Method for preventing IP attress leakage when using point to point protocol

This invention discloses a method for preventing leakage of IP address when using point to point protocol including: 1, starting ppp session to initialize the PPP session, 2, negotiating on PPP LCP and limiting times of successive LCP negotiations, 3, certificating PPP and assigning one time of IP address only to the AAA customer end, 4, carrying out PPP IPCP negotiation, during the negotiation, the beginning charging requirement is sent once only and the times of the successive PPP IPCP negotiations are limited, 5, stopping said PPP session and releasing said IP address.