Abstract: With the popularity of the P2P technology， the security problem on P2P network has attracted more and more attention. To address the issue， a model called P2P-VPN virtual network framework is proposed， which sets up a virtual network group according to the specific application. The framework is not only to achieve the secure P2P transmission， but also to apply P2P technology to the local area network applications. The completeness of security mechanism of P2P-VPN is proved by Petri Nets and some other formal methods. The simulation results from the prototype system show that although the framework introduces a series of security processing procedure， it will not cause significant decline in data transfer rate.

Key words: peer to peer （P2P）, virtual private network （VPN）, P2P-VPN, Petri Net

摘要： 随着P2P技术应用范围的进一步扩大，P2P（peer to peer）网络的不安全因素逐渐为人们所重视。针对这个问题，结合VPN（virtual private network）技术的优势，提出了一种P2P-VPN虚拟网络架构模型，面向具体应用建立虚拟网络组，不仅实现了组内P2P安全传输，还把P2P技术扩展到局域网应用领域。利用Petri网等形式化方法证明了安全机制的完备性，提出了模型的基本性质。原型系统的仿真结果表明，P2P-VPN架构虽然在P2P网络上引进了一系列安全处理过程，但不会造成数据传输率的大幅下降。

关键词: P2P技术, VPN技术, P2P-VPN, Petri网