Chapter 16. Pluggable Authentication Modules (PAM)
Programs which grant users access to a system verify each user's
identity through a process called
authentication. Historically, each such
program had its own way of performing the task of
authentication. Under Red Hat Enterprise Linux, many such programs are configured
to use a centralized authentication mechanism called
Pluggable Authentication Modules or
PAM.
PAM uses a pluggable, modular architecture, which affords the system
administrator a great deal of flexibility in setting authentication policies
for the system.
In most situations, the default PAM configuration file for a PAM-aware
application is sufficient. However, sometimes it may become necessary to
edit a PAM configuration file. Because misconfiguration of PAM can
compromise system security, it is important to understand the structure of
these files before making any modifications (refer to Section 16.3 PAM Configuration File Format for more information).
PAM offers the following advantages:
It provides a common authentication scheme that can be used
with a wide variety of applications.
It allows a large amount of flexibility and control over
authentication for both system administrators and application
developers.
It allows application developers to develop programs
without creating their own authentication scheme.
