L2tp-based Virtual Private Network Technology And Research

Virtual Private Network (VPN) technology is a kind of developing and popular network technology in recent years. WAN is used by government departments with many subsections and large enterprises with many branches to connect these. subnet. But the special line technology was adopted in past time. The advantage of the special line is safety and convenient, but its costs too expensive to be born by users. In 1990s, with the high progress of Internet, we hope to set up network of large enterprises with cheap Internet source. But the safety of Internet is very low, which can' t meet the requirement of enterprise' s network. So these enterprises don' t set up important network communication on the Internet for safety problems.VPN technology comes into being in the situation, which we pay more attention to. It transmitting private data via the public network. Internet may be adopted as main network to set up safety and reliable large network in VPN technology. Authentication, encrypt and tunneling technology are integrated in VPN technology. So VPN will be instead of the special line to perform network interconnection safely. And enterprises and government departments can transmit the important information via Internet. So the cost is low, which is used to set up and repair the special information network. At the same time, the ability of flexibility connection of the network is in progress. So VPN technology is a kind of valuable technology.It is adopted by government departments and enterprises in west at present. And it begins to be used in our country, but it has a fast progress. All kinds of key technology are analysized in this article. On the basis VPN system is researched and developed. And two important agreements of VPN (L2TP and IPSec) are introduced. On Linux , according to RFC2661,ones have realized the key part in L2TP agreement: LNS server. Which makes the ordinary windows customer who is in public net hold the LNS server that installs through VPN group number on direct company on Linux, visit LAN. Ones have realized the VPN of safe reliable high speed with very cheap price. All the system mainly have three functions, tunneling used of L2TP, encryption used of IPSec and authentication used of PAP, CHAP, RADIUS. VPN was test in real environment after it is developed completely. The test result shows that VPN system may meet transmit data safety via Internet. So VPN system is of great use.