I believe that knowing how to administer a Lightweight Directory Access Protocol (LDAP) directory server has become an essential skill for a network administrator. An LDAP directory is your key to network simplicity. It is your universal directory across all platforms and applications, supporting simplified network authentication and a centralized company data store. The LDAP protocol is cross-platform, network-aware, and standards-based. There are a large number of LDAP implementations; in this chapter, we’ll use the excellent free-of-cost, free-software OpenLDAP.
LDAP is widely supported by applications; for example, most email clients come with LDAP clients. Additionally, various databases, Content Management Systems (CMS), groupware and messaging servers, authentication servers, customer management applications, and application servers can all speak to an LDAP server.
Some folks like to argue about whether LDAP is a database. Strictly speaking, it is a protocol, not a database. It accesses a special kind of database that is optimized for very fast reads. Use it for relatively static information, such as company directories, user data, customer data, passwords, asset tracking, and security keys. OpenLDAP uses the Sleepycat Berkeley DB.
Why not use an ordinary relational database like PostgreSQL, Oracle, or MySQL? You can if you like, but then you’ll lose the advantages of LDAP, which are:
Very fast reads