PAM (Pluggable Authentication Modules) provides the backbone of most authentication in modern Linux systems (and can be implemented in others, such as Solaris), yet it is typically ignored and woefully under-utilized. Anytime you log into a modern Linux system, whether via telnet, ssh, pop, ftp, and so on, you are using PAM to process the authentication request. Anytime you need to authenticate to change your password (passwd), or login shell (chsh), you are talking to PAM.
News: Host Security
