SQL, and TCL).

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-master/multiple-slave replication scheme is vital in high-volume environments where a single slapd just doesn't provide the necessary availability or reliability. slapd also includes experimental support for multi-master replication (for use where strong ACID properties are not required). slapd supports two replication methods: LDAP Sync-based and slurpd(8)-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.

1.7. What is slurpd and what can it do?

slurpd(8) is a daemon that, with slapd help, provides replicated service. It is responsible for distributing changes made to the master slapd database out to the various slapd replicas. It frees slapd from having to worry that some replicas might be down or unreachable when a change comes through; slurpd handles retrying failed requests automatically. slapd and slurpd communicate through a simple text file that is used to log changes.

See the Replication with slurpd chapter for information about how to configure and run slurpd(8).

Alternatively, LDAP-Sync-based replication may be used to provide a replicated service. See the LDAP Sync Replication chapter for details.


2. A Quick-Start Guide

The following is a quick start guide to OpenLDAP Software 2.3, including the stand-alone 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 (in particular, the OpenLDAP Software FAQ).

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 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 FAQ Installation Section (http://www.openldap.org/faq/ 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.conf(5) example (usually installed as /usr/local/etc/openldap/slapd.conf) to contain a BDB database definition of the form:
      database bdb
      suffix "dc=,dc="
      rootdn "cn=Manager,dc=,dc="
      rootpw secret
      directory /usr/local/var/openldap-data

    Be sure to replace and with the appropriate domain components of your domain name. For example, for example.com, use:
      database bdb
      suffix "dc=example,dc=com"
      rootdn "cn=Manager,dc=example,dc=com"
      rootpw secret
      directory /usr/local/var/openldap-data

    If your domain contains additional components, such as eng.uni.edu.eu, use:
      database bdb
      suffix "dc=eng,dc=uni,dc=edu,dc=eu"
      rootdn "cn=Manager,dc=eng,dc=uni,dc=edu,dc=eu"
      rootpw secret
      directory /usr/local/var/openldap-data

    Details regarding configuring slapd(8) can be found in the slapd.conf(5) manual page and the The slapd Configuration File chapter of this document. Note that the specified directory must exist prior to starting slapd(8).
    ?
  9. Start SLAPD.
    You are now ready to start the stand-alone LDAP server, slapd(8), by running the command:
      su root -c /usr/local/libexec/slapd

    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.
    ?
  10. 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=,dc=
      objectclass: dcObject
      objectclass: organization
      o:
      dc:

      dn: cn=Manager,dc=,dc=
      objectclass: organizationalRole
      cn: Manager

    Be sure to replace and with the appropriate domain components of your domain name. 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=,dc=" -W -f example.ldif

    Be sure to replace and 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.
    ?
  11. 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 section of The slapd Configuration File 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 stand-alone LDAP server slapd(8) fits in with the rest of the world.

3.1. Local Directory Service

In this configuration, you run a slapd 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.

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 which provides directory service for your local domain and configure it to return referrals to a superior service capable of handling requests outside your local domain. You may run this service yourself or use one provided to you. This configuration is shown in Figure 3.2.

Figure 3.2: Local service with referrals

Use this configuration if you want to provide local service and participate in the Global Directory.

3.3. Replicated Directory Service

The slurpd daemon is used to propagate changes from a master slapd to one or more slave slapds. An example master-slave configuration is shown in figure 3.3.

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 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 stand-alone LDAP daemon and slurpd(8), the stand-alone update replication 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 stablity 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:

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 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 often requires separate installation.

OpenSSL is available from http://www.openssl.org/.

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

4.2.2. Kerberos Authentication Services

OpenLDAP clients and servers support Kerberos-based authentication services. In particular, OpenLDAP supports the SASL/GSSAPI authentication mechanism using either Heimdal or MIT Kerberos V packages. If you desire to use Kerberos-based SASL/GSSAPI authentication, you should install either Heimdal or MIT Kerberos V.

Heimdal Kerberos is available from http://www.pdc.kth.se/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.

4.2.3. Simple Authentication and Security Layer

OpenLDAP clients and servers require installation of Cyrus's 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.

4.2.4. Database Software

OpenLDAP's slapd(8) primary database backend, BDB, requires Sleepycat Software Berkeley DB. If not available at configure time, you will not be able build slapd(8) with this primary database backend.

Your operating system may provide a supported version of Berkeley DB in the base system or as an optional software component. If not, you'll have to obtain and install it yourself.

Berkeley DB is available from Sleepycat Software's download page http://www.sleepycat.com/download/. There are several versions available. Generally, the most recent release (with published patches) is recommended. This package is required if you wish to use the BDB database backend.

OpenLDAP's slapd(8) LDBM backend supports a variety of data base managers including Berkeley DB and GDBM. GDBM is available from FSF's download site ftp://ftp.gnu.org/pub/gnu/gdbm/.

4.2.5. Threads

OpenLDAP is designed to take advantage of threads. OpenLDAP supports POSIX pthreads, Mach CThreads, 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 will also look at various environment variables for certain settings. These environment variables include:

Table 4.1: Environment 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 environment variables.

