Authentication

Authentication is a line of defense for networks and systems in Linux. The user authentication offers system security, which involves searching the user ID and group ID in the local repository.Linux systems mostly rely on username and password authentication, but some other authentications like smartcards and tokens are also available. Authentication is performed by the use of LDAP, Kerberos and Winbind.The SSH (Secure Shell) server and the NIS allows password authentication. PAM (Pluggable Authentication Module) is the most commonly used authentication mechanism that offers a common set of APIs for authentication.