Ipsec-based Virtual Private Network Technology Research

Virtual Private Network (VPN) technology is one efficient way to solve network security problem. It can be used to construct private network for enterprises by using the existing network resourses. The advantages of VPN include saving the network resourses and providing the security which is better than phisical private network. Tunneling technique is the key technique to implement VPN. In all kinds of existing Tunneling techniques, IPSec protocol, which is brought forward by IETF, can provide the preferable security.It can ensure the security of the important data of enterprises by using the tunnel mode of IPSec to construct VPN. Based on the current status of Greatwall Network, using VPN technology can provide a better solution for all kinds of user units to construct their private network. This thesis introduces the conception and key technology of VPN, and has makes a comparative research on the existing tunneling protocols. The principle of IPSec specification is accounted for in detail. The open software FreeS/WAN which implements the IPSec protocol is analyzed, and the author's opinion is presented. FreeS/WAN is installed and tested in the simulation environment of Greatwall Network,. In the end, this paper gives a VPN solution to air force as a example, and discusses some key technical items such as improving FreeS/WAN and promoting the network's Qos.