As current authentication mechanisms evolve and as new authentication mechanisms are introduced, system entry services such as login, rlogin, and telnet must continually be customized to incorporate these changes.
With the Pluggable Authentication Module (PAM) framework, multiple authentication technologies can be added without changing any of the login services, thereby preserving existing system environments. PAM can be used to integrate login services with different authentication technologies, such as RSA, DCE, Kerberos, S/Key, and smart card based authentication systems.
Thus, PAM enables networked machines to exist peacefully in a heterogeneous environment, where multiple security mechanisms are in place. The PAM framework and the module interfaces provide pluggability for user authentication, as well as for account, session, and password management. login and other system-entry services can use the PAM architecture, and thus ensure that