Friday, August 28, 2009


Point To Point Protocol (PPP)

PPP was first proposed as a standard by the Internet Engineering Task Force (IETF) in 1989 and became a working standard in 1994. The IETF specification for PPP is RFC 1661. PPP is a protocol most widely used by Internet service providers (ISPs) to enable dial up connections to the Internet. PPP facilitates the transmission of data packets between point to point links. Originally designed to work with serial connections, PPP was adopted by ISPs to provide dial up Internet access. PPP can be encapsulated in a number of data link layer protocols, including Ethernet (PPPoE) and Asynchronous Transfer Mode (PPPoA).

PPP uses Link Control Protocol (LCP) to establish a session between a user's computer and an ISP. LCP is responsible for determining if the link is acceptable for data transmission. LCP packets are exchanged between multiple network points to determine link characteristics including device identity, packet size, and configuration errors.

PPP supports three types of user authentication protocols that provide varying levels of security. Password Authentication Protocol (PAP) is an access control protocol used to authenticate a user's password on the network access server. The network access server requests a password from the client machine and sends the retrieved password to an authentication server for verification. As an authentication protocol, PAP is considered the least secure because the password is not encrypted in transmission.

Challenge Handshake Authentication Protocol (CHAP) is similar to PAP with several unique characteristics. Instead of requesting a password, the network access server sends a challenge message to the client machine. The challenge message is a random value. The client machine encrypts the challenge message with a user's password and sends the combination back to the access server. The access server forwards the challenge/password combination to the authentication server.
The authentication server encrypts the challenge with the user's password stored in the authentication database. If the user's response is a match, the password is considered authentic. CHAP uses the model of a shared secret (the user password) to authenticate the user. The use of CHAP is considered a moderately secure method of authentication.

Extensible Authentication Protocol (EAP) is considered an authentication framework used by a number of secure authentication protocols. EAP is most commonly used for authentication on wireless networks.


rifone said...

charm posting about PPP, i had a problem abt my conection

mArNeLLe said...

Can you tell us about it,maybe we can help you.

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