“…VPN technology is to build a virtual line at both ends of traditional communication, however, compared with the line technology, VPN technology has the advantages of [2]: (1) the best open protocol that can be easily for the expansion of the system; (3) a variety of bandwidth available, and the upgrade is very convenient [3]; (4) and low investment cost, one-time investment, long-term view of saving the cost of enterprise. Relevant data show that in the LAN-to-LAN connection, VPN technology is used for cost savings of about 30%-50%; and remote access, using VPN can save about 60%-80% than the cost of direct dial in to the enterprise internal network, the prospect of it, therefore has extensive application of VPN technology in industry [4].…”