PAP, Password Authentication Protocol

Often referred to as Password Authentication Procedure, PAP is used for PPP (Point-to-Point Protocol) links. It offers a method of peer to peer communication using what is known as a 2-way handshake. This process occurs only upon the initial establishment of a link. Once the task of link establishment is complete, a username and password is transmitted from the sender to the authenticator until there is either validation or the session is terminated. PAP is not the most secure method of authentication. The process transmits passwords in plaintext, giving no protection against packet sniffing and other attacks. Any additions intended to make this procedure stronger must be implemented prior to PAP. In PAP, the authentication procedure is best used when a password in plaintext is required to be available in order to simulate a login on a remote host. This method provides a level of security nearly identical to the original user login procedure on the remote host.