This chapter outlines the problem and the roots of complexity of authentication, and discusses how the framework of Pluggable Authentication Modules (PAM) can provide solutions and reduce the complexity. This chapter also discusses installing Linux PAM: downloading its packages as well as compiling them. A brief introduction about extra PAM modules is provided at the end.
PAM is a concept and a framework. It can be implemented in many different ways, for example, PAM for Solaris, GNU/Linux, and FreeBSD/NetBSD are implemented independently. Even among the GNU/Linux distributions we see differences due to different versions. PAM bridges the UNX operating systems since PAM implementations are very similar. This book may be focused on GNU/Linux, but you should be able to apply the concepts to your favorite UNIX operating system.