This paper first described the architecture of the IPSec specification, including AH, ESP, IKE, DOI, policy etc, introduced the application of IPSec, focused on the tunnelling technique, and show a reality framework of IPSec tunnel mode.

The paper is dealing with the IPSec Protocols and analysing the structure and key technology of security association , authentication header , encapsulating security payload and Internet key exchange.

THE ANALYSIS OF IPSEC IKE PROTOCOL;

Based on Internet key exchange protocol IKE, describes the identity authentication in key exchange protocol, and proposes some amelioration to improve efficiency of the protocol.

Password authenticated key exchange protocol under distinct authentication servers;

A new key/multi-key exchange protocol;

An implementation scheme of key exchange protcol IKEv2;

Analysis and Amendment of IKE Protocol;

The Internet Key Exchange (IKE) protocol is a hybrid protocol made of Internet Security Association and Key Management protocol, OAKLEY protocol and SKEME protocol.

This paper presents some rationale and key technology relevant to the implementation of VPN based on IPSec,briefly describes the main mode exchange of IKE with pre-shared key authentication method and,according to the flaw of IKE,suggests a solution to the improvement of the protocol,which can protect against man-in-the-middle attack and repeat attack.