Design And Implementation Of Traversal Trough NAT Solution Based On STUNT Protocol

Because IPV4 only support limited IP Addresses,NAT Traversal is involved with today's Net communication.And there are many solutions for this problem now.For example:UPNP protocol proposed by Microsoft,"make hole"by UDP,Net proxy,ALG,STUN,TURN,ICE etc.NAT Traversal concerned technology is become a hot issue in Net communication.NAT Traversal can implement the peer to peer connection between two private Network users.It can reduce the bandwidth expense of Server,accelerate the Net transmission speed.Now the popular P2P technology post a higher requirement for NAT Traversal.Because of different NAT devices,the kind of NAT is different too,and generally all the NAT devices have firewall function,so there have not a technology can solve all Net Traversal problem.STUNT protocol is a extention of STUN protocol for TCP protocol,as is known to all,UDP is transaction oriented,and delivery and duplicate protection are not guaranteed.So it's implement is relatively simple.So many Net transmission protocol used UDP transmission protocol.But the weak point of UDP is obvious too,it doesn't have error control,connection control,flow control etc.STUN protocol only support UDP,but STUNT not only support UDP,but also support TCP,it's very practical.In order to implement this function,after brief inrtoduetion of Nat Traversal technology,this paper analyezs STUNT protocol and it's flow thoroughly,but traditional STUNT solution has some shortcomings and inadequacies,such as low success ratio,not in favour of symmetric NAT devices.Then this paper present a modified solution for NAT Traversal based on STUNT.This Solution resolve the shortcomings of traditional solution effectively.It depends on multiple interactions between Clients and Server,exchanging addresses in the transmission course,and reverse connection to implement direct connection between two communicating parties.At last this solution is tested and performance analysis.This solution is proven practical and effective by the experiment result.