password authentication protocol (PPP) (PAP)

The Password Authentication Protocol(PAP) is a simple authentication protocol used to authenticate a dial-up person by user ID and password.

The PAP protocol is an integral part of the Point to Point Protocol( PPP) and is described in RFC 1994. The procedure works according to the two-way handshake, in which the client, after establishing the connection, sends its user ID and password unencrypted to the server, which performs the verification. If they match, the server responds with a confirmation and allows access to the network. If the input is incorrect, the connection is terminated.

Due to the unencrypted transmission of the password, the PAP protocol is considered relatively insecure.