路由器到路由器VPN试验网的组建和测试分析

介绍了VPN隧道技术PPTP，路由器到路由器VPN试验网的设计和搭建，以及用到的测试工具，并捕获PPTP数据帧。通过协议和数据帧分析，对实验网进行了性能测试。介绍了PPTP控制连接消息，分析和验证了PPTP控制连接过程、PPTP数据帧封装方式，加密方式及加密协议CHAP，具体分析了一个捕获的GRE报头，对报头的每一位进行了分析，进而验证了GRE报头格式，并分析了这种网络结构的安全性，最后给出了实验结论。

Foundation test and analysis of router-to-router VPN experiment Net

VPN tunnel technology PPTP, a Router-to-Router VPN experiment netand the testing tools are introduced, and PPTP data frames was cought at this net. By analyzing the characteristics of construction and the PPTP data frames, the performance of VPN experiment net was tested. PPTP controlling connection methods, the process of PPTP controlling connection, the encapsulation mode of PPTP data frames and the mode of encrypting and the encrypting protocol CHAP are presented. A captured GRE head and every byte were analyzed in detail to verify the GRE head construction. The security of this net construction was analyzed, and experiment conclusion is given.