Abstract: Peer-to-Peer (P2P) computing environment is suffering increasingly serious propagation and attack of malicious codes. This paper adopted the Multi-Mobile Agent to construct a novel proactive immune mechanism suitable for P2P network systems. The biological immune principle was referred in this paper,and Multi Agent technology was utilined to realize Agents with different functions, which build cooperation relationship among the Central Immune Peer and ordinary Peers to defend malicious codes jointly. Mobile Agent can roam throughout P2P network to detect malicious codes actively or to carry and set long distance immune modules like vaccines. It is convenient to achieve rapid responding, analyzing and dealing malicious codes. In order to distribute immune modules efficiently, the paper also proposed a new Exponential Tree Plus (E7+)and vaccine distribution algorithm based on E7+.This paper first analyzed the propagation of malicious code in P2P networks, and then introduced the architecture and components of P2P networks proactive immune mechanism based on Multi Mobile Agent, as well as the ETA-based vaccine distribution algorithm, which performance was described at the end of this paper.

Key words: Peer-to-peer computing, Malicious code, Agent, Proactive immune, Exponential tree plus