What Is Password Authentication Protocol?

PAP is an acronym for Password Authentication Protocol. It is a method used to authenticate users who are trying to log on to a point-to-point protocol server.

Password authentication protocol

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CHAP uses unique and unpredictable challenge data to prevent playback attacks. The purpose of challenge numbers is to limit the time of data attacks. Regional servers (such as the Netscape Business Server) can control the frequency and time of sending challenge messages.

CHAP (challenge handshake authentication protocol) is an alternative protocol. It uses a three-way handshake to achieve periodic review and approval of network nodes. When the link is established, CHAP should have been completed and after the link is established, the review process can be repeated if necessary. This makes CHAP more effective than PAP. PAP only performs identity authentication once, which makes it easy for hackers to replay data, and PAP allows clients to initiate authentication applications, which also makes it vulnerable to hackers. Therefore, CHAP does not allow the client to initiate an authentication application without receiving a challenge message. After the PPP link is established, the server will send a challenge message to the remote end, and the remote end will send back a response value, and then the server verifies the return value according to its own value. If they match, the authentication will pass the confirmation, otherwise, the link will be terminated .