Research On And Realization Of Security Techniques For Voice And Video Over IP To Traverse NAT/Firewall

With the rapid development of information technology, VoIP has been widely applied all over the world. Moreover, transmission of voice, video together with data on IP networks has become a tendency, which has strategic significance for enterprises and organizations. However, most of them are facing a problem that NATs and firewalls prevent voice and video over IP from accessing.This paper studies the security techniques for voice and video over IP to traverse NATs/Firewalls, and proposes an effective and transparent scheme to pass through NATs/firewalls. Our solution to problems of traversing NAT/firewall features a novel multi-frontier technique that allows voice and video over IP to pass through NATs/firewalls regardless of their numbers existing in the network.The technical scheme based on the transparent traversing technique for voice and video over IP was discussed in details in this paper. Then, the Server Communication Protocol Module of the system was designed and implemented. Finally, on the basis of further study on the multithreading dispatching, message processing and communication mechanism, using TCP/IP Protocol as the interface of Server Protocol Module, some key modules concerning Client's request for connection, loading, analysing, transmiting of messages are implemented according to the operation priciples of the transparent traversing system.