10.3.9.3. LDAP

The Lightweight Directory Access Protocol is a client-server system for accessing global or local directory services over a network. On Linux, the OpenLDAP implementation is used. It includes slapd, a stand-alone server; slurpd, a stand-alone LDAP replication server; libraries implementing the LDAP protocol and a series of utilities, tools and sample clients.

The main benefit of using LDAP is the consolidation of certain types of information within your organization. For example, all of the different lists of users within your organization can be merged into one LDAP directory. This directory can be queried by any LDAP-enabled applications that need this information. It can also be accessed by users who need directory information.

Other LDAP or X.500 Lite benefits include its ease of implementation (compared to X.500) and its well-defined Application Programming Interface (API), which means that the number of LDAP-enabled applications and LDAP gateways should increase in the future.

On the negative side, if you want to use LDAP, you will need LDAP-enabled applications or the ability to use LDAP gateways. While LDAP usage should only increase, currently there are not very many LDAP-enabled applications available for Linux. Also, while LDAP does support some access control, it does not possess as many security features as X.500.

Since LDAP is an open and configurable protocol, it can be used to store almost any type of information relating to a particular organizational structure. Common examples are mail address lookups, central authentication in combination with PAM, telephone directories and machine configuration databases.

See your system specific information and the man pages for related commands such as ldapmodify and ldapsearch for details. More information can be found in the LDAP Linux HOWTO, which discusses installation, configuration, running and maintenance of an LDAP server on Linux. The author of this Introduction to Linux document also wrote an LDAP Operations HOWTO, describing the basics everyone should know about when dealing with LDAP management, operations and integration of services.