|Red Hat Enterprise Linux 4: Reference Guide
|Chapter 16. Pluggable Authentication Modules (PAM)
The directory /etc/pam.d/ contains the PAM configuration files for each PAM-aware application. In earlier versions of PAM, the file /etc/pam.conf was used, but this file is now deprecated and is only used if the /etc/pam.d/ directory does not exist.
Each PAM-aware application or service has a file within the /etc/pam.d/ directory. Each file within this directory bears the name of the service for which it controls access.
It is up to the PAM-aware program to define its service name and install its own PAM configuration file in the /etc/pam.d/ directory. For example, the login program defines its service name as login and installs the /etc/pam.d/login PAM configuration file.