(PAM) The new industry standard integrated login framework. PAM is used by system entry components, such as the Common Desktop Environment's dtlogin, to authenticate users logging into a Unix system. It provides pluggability for a variety of system-entry services. PAM's ability to stack authentication modules can be used to integrate login with different authentication mechanisms such as RSA, DCE and Kerberos, and thus unify login mechanisms. PAM can also integrate smart card authentication.

White paper.

[OSF-RFC 86.0 V. Samar, R. Schemers, "Unified Login with Pluggable Authentication Modules (PAM)", Oct 1995].