Centralized Logins Using LDAP and RADIUS
In This Chapter
The LDAP Directory Structure Scenario Downloading and Installing the LDAP Packages Configuring the LDAP Server Configuring the LDAP Client Configuring Encrypted LDAP Communication Troubleshooting LDAP Logins Common LDAP Administrative Tasks Configuring RADIUS for LDAP Conclusion
Many centralized database programs have been developed to allow users to log in on multiple computers using a single password. NIS was one of the first, but it doesn't encrypt the password transaction. It also uses the portmapper daemon, which uses an unpredictable range of TCP ports that are difficult for firewalls to track. LDAP (Lightweight Directory Access Protocol) provides an alternative based on the X.500 standard.
The X.500 standard defines how globally referenced directories of people should be structured. X.500 directories are organized under a common root directory in a tree hierarchy with different levels for each category of information, such as country, state, city, organization, organizational unit, and person. Designed to provide a simpler yet robust implementation of X.500, LDAP was originally used as the backbone of Microsoft's Active Directory Service and Novell's Novell Directory Services (NDS) products. LDAP can also interact with other login programs, such as Remote Authentication Dial-in User Service (RADIUS), which the network equipment of many ISPs use to manage dialup Internet access.
It was later recognized that LDAP had features that could make it a desirable replacement for NIS in some scenarios. For example, it uses a single TCP port (389) for regular communication and another port (636) for encrypted transactions. LDAP also can interact with many login authentication, authorization, and accounting programs external to Linux and UNIX.
This chapter will first show you how to install and use LDAP on Fedora Linux systems, then go on to explain how LDAP interacts with RADIUS.
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