        [[env] settings] ./configure [options]

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

        ./configure --with-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 be called as follows:

        env CPPFLAGS="-I/usr/local/include" LDFLAGS="-L/usr/local/lib" \
                ./configure --with-wrappers


Note: Some shells, such as those derived from the Bourne sh(1), do not require use of the env(1) command. In some cases, environmental variables have to be specified using alternative syntaxes.

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) and slurpd(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 The slapd Configuration File for additional information.


5. The slapd Configuration File

Once the software has been built and installed, you are ready to configure slapd(8) for use at your site. The slapd runtime configuration is primarily accomplished through the slapd.conf(5) file, normally installed in the /usr/local/etc/openldap directory.

An alternate configuration file can be specified via a command-line option to slapd(8) or slurpd(8). This chapter describes the general format of the config file, followed by a detailed description of commonly used config file directives.

5.1. 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 white space, 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
        

        # backend definition
        backend 
        

        # first database definition & config directives
        database 
        

        # second database definition & config directives
        database 
        

        # second database definition & config directives
        database 
        

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

A configuration directive may take arguments. If so, they are separated by white space. If an argument contains white space, 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.

5.2. 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.

5.2.1. 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 <>.

5.2.1.1. access to [ by ]+

This directive grants access (specified by ) to a set of entries and/or attributes (specified by ) by one or more requesters (specified by ). See the Access Control section of this chapter for a summary of 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.

5.2.1.2. attributetype <RFC2252 Attribute Type Description>

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

5.2.1.3. idletimeout

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

5.2.1.4. include

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.

5.2.1.5. loglevel

This directive specifies the level at which debugging statements and operation statistics should be syslogged (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 are additive. To display what numbers correspond to what kind of debugging, invoke slapd with -? or consult the table below. The possible values for are:

Table 5.1: Debugging Levels
Level Description
-1 enable all debugging
0 no debugging
1 trace function calls
2 debug packet handling
4 heavy trace debugging
8 connection management
16 print out packets sent and received
32 search filter processing
64 configuration file processing
128 access control list processing
256 stats log connections/operations/results
512 stats log entries sent
1024 print communication with shell backends
2048 print entry parsing debugging

Example:

 loglevel -1

This will cause lots and lots of debugging information to be logged.

Default:

 loglevel 256

5.2.1.6. objectclass <RFC2252 Object Class Description>

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

5.2.1.7. referral

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.

5.2.1.8. sizelimit

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

Default:

        sizelimit 500

5.2.1.9. timelimit

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

5.2.2. 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.

5.2.2.1. backend

This directive marks the beginning of a backend declaration. should be one of the supported backend types listed in Table 5.2.

Table 5.2: Database Backends
Types Description
bdb Berkeley DB transactional backend
dnssrv DNS SRV backend
ldap Lightweight Directory Access Protocol (Proxy) backend
ldbm Lightweight DBM backend
meta Meta Directory backend
monitor Monitor backend
passwd Provides read-only access to passwd(5)
perl Perl Programmable backend
shell Shell (extern program) backend
sql SQL Programmable backend

Example:

        backend bdb

This marks the beginning of a new BDB backend definition.

5.2.3. 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.

5.2.3.1. database

This directive marks the beginning of a database instance declaration. should be one of the supported backend types listed in Table 5.2.

Example:

        database bdb

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

5.2.3.2. 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.

Default:

        readonly off

5.2.3.3. replica

        replica uri=ldap[s]://[:] | host=[:]
                [bindmethod={simple|kerberos|sasl}]
                ["binddn="]
                [saslmech=]
                [authcid=]
                [authzid=]
                [credentials=]
                [srvtab=]

This directive specifies a replication site for this database. The uri= parameter specifies a scheme, a host and optionally a port where the slave slapd instance can be found. Either a domain name or IP address may be used for . If is not given, the standard LDAP port number (389 or 636) is used.

host is deprecated in favor of the uri parameter.

uri allows the replica LDAP server to be specified as an LDAP URI such as ldap://slave.example.com:389 or ldaps://slave.example.com:636.

The binddn= parameter gives the DN to bind as for updates to the slave slapd. It should be a DN which has read/write access to the slave slapd's database. It must also match the updatedn directive in the slave slapd's config file. Generally, this DN should not be the same as the rootdn of the master database. Since DNs are likely to contain embedded spaces, the entire "binddn=" string should be enclosed in double quotes.

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

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

Kerberos authentication is deprecated in favor of SASL authentication mechanisms, in particular the KERBEROS_V4 and GSSAPI mechanisms. Kerberos authentication requires binddn and srvtab 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.

See the chapter entitled Replication with slurpd for more information on how to use this directive.

5.2.3.4. replogfile

This directive specifies the name of the replication log file to which slapd will log changes. The replication log is typically written by slapd and read by slurpd. Normally, this directive is only used if slurpd is being used to replicate the database. However, you can also use it to generate a transaction log, if slurpd is not running. In this case, you will need to periodically truncate the file, since it will grow indefinitely otherwise.

