PAM for Debian
PAM (Pluggable Authentication Modules) provides system administrators with a
powerful method of controlling system access and methods of authentication.
The documentation for PAM is packaged in the "libpam-doc" package. The
"Linux-PAM System Administrator's Guide" covers configuring PAM, what
modules are available etc. The documentation also includes "The Linux-PAM
Application Developers' Guide" and "The Linux-PAM Module Writers' Guide".
The Debian default configuration is to emulate the old UNIX authentication.