PAM stands for Pluggable Authentication Modules and is a system for providing application independence for authentication. A PAM-enabled application calls a stack of PAM modules to run authentication, open and close sessions, and check account validity.. . .
PAM stands for Pluggable Authentication Modules and is a system for providing application independence for authentication. A PAM-enabled application calls a stack of PAM modules to run authentication, open and close sessions, and check account validity.

This is part three of a three-part series on writing PAM modules. Part one discussed the background information needed to write modules. Part two covered supporting code, including the conversation structure.

PAM modules are grouped into four module types, though there are six critical functions. Applications call each of the functions as they need them, but system administrators can only choose functions by their module type.