See the chapter entitled Replication with slurpd for more information on how to use this directive.

5.2.3.5. rootdn

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.

5.2.3.6. rootpw

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 RFC 2307 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.

5.2.3.7. 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.

5.2.3.8. syncrepl

        syncrepl rid=
                provider=ldap[s]://[:port]
                [type=refreshOnly|refreshAndPersist]
                [interval=dd:hh:mm:ss]
                [retry=[ <# of retries>]+]
                [searchbase=]
                [filter=]
                [scope=sub|one|base]
                [attrs=]
                [attrsonly]
                [sizelimit=]
                [timelimit=]
                [schemachecking=on|off]
                [bindmethod=simple|sasl]
                [binddn=]
                [saslmech=]
                [authcid=]
                [authzid=]
                [credentials=]
                [realm=]
                [secprops=]

This directive specifies the current database as a replica of the master content by establishing the current slapd(8) as a replication consumer site running a syncrepl replication engine. The master database is located at the replication provider site specified by the provider parameter. The replica database is kept up-to-date with the master content using the LDAP Content Synchronization protocol. See draft-zeilenga-ldup-sync-xx.txt (a work in progress) for more information on the protocol.

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

The provider parameter specifies the replication provider site containing the master 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 . Examples are ldap://provider.example.com:389 or ldaps://192.168.1.1:636. If 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 at the consumer site, whereas the replica specification is located at the provider site. syncrepl and replica directives define two independent replication mechanisms. They do not represent the replication peers of each other.

The content of the syncrepl replica 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, attrsonly, sizelimit, and timelimit parameters as in the normal search specification. The syncrepl search specification has the same value syntax and the same default values as in the ldapsearch(1) client search tool.

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. Further updates to the master replica 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 and <# of retries> pairs. For example, retry="60 5 300 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 into the replica content. Every entry in the replica 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 master 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.

Simple authentication should not be used unless adequate integrity and privacy 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 syncrepl replication mechanism is supported by the three native backends: back-bdb, back-hdb, and back-ldbm.

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

5.2.3.9. updatedn

This directive is only applicable in a slave slapd. It specifies the DN allowed to make changes to the replica. This may be the DN slurpd(8) binds as when making changes to the replica or the DN associated with a SASL identity.

Entry-based Example:

        updatedn "cn=Update Daemon,dc=example,dc=com"

SASL-based Example:

        updatedn "uid=slurpd,cn=example.com,cn=digest-md5,cn=auth"

See the Replication with slurpd chapter for more information on how to use this directive.

5.2.3.10. updateref

This directive is only applicable in a slave slapd. 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://master.example.net

5.2.4. BDB Database Directives

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

5.2.4.1. directory

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

Default:

        directory /usr/local/var/openldap-data

5.2.5. LDBM Database Directives

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

5.2.5.1. cachesize

This directive specifies the size in entries of the in-memory cache maintained by the LDBM backend database instance.

Default:

        cachesize 1000

5.2.5.2. dbcachesize

This directive specifies the size in bytes of the in-memory cache associated with each open index file. If not supported by the underlying database method, this directive is ignored without comment. Increasing this number uses more memory but can cause a dramatic performance increase, especially during modifies or when building indices.

Default:

        dbcachesize 100000

5.2.5.3. dbnolocking

This option, if present, disables database locking. Enabling this option may improve performance at the expense of data security.

5.2.5.4. dbnosync

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

5.2.5.5. directory

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

Default:

        directory /usr/local/var/openldap-data

5.2.5.6. index { | default} [pres,eq,approx,sub,none]

This directive specifies the indices to maintain for the given attribute. If only an is given, the default indices are maintained.

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.

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

        index objectClass eq

5.2.5.7. mode

This directive specifies the file protection mode that newly created database index files should have.

Default:

        mode 0600

5.3. Access Control

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

         ::= access to 
                [by   ]+
         ::= * |
                [dn[.]= | dn.=]
                [filter=] [attrs=]
         ::= regex | exact
         ::= base | one | subtree | children
         ::=  [val[.]=] |  , 
         ::=  | entry | children
         ::= * | [anonymous | users | self
                        | dn[.]= | dn.=]
                [dnattr=]
                [group[/[/][.]]=]
                [peername[.]=]
                [sockname[.]=]
                [domain[.]=]
                [sockurl[.]=]
                [set=]
                [aci=]
         ::= [self]{|}
         ::= none | auth | compare | search | read | write
         ::= {=|+|-}{w|r|s|c|x|0}+
         ::= [stop | continue | break]

where the part selects the entries and/or attributes to which the access applies, the part specifies which entities are granted access, and the part specifies the access granted. Multiple 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.

5.3.1. What to control access to

The 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[.]=
        to 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 is a string representation of the Distinguished Name, as described in RFC2253.

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:

Entries may also be selected using a filter:

        to filter=

where is a string representation of an LDAP search filter, as described in RFC2254. For example:

        to filter=(objectClass=person)

Note that entries may be selected by both DN and filter by including both qualifiers in the 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 selector:

        attrs=

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

        attrs= val[.