Welcome to the Red Hat Directory Server Schema Reference. Red Hat Directory Server is a powerful and scalable distributed directory server application that uses the Lightweight Directory Access Protocol (LDAP) standard. Directory Server creates centralized and distributed data repositories for use with an intranet, extranet, and Internet applications. Integrating Directory Server into a computing infrastructure smooths interactions and services for customers, clients, and employees.
The Directory Server Schema Reference describes most of the common object classes and attributes defined by standard Directory Server schema. This reference is intended for system administrators who manage and maintain Red Hat Directory Server and define the directory schema.

1. Purpose and Contents

The schema reference covers information about attributes and object classes used by entries in the Directory Server:
  • An overview of some of the basic concepts of the directory schema, including lists and descriptions of default schema files, and descriptions of object classes, attributes, object identifiers (OIDs), schema checking, and extending server schema.
  • Alphabetical lists of the standard attributes, with definitions of their use, OIDs, and attribute syntax.
  • Alphabetical lists of the standard object classes with descriptions of the object class, OIDs, and lists of required and allowed attributes. (The defined attributes for the object classes do not include the required and allowed attributes which are inherited from any superior object classes.)
  • Directory Server's operational attributes and special attributes and object classes used by the server as part of its configuration, to perform tasks, or to manage databases.
This guide is intended as a reference for schema elements that are used to describe directory entries, like users, groups, and equipment, and some schema elements that are used to organize data in the directory, like views and roles.
However, this schema reference does not cover core schema used to configure the Directory Server itself. The directory service is also configured as directory entries within the cn=config subtree. For descriptions of those attributes, see the Configuration, Command, and File Reference.

2. Prerequisite Reading

This guide is a reference covering the standard schema and the standard object classes and attributes. However, this guide does not describe how to design, customize or maintain the schema, nor does it give any information on replication. Those concepts are described in the Deployment Guide. Read that book before continuing with this manual.
Preliminary planning for your schema needs depends on deciding how to represent the data which will be stored in the directory and the kinds of identities — different people, equipment, and facilities — which will be represented. Chose predefined schema elements to meet as many of the data needs as possible. These predefined schema elements are listed in this guide. After fully utilizing the standard schema, then begin planning how to extend the schema.

3. Examples and Formatting

Each of the examples used in this guide, such as file locations and commands, have certain defined conventions.

3.1. Command and File Examples

All of the examples for Red Hat Directory Server commands, file locations, and other usage are given for Red Hat Enterprise Linux 5 (64-bit) systems. Be certain to use the appropriate commands and files for your platform.

Example 1. Example Command

To start the Red Hat Directory Server:
service dirsrv start

3.2. Tool Locations

The tools for Red Hat Directory Server are located in the /usr/bin and the /usr/sbin directories. These tools can be run from any location without specifying the tool location.

3.3. LDAP Locations

There is an important consideration with the Red Hat Directory Server tools. The LDAP tools referenced in this guide are Mozilla LDAP, installed with Red Hat Directory Server in the /usr/lib64/mozldap directory on Red Hat Enterprise Linux 5 (64-bit) (or /usr/lib/mozldap for Red Hat Enterprise Linux 5 (32-bit) systems).
However, Red Hat Enterprise Linux systems also include LDAP tools from OpenLDAP in the /usr/bin directory. It is possible to use the OpenLDAP commands as shown in the examples, but you must use the -x argument to disable SASL, which OpenLDAP tools use by default.

3.4. Text Formatting and Styles

Certain words are represented in different fonts, styles, and weights. Different character formatting is used to indicate the function or purpose of the phrase being highlighted.
Formatting Style Purpose
Monospace font Monospace is used for commands, package names, files and directory paths, and any text displayed in a prompt.
with a
This type of formatting is used for anything entered or returned in a command prompt.
Italicized text Any text which is italicized is a variable, such as instance_name or hostname. Occasionally, this is also used to emphasize a new term or other phrase.
Bolded text Most phrases which are in bold are application names, such as Cygwin, or are fields or options in a user interface, such as a User Name Here: field or Save button.
Other formatting styles draw attention to important text.


