Configuring Linux to Use LDAP for Login Authentication
At this point, your LDAP server should be running and should contain account information for your site. In order to do any good, though, you must be able to use that LDAP server for user authentication. In the case of Linux systems, this entails configuring the Pluggable Authentication Modules system and the Name Service Switch system to interface with LDAP. This requires understanding the basic relationships between these systems, installing necessary modules, and configuring the modules.
To use Windows as an LDAP login client, consult the Section 8.5.
LDAP, PAM, and NSS
The PAM and NSS systems are at the core of Linux’s account management. These systems are described in Chapter 7 and in Appendix A. In brief, PAM is a set of libraries that sits between applications and the account database for authentication purposes. Instead of accessing account databases directly, PAM-enabled applications consult PAM. This arrangement enables you to modify your authentication system (such as adding LDAP) with relative ease, by reconfiguring PAM rather than rewriting all the programs that require authentication. Similarly, NSS manages access to nonauthentication account information, such as home directory locations.
In order to configure a Linux system to use LDAP, you must tie LDAP into these two systems. This is done by installing PAM and NSS support modules and by modifying PAM and NSS configuration files to call the LDAP modules.