Researches On The TCP-based NAT Traversal Technology Of P2P

With the development of the Internet and the increasing growth of computing and storage capacity of various terminals, P2P technology has been widely applied. Because of the limitation of the IPV4, many NAT equipments were deployed. These NATs have been the bottle-neck of the data transport in P2P networks. So how to discover each other and how to establish a direct link between nodes behind NAT becomes a big problem for P2P application. The thesis gave a new safely data traversal mechanism base on TCP protocol named STNTrav (The Safe TCP-based NAT Traversal Technology, STNTrav) , it can help to solve these kind of problems.The basic principle and classification of NAT are discussed at first. Then by analyzing existing traversal methods, a new TCP-based NAT traversal model is proposed, and some details of implementation of this model are presented.This thesis introduces the history and recent researches of P2P technology and its application on different areas. And then this thesis analyzes the difference and similarity of the traversal mechanism P2P environment. The basic principle and classification of NAT are discussed at first. Then by analyzing existing traversal methods, a new TCP-based NAT traversal model is proposed, and some details of implementation of this model are presented..The new feature of the STNTrav is the self-selection algorithm. This algorithm can detect the kind of the NAT and selection the suitable methods to traverse the NAT. the self-algorithm are very flexible. And the safe-control mechanism is also introduced into the STNTrav. It employ the username-password authentication and SYN-Cookie technology to avoid the Dos attack.In the end, the thesis simulates STNTrav traversal mechanism. The simulation testifies that the mechanism can help data transport by self-selection traversal algorithm and the effectiveness of mechanism can satisfy the need.