The Design And Implementation Of Client Part In VPN System

With the development of Internet techniques, network has been widely used in social life and greatly speeded up the information exchanging. Nowadays, LAN (local area network) interdicts the connection to Internet by physical isolation, which can absolutely prevent intranet from internet attacks. However, it also limits the usage of Internet. Meanwhile, the internal attacks may also take place in the intranet. More attention has been paid to the security of the intranet. This paper focuses on the technique of VPN (Virtual Private Network), develop a VPN software with the name Milstar, and aims to improve the security of network data exchange.Based on analysis to modern VPN technique and actual usage of VPN in intranet, we divided the Milstar into four parts:server software, client software, remote management software, and certificate management software.As an important element of the VPN system, client part, which is implemented based on Windows platform, has the following main functions: client software which is transparent to users, identity authentication based on Smartcard, secure channel constructing, packet encrypting and decrypting, and the management of VPN. This paper puts forward the detailed design of graphics interface of client software.In the end, the threats in the typical intranet are analyzed, and a settlement to it with VPN was put forward.including the installation of the client, the way to construct a VPN tunnel connection, and the process of data encryption.