• Password Authentication Protocol is like a virtual handshake.handshake image by Pavel Bernshtam from Fotolia.com
  
  A Password Authentication Protocol is a two-way handshake used to determine the success or failure of a password and user identification for a peer. Javvin warns that although a PAP may be used, it is not recommended since it is not a strong authentication method. The password is sent over a circuit in text format; this method does not block against playback, sniffing or attacks by trial and error.
  
  

Password Authentication Protocol

• Microsoft defines password authentication protocol as a simple method used to authenticate by sending the username and password to a remote-access server. The information is sent in a plain text form; plain text is not encrypted. Using this type of authentication method is generally discouraged since passwords are easily readable by the point-to point protocol packets; these packets are exchanged during the authentication process.
  
  

Point-to-Point Protocol

• Point-to-point protocol gives a standard method for transmitting multi-protocol datagrams through point-to-point links, according to Cisco. Three components comprise point-to-point protocols: encapsulating multi-protocol datagrams; methods for originating, constructing and analyzing data-link connections; and a group of network control protocols. The network control protocols are used to establish and configure various network-layer protocols.
  
  

Link Control Protocol

• The link control protocol is the most important part of the PPP protocols, according to TCP/IP Guide. The link control protocol manages all of the links and is overall responsible for the successful operation of other protocols. The three main stages used by lcp are: link configuration, link maintenance and link termination. In the link configuration stage, the parameters of a link are set up and negotiated. In stage two, opened links are managed. In stage three, an existing link that is not needed anymore is closed.
  
  

Challenge-Handshake Authentication Protocol

• Challenge-handshake authentication protocols are the most widely used security protocols, according to Microsoft. Instead of the actual password being sent to a remote server, a representation of the password is sent. A hash algorithm is then used by the remote client to establish a message-digest 5 based on a challenge and password submitted by the user. The remote client sends the information to the remote server; the same algorithm is used again to verify the information. Once the results are matched, the remote credentials are considered authentic. The hash algorithm provides only a one-way encryption, and determining the original data is mathematically impossible.