Research And Implementation Of NAT Travesal Of Peer-To-Peer Networks

With the development of P2P (Peer-to-Peer) technologies, some software in file sharing and instance message, for instance, Maze, PPLive and Skype, has been used more and more online. P2P is a technology which enables connection and telecommunication between peers, while some NAT equipment disables unknown outer connections, which prevent the development of p2P. So how to discover other peers behind NAT and make a connection is one of the problems in P2P networks.First of all, the paper introduces the concept of P2P networks, and analysis three P2P modular covered in this paper. Also introduce NAT traversal theories over TCP, including NAT technology, types and implementation. And compares the advantages and disadvantages of approaches on the NAT traversal over TCP.Then the paper introduces the optimized mechanism based on NUTSS protocol, CNUTS, and provides the design framework, core coding implantation. The principle method is proposed two traversal modes:SYN/ACK mode and "simultaneously open"mode, which make a optimized mode selection based on the net conditions and NAT types to enhance the traversal success rates effectively.The paper emphasize on the design and implantation of traversal modular. At client and server point, user register, NAT type detection and selection of NAT traversal methods, updated messages modular are achieved in our system. And the test results identified the system can not only access to symmetric NAT, but also reach a high successful rates.Finally the paper gives summarizations and prospect to NAT traversal.