Password Authentication Protocol

networking (PAP) An authentication scheme used by PPP

servers to validate the identity of the originator of the

connection.

PAP applies a two-way handshaking procedure. After the link

is established the originator sends an id-password pair to the

server. If authentication succeeds the server sends back an

acknowledgement; otherwise it either terminates the connection

or gives the originator another chance.

PAP is not a strong authentication method. Passwords are sent

over the circuit "in the clear" and there is no protection

against playback or repeated "trial and error" attacks. The

originator is in total control of the frequency and timing of

the attempts. Therefore, any server that can use a stronger

authentication method, such as CHAP, will offer to negotiate

that method prior to PAP. The use of PAP is appropriate,

however, if a plaintext password must be available to

simulate a login at a remote host.

PAP is defined in RFC 1334.

(1996-03-23)