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
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.
| 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
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
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
1.2. What is LDAP?
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
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
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. 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,
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 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
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:
- Strong authentication and data security services via
SASL - Certificate authentication and data security services via
TLS (SSL) - Internationalization through the use of Unicode
- Referrals and Continuations
- Schema Discovery
- 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, interoperatibility 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.
1.6. 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
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,
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
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
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 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
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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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).
- 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=<MY-DOMAIN>,dc=<COM>"
rootdn "cn=Manager,dc=<MY-DOMAIN>,dc=<COM>"
rootpw secret
directory /usr/local/var/openldap-data
Be sure to replace <MY-DOMAIN> and <COM> 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).
- 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.
- 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:- create an LDIF file
- 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.
- 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
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
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:
-
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
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
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
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)
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
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:
| 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 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. Unlike previous OpenLDAP releases, the slapd runtime configuration in 2.3 is fully LDAP-enabled and can be managed using the standard LDAP operations with data in
An alternate configuration directory (or file) can be specified via a command-line option to slapd(8) or slurpd(8). This chapter describes the general format of the configuration system, followed by a detailed description of commonly used config settings.
Note: some of the backends and of the distributed overlays do not support runtime configuration yet. In those cases, the old style slapd.conf(5) file must be used.
Note: the current version of slurpd has not been updated for compatibility with this new configuration engine. If you must use slurpd for replication at your site, you will have to maintain an old-style slapd.conf file for slurpd to use.
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.
Figure 5.1: Sample configuration tree.
Other objects may be part of the configuration but were omitted from the illustration for clarity.
The slapd.d 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:
- Include files
-
Usually these are just pathnames left over from a converted slapd.conf file.
Otherwise use of Include files is deprecated. - Dynamically loaded modules
-
These may only be used if the --enable-modules option was used to configure the software.
- 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. - Backend-specific configuration
- 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 white space. If an argument contains white space, 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.d(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 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 may be specified as integers or by keyword. Multiple log levels may be used and the levels are additive. To display what levels correspond to what kind of debugging, invoke slapd with -? or consult the table below. The possible values for <level> are:
| Level | Keyword | Description |
| -1 | Any | enable all debugging |
| 0 | no debugging | |
| 1 | Trace | trace function calls |
| 2 | Packets | debug packet handling |
| 4 | Args | heavy trace debugging |
| 8 | Conns | connection management |
| 16 | BER | print out packets sent and received |
| 32 | Filter | search filter processing |
| 64 | Config | configuration processing |
| 128 | ACL | access control list processing |
| 256 | Stats | stats log connections/operations/results |
| 512 | Stats2 | stats log entries sent |
| 1024 | Shell | print communication with shell backends |
| 2048 | Parse | print entry parsing debugging |
| 4096 | Cache | database cache processing |
| 8192 | Index | database indexing |
| 16384 | Sync | syncrepl consumer processing |
Example:
olcLogLevel: -1
This will cause lots and lots of debugging information to be logged.
olcLogLevel: Conns Filter
Just log the connection and search filter processing.
Default:
olcLogLevel: Stats
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=include
An include entry holds the pathname of one include file. Include files are part of the old style slapd.conf configuration system and must be in slapd.conf format. Include files were commonly used to load schema specifications. While they are still supported, their use is deprecated. Include entries must have the olcIncludeFile objectClass.
5.2.2.1. olcInclude: <filename>
This directive specifies that slapd should read additional configuration information from the given file.
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.
5.2.2.2. Sample Entries
dn: cn=include{0},cn=config
objectClass: olcIncludeFile
cn: include{0}
olcInclude: ./schema/core.schema
dn: cn=include{1},cn=config
objectClass: olcIncludeFile
cn: include{1}
olcInclude: ./schema/cosine.schema
5.2.3. 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.
5.2.3.1. 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.
5.2.3.2. 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.
5.2.3.3. 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
5.2.4. 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.
