PAM Configuration Files
The Each PAM-aware application or service has a file in the The PAM-aware program is responsible for defining its service name and installing its own PAM configuration file in the /etc/pam.d/ directory contains the PAM configuration files for each PAM-aware application. In earlier versions of PAM, the /etc/pam.conf file was used, but this file is now deprecated and is only used if the /etc/pam.d/ directory does not exist.
PAM Service Files
/etc/pam.d/ directory. Each file in this directory has the same name as the service to which it controls access.
/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.