A CHAP Challenge Example
At the Corporate site is a NETServer with the Sysname of NETSERVE. A typical authentication might resemble the following:
1.A remote NETServer establishes a connection and negoti- ates for an authentication procedure.
2.NETSERVE becomes responsible for issuing a CHAP challenge. Inside that challenge is a User Name string containing the name NETSERVE and the random challenge string LASDFH;LASD.
3.When the remote NETServer receives the challenge, it checks its local User Table for the entry NETSERVE.
4.Finding the entry, the remote NETServer learns the shared secret password CHAP_PW and passes the string CHAP_PWLASDFH;LASD through MD5.
5.MD5 forms a response which the remote NETServer sends back to NETSERVE. Contained within the response is a User Name containing the Sysname of the remote NETServer.
6.NETSERVE then looks in the User Table for the name of the remote NETServer, and uses the password and the challenge string to validate the CHAP response received from the remote NETServer.
7.If the password comparison is successful, NETSERVE will then send a CHAP successful message back to the remote NETServer and the connection is complete. If the MD5 comparison fails, a CHAP failure message is sent to the remote NETServer and the process repeats.