5.2.4.1. olcAttributeTypes: <RFC2252 Attribute Type Description>
This directive defines an attribute type. Please see the Schema Specification chapter for information regarding how to use this directive.
5.2.4.2. olcObjectClasses: <RFC2252 Object Class Description>
This directive defines an object class. Please see the Schema Specification chapter for information regarding how to use this directive.
5.2.4.3. 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 )
5.2.5. 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.
5.2.5.1. olcBackend: <type>
This directive names a backend-specific configuration entry. <type> should be one of the supported backend types listed in Table 5.2.
| Types | Description |
| bdb | Berkeley DB transactional backend |
| config | Slapd configuration backend |
| dnssrv | DNS SRV backend |
| hdb | Hierarchical variant of bdb backend |
| ldap | Lightweight Directory Access Protocol (Proxy) backend |
| ldbm | Lightweight DBM backend |
| ldif | Lightweight Data Interchange Format 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:
olcBackend: bdb
There are no other directives defined for this entry. Specific backend types may define additional attributes for their particular use but so far none have ever been defined. As such, these directives usually do not appear in any actual configurations.
5.2.5.2. Sample Entry
dn: olcBackend=bdb,cn=config objectClass: olcBackendConfig olcBackend: bdb
5.2.6. Database-specific Directives
Directives in this section are supported by every type of database. Database entries must have the olcDatabaseConfig objectClass.
5.2.6.1. 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: bdb
This marks the beginning of a new
5.2.6.2. 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 requesters (specified by <who>). See the Access Control section of this chapter for a summary of 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.
5.2.6.3. 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.
Default:
olcReadonly: FALSE
5.2.6.4. olcReplica
olcReplica: uri=ldap[s]://<hostname>[:<port>] | host=<hostname>[:<port>]
[bindmethod={simple|sasl}]
["binddn=<DN>"]
[saslmech=<mech>]
[authcid=<identity>]
[authzid=<identity>]
[credentials=<password>]
This directive specifies a replication site for this database for use with slurpd. 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 <hostname>. If <port> 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=<DN>" string should be enclosed in double quotes.
The bindmethod is simple or sasl, depending on whether simple password-based authentication or
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.
See the chapter entitled Replication with slurpd for more information on how to use this directive.
5.2.6.5. olcReplogfile: <filename>
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.
5.2.6.6. 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.
5.2.6.7. 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 RFC 2307 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.
5.2.6.8. olcSizeLimit: <integer>
This directive specifies the maximum number of entries to return from a search operation.
Default:
olcSizeLimit: 500
5.2.6.9. 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.
5.2.6.10. olcSyncrepl
olcSyncrepl: rid=<replica ID>
provider=ldap[s]://<hostname>[:port]
[starttls=yes|critical]
[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>]
[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>]
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 <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 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 <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 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 starttls parameter specifies use of the StartTLS extended operation to establish a TLS session before Binding to the provider. If the StartTLS request fails and the critical argument was used, the session will be aborted. Otherwise the syncrepl session continues without TLS.
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 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 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 <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 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
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 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.
5.2.6.11. 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
5.2.6.12. olcUpdateDN: <DN>
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:
olcUpdateDN: "cn=Update Daemon,dc=example,dc=com"
SASL-based Example:
olcUpdateDN: "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.
5.2.6.13. olcUpdateref: <URL>
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
Example:
olcUpdateref: ldap://master.example.net
5.2.6.14. 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
5.2.7. BDB and HDB Database Directives
Directives in this category apply to both the
5.2.7.1. olcDbDirectory: <directory>
This directive specifies the directory where the BDB files containing the database and associated indices live.
Default:
olcDbDirectory: /usr/local/var/openldap-data
5.2.7.2. olcDbCachesize: <integer>
This directive specifies the size in entries of the in-memory cache maintained by the BDB backend database instance.
Default:
olcDbCachesize: 1000
5.2.7.3. olcDbCheckpoint: <kbyte> <min>
This directive specifies how often to checkpoint the BDB transaction log. A checkpoint operation flushes the database buffers to disk and writes a checkpoint record in the log. The checkpoint will occur if either <kbyte> data has been written or <min> minutes have passed since the last checkpont. 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. See the Berkeley DB reference guide for more details.
