Nat Open Application Model And Design

Since ARPANET was applied to civil field in the 80's of the 20th century, it has achieved a great progress and the Internet has reached every corner of the world. With the fast expansion of the Internet, the resource of IP address will be soon run out.In the 90's of the 20th century, the shortage of IP address appeared. Thus, NAT technology has been introduced. Network Address Translation (NAT) is one of the effective solutions delaying IP address depletion. NAT has many advantages: implementation simplicity, flexibility of deployment, transparency of use, etc., so NAT is widely used in the Internet.In recent years, with new type application of network, such as application of IPSec protocol, there is an obstacle to make further advances of NAT. Preventing data transmitted from being edited in the whole process provides the security service of IPSec, but the address reuse of NAT based on IP address replacement. There is a lot of work done on the problem, all of these work is concerned only with partial solution, so can be only supplied to some special case. There is not a general solution at the present time.We have worked on the problem from other angles in this article. In theory, the interior structure of NAT device has great impact on NAT application. We redesigned a new application model of NAT; a NAT product conforming to the model is conducive to solve the NAT application problem.The other work we have done is studying algorithm, and we have designed a core algorithm for maintaining session map table.In the end, we give a solution to implement the model under windows 2000 OS.