Network Packet Interception And Manipulation Of Technology Research And Application

With the widly using of LAN, security problem inside the LAN is also getting austerity with every passing day. To protect LAN's safety, traditional firewall concentrates on keeping away outside network invasion to the inside network and attacking, to control the behavior of user inside of local area network is thought not enough. For an enterprise, guarding against the inside personnel illegal operation on network resource, ensuring local area network inside safety, and so on aspects, depending solely on tradition firewall is insufficient. Therefore, with regard to how to intercepting and filtering packets from the inner to external network is must be going to think.This dissertation mainly discusses local area network inside safety problem, involve in technology of intercepting network data packets, counterfeiting and controlling packets, as well as the TCP/IP protocols analyses and so on. The content in this thesis mainly includes: The TCP/IP protocols analyses and its application in the field of aether net safety, and emphasizes discussing LAN-monitor with ARP protocol analysing; Technology of intercepting network packets, mainly discusses packet-filtering technology based on Winsock SPI; Sniffer technology and its application in LAN monitoring and controlling, and discusses the application of packet analyses and counterfeiting. With investigation and discussion to all above content, the ultimate purpose is to apply technology of packet manipulating to LAN safety controlling.In the entire project, I am mainly in charge of designing and accomplishing the main module of the client, accomplishing subnet-monitor module, net-behavior monitor module and communicating module. This dissertation describes the design and operation of these key modules in detail, and emphasizes the design principle of subnet monitor module and also introduces how to monitor users' net behaviors on the client computer using technology of packet filtering, accomplish monitoring the following behaviors: Web visiting, FTP visiting, email transmiting-receiving and LAN document sharing and so on.