Example:
olcDbCheckpoint: 1024 10
5.2.7.4. olcDbConfig: <DB_CONFIG setting>
This attribute specifies a configuration directive to be placed in the DB_CONFIG file of the database directory. At server startup time, if no such file exists yet, the DB_CONFIG file will be created and the settings in this attribute will be written to it. If the file exists, its contents will be read and displayed in this attribute. The attribute is multi-valued, to accomodate multiple configuration directives. No default is provided, but it is essential to use proper settings here to get the best server performance.
Example:
olcDbConfig: set_cachesize 0 10485760 0
olcDbConfig: set_lg_bsize 2097512
olcDbConfig: set_lg_dir /var/tmp/bdb-log
olcDbConfig: set_flags DB_LOG_AUTOREMOVE
In this example, the BDB cache is set to 10MB, the BDB transaction log buffer size is set to 2MB, and the transaction log files are to be stored in the /var/tmp/bdb-log directory. Also a flag is set to tell BDB to delete transaction log files as soon as their contents have been checkpointed and they are no longer needed. Without this setting the transaction log files will continue to accumulate until some other cleanup procedure removes them. See the SleepyCat documentation for the db_archive command for details.
Ideally the BDB cache must be at least as large as the working set of the database, the log buffer size should be large enough to accomodate most transactions without overflowing, and the log directory must be on a separate physical disk from the main database files. And both the database directory and the log directory should be separate from disks used for regular system activities such as the root, boot, or swap filesystems. See the FAQ-o-Matic and the SleepyCat documentation for more details.
5.2.7.5. olcDbNosync: { TRUE | FALSE }
This option 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. This directive has the same effect as using
olcDbConfig: set_flags DB_TXN_NOSYNC
5.2.7.6. olcDbIDLcacheSize: <integer>
Specify the size of the in-memory index cache, in index slots. The default is zero. A larger value will speed up frequent searches of indexed entries. The optimal size will depend on the data and search characteristics of the database, but using a number three times the entry cache size is a good starting point.
Example:
olcDbIDLcacheSize: 3000
5.2.7.7. 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.
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.
By default, no indices are maintained. It is generally advised that minimally an equality index upon objectClass be maintained.
olcDbindex: objectClass eq
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.
5.2.7.8. olcDbLinearIndex: { TRUE | FALSE }
If this setting is TRUE slapindex will index one attribute at a time. The default settings is FALSE in which case all indexed attributes of an entry are processed at the same time. When enabled, each indexed attribute is processed individually, using multiple passes through the entire database. This option improves slapindex performance when the database size exceeds the BDB cache size. When the BDB cache is large enough, this option is not needed and will decrease performance. Also by default, slapadd performs full indexing and so a separate slapindex run is not needed. With this option, slapadd does no indexing and slapindex must be used.
5.2.7.9. olcDbMode: <integer>
This directive specifies the file protection mode that newly created database index files should have.
Default:
olcDbMode: 0600
5.2.7.10. olcDbSearchStack: <integer>
Specify the depth of the stack used for search filter evaluation. Search filters are evaluated on a stack to accomodate 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
5.2.7.11. olcDbShmKey: <integer>
Specify a key for a shared memory BDB environment. By default the BDB environment uses memory mapped files. If a non-zero value is specified, it will be used as the key to identify a shared memory region that will house the environment.
Example:
olcDbShmKey: 42
5.2.7.12. Sample Entry
dn: olcDatabase=hdb,cn=config objectClass: olcDatabaseConfig objectClass: olcHdbConfig olcDatabase: hdb olcSuffix: "dc=example,dc=com" olcDbDirectory: /usr/local/var/openldap-data olcDbCacheSize: 1000 olcDbCheckpoint: 1024 10 olcDbConfig: set_cachesize 0 10485760 0 olcDbConfig: set_lg_bsize 2097152 olcDbConfig: set_lg_dir /var/tmp/bdb-log olcDbConfig: set_flags DB_LOG_AUTOREMOVE olcDbIDLcacheSize: 3000 olcDbIndex: objectClass eq
5.3. Access Control
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 | auth | compare | search | read | write
<priv> ::= {=|+|-}{w|r|s|c|x|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.
