基于扩展ICE框架的NAT穿越技术研究

发布时间：2018-05-01 06:36

本文选题：实际网络 + 对称型NAT　；参考：《哈尔滨工业大学》2014年硕士论文

【摘要】：随着多媒体通信技术和互联网技术的不断发展,点对点之间的通信要求变得越来越高。如何使两个客户端在不同的网络间实现稳定,快速连接传输的P2P(peer-to-peer)通信成为热门研究课题。特别在复杂网络环境下,这种研究和相关技术实现更显得非常重要。NAT(Network Address Translator,网络地址转换)的存在解决了IP地址短缺的问题。SIP协议(Session Initiation Protocol,会话发起协议)的提出提供了两客户端之间会话连接建立的技术标准,但是,NAT的存在使得私有网络的SIP信息数据包无法在公有网络上路由。为了实现在实际网络结构中可靠的网络穿越连接,保证SIP信息数据包在不同局域网间传输,一方面,本文使用TCP连接代替UDP连接进行NAT穿越,模拟TCP三次握手完成NAT连接,避免在网络不稳定或者带宽受限等情况下,因为UDP丢包不可靠连接的性质而引起NAT穿越不成功。另一方面,鉴于实际网络环境中比较常见的对称型NAT网络设备很难穿越成功,本文在原有ICE(Interactive Connectivity Establishment,交互连通建立)框架理论基础上,重点提出了一种改进ICE候选地址机制的网络穿越方案,给出了对称NAT类型的端口映射方式的分类以及相对应的端口预测功能,从而解决了对称NAT类型网关的网络穿越问题。尽量避免中继传输所引起的网络负载压力增大问题,有利于提高连接服务质量。基于上面提出的两方面,本论文的程序基于PJSIP协议库实现,在PJSIP协议栈中添加了端口预测功能化模块,并在实际网络环境中进行了测试,数据结果显示所添加的模块符合预期效果,端口命中率符合理论值。
[Abstract]:With the development of multimedia communication technology and Internet technology, the requirement of point-to-point communication becomes higher and higher. How to make the two clients stable between different networks and how to quickly connect P2Ppeer-to-peer communication has become a hot research topic. Especially in the complex network environment, This kind of research and related technical implementation become more important. The existence of NATN Network Address translator (network address translation) solves the problem of IP address shortage. Sip protocol session Initiation protocol (session initiation protocol) provides a session connection between two clients. The established technical standards, However, due to the existence of Nat, private SIP packets cannot be routed over public networks. In order to realize reliable network traversing connection in actual network structure and ensure the transmission of SIP information packet between different LAN, on the one hand, this paper uses TCP connection instead of UDP connection to traverse NAT, and simulates TCP three times handshake to complete NAT connection. In the case of network instability or bandwidth constraints, NAT traversal is not successful because of the unreliable connection properties of UDP packet loss. On the other hand, in view of the fact that symmetric NAT network devices are difficult to traverse successfully in the real network environment, this paper bases on the original ICE(Interactive Connectivity establishment (interactive connectivity) framework theory. In this paper, a network traversal scheme with improved ICE candidate address mechanism is proposed, and the classification of symmetric NAT type port mapping mode and the corresponding port prediction function are given, thus solving the network traversal problem of symmetric NAT type gateway. The problem of network load pressure caused by relay transmission is avoided and the quality of service is improved. Based on the above two aspects, the program of this paper is implemented on the basis of PJSIP protocol library, and the port prediction function module is added to the PJSIP protocol stack, and tested in the actual network environment. The data results show that the added module conforms to the expected effect and the port hit rate accords with the theoretical value.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TP393.04

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