A note provides additional information that can help illustrate the behavior of the system or provide more detail for a specific issue.


Important information is necessary, but possibly unexpected, such as a configuration change that will not persist after a reboot.


A warning indicates potential data loss, as may happen when tuning hardware for maximum performance.

4. Additional Reading

The Directory Server Administrator's Guide describes how to set up, configure, and administer Red Hat Directory Server and its contents. this manual does not describe many of the basic directory and architectural concepts that you need to deploy, install, and administer a directory service successfully. Those concepts are contained in the Red Hat Directory Server Deployment Guide. You should read that book before continuing with this manual.
When you are familiar with Directory Server concepts and have done some preliminary planning for your directory service, install the Directory Server. The instructions for installing the various Directory Server components are contained in the Red Hat Directory Server Installation Guide. Many of the scripts and commands used to install and administer the Directory Server are explained in detail in the Red Hat Directory Server Configuration, Command, and File Reference.
Also, Managing Servers with Red Hat Console contains general background information on how to use the Red Hat Console. You should read and understand the concepts in that book before you attempt to administer Directory Server.
The document set for Directory Server contains the following guides:
  • Red Hat Directory Server Release Notes contain important information on new features, fixed bugs, known issues and workarounds, and other important deployment information for this specific version of Directory Server.
  • Red Hat Directory Server Deployment Guide provides an overview for planning a deployment of the Directory Server.
  • Red Hat Directory Server Administrator's Guide contains procedures for the day-to-day maintenance of the directory service. Includes information on configuring server-side plug-ins.
  • Red Hat Directory Server Configuration, Command, and File Reference provides reference information on the command-line scripts, configuration attributes, and log files shipped with Directory Server.
  • Red Hat Directory Server Installation Guide contains procedures for installing your Directory Server as well as procedures for migrating from a previous installation of Directory Server.
  • Red Hat Directory Server Schema Reference provides reference information about the Directory Server schema.
  • Red Hat Directory Server Plug-in Programmer's Guide describes how to write server plug-ins in order to customize and extend the capabilities of Directory Server.
  • Using Red Hat Console gives an overview of the primary user interface and how it interacts with the Directory Server and Admin Server, as well as how to perform basic management tasks through the main Console window.
  • Using the Admin Server describes the different tasks and tools associated with the Admin Server and how to use the Admin Server with the Configuration and User Directory Server instances.
For the latest information about Directory Server, including current release notes, complete product documentation, technical notes, and deployment information, see the Red Hat Directory Server documentation site at

5. Giving Feedback

If there is any error in this Schema Reference or there is any way to improve the documentation, please let us know. Bugs can be filed against the documentation for Red Hat Directory Server through Bugzilla, Make the bug report as specific as possible, so we can be more effective in correcting any issues:
  1. Select the Red Hat Directory Server product.
  2. Set the component to Doc - schema-reference.
  3. Set the version number to 8.2.
  4. For errors, give the page number (for the PDF) or URL (for the HTML), and give a succinct description of the problem, such as incorrect procedure or typo.
    For enhancements, put in what information needs to be added and why.
  5. Give a clear title for the bug. For example, "Incorrect command example for setup script options" is better than "Bad example".
We appreciate receiving any feedback — requests for new sections, corrections, improvements, enhancements, even new ways of delivering the documentation or new styles of docs. You are welcome to contact Red Hat Content Services directly at

6. Documentation History

Revision History
Revision 8.2.1-1.4002013-10-31Rüdiger Landmann
Rebuild with publican 4.0.0
Revision 8.2.1-12012-07-18Anthony Towns
Rebuild for Publican 3.0
Revision 8.2-1January 6, 2011Ella Deon Lackey
Fixing typos, Bugzilla 662863.
Revision 8.2-0August 2, 2010Ella Deon Lackey
Initial draft for Red Hat Directory Server version 8.2.