5.3.1. 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 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:
-
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 RFC2254. 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 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=.*"
5.3.2. 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:
| 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 spoofed, the domain factor should not be avoided.
5.3.3. The access to grant
The kind of <access> granted can be one of the following:
| Level | Privileges | Description |
| none | =0 | no access |
| auth | =x | needed to bind |
| compare | =cx | needed to compare |
| search | =scx | needed to apply search filters |
| read | =rscx | needed to read search results |
| write | =wrscx | needed to modify/rename |
Each level implies all lower levels of access. So, for example, granting someone write access to an entry also grants them read, search, compare, and auth access. However, one may use the privileges specifier to grant specific permissions.
5.3.4. 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 first database if not held in any database) apply first, followed by the global access directives (which are held in the frontend database definition). 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.
5.3.5. 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. That is, every olcAccess: to directive ends with an implicit by * none clause and every access list ends with an implicit olcAccess: to * by * none directive.
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.
5.3.6. 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.
5.4. Configuration Example
The following is an example configuration, interspersed with explanatory text. It defines two databases to handle different parts of the
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. olcDatabase: frontend 19. olcAccess: to * by * read 20.
Line 15 is a comment. Lines 16-18 identify this entry as the global database entry. Line 19 is a global access control. It applies to all entries (after any applicable database-specific access controls).
The next entry defines a BDB 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.
21. # BDB definition for example.com 22. dn: olcDatabase=bdb,cn=config 23. objectClass: olcDatabaseConfig 24. objectClass: olcBdbConfig 25. olcDatabase: bdb 26. olcSuffix: "dc=example,dc=com" 27. olcDbDirectory: /usr/local/var/openldap-data 28. olcRootDN: "cn=Manager,dc=example,dc=com" 29. olcRootPW: secret 30. olcDbIndex: uid pres,eq 31. olcDbIndex: cn,sn,uid pres,eq,approx,sub 32. olcDbIndex: objectClass eq 33. olcAccess: to attrs=userPassword 34. by self write 35. by anonymous auth 36. by dn.base="cn=Admin,dc=example,dc=com" write 37. by * none 38. olcAccess: to * 39. by self write 40. by dn.base="cn=Admin,dc=example,dc=com" write 41. by * read 42.
Line 21 is a comment. Lines 22-25 identify this entry as a BDB database configuration entry. Line 26 specifies the DN suffix for queries to pass to this database. Line 27 specifies the directory in which the database files will live.
Lines 28 and 29 identify the database super-user entry and associated password. This entry is not subject to access control or size or time limit restrictions.
Lines 30 through 32 indicate the indices to maintain for various attributes.
Lines 33 through 41 specify access control for entries in this database. As this is the first database, the controls also apply to entries not held in any database (such as the Root DSE). 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 42 is a blank line, indicating the end of this entry.
The next section of the example configuration file defines another BDB 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 51, the read access would be allowed due to the global access rule at line 19.
42. # BDB definition for example.net 43. dn: olcDatabase=bdb,cn=config 44. objectClass: olcDatabaseConfig 45. objectClass: olcBdbConfig 46. olcDatabase: bdb 47. olcSuffix: "dc=example,dc=net" 48. olcDbDirectory: /usr/local/var/openldap-data-net 49. olcRootDN: "cn=Manager,dc=example,dc=com" 50. olcDbIndex: objectClass eq 51. olcAccess: to * by users read
6. 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.
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 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
<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 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.
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 requesters (specified by <who>). 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.
6.2.1.2. 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.
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 <integer>
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 <integer> are:
| 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
6.2.1.6. 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.
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 LDA