Research And Implementation Of Files Audit System For Instant Messenger

The Instant messenger (IM), an essential tool to people's daily life, has brought users a lot of convenience. Howerver, it also imperils the nation and society's security, since the IMs make the spread of reaction and eroticism information easier.Therefore, research and designing of instant messenger files audit system is important to information security.Firstly, this thesis categorizes and introduces standard communication model IMPP for IM and two well-known IM protocol XMPP and SIMPLE in accordance with the model. Most of commonly used IMs use their own proprietary which are developed by the service providers their own. In view of this, the characteristics of the application layer protocol are unknown. Based on the building of the environment of the protocol analysis, we have a deep analysis and research on all kinds of instant messenger protocols and combined with relevant technology, this paper summarized the protocol characters of the Fetion, MSN, QQ and yahoo using the contrasting method.In the following, network packet capturing and processing technique on Linux platform is dicussed and the processes of protocol analysis based on Libpcap are presented. Base on this, we analyze the requirement and summarize the target of the system to proposal a solution for IM File Aduit system. With the basic functions, we partition the whole system to many modules and accomplish them step by step. The implementation refers to many important technologies, such as deep packet inspection, TCP stick package, data compression, TCP retransmission and so on. Then, some tests and analysis result of the system are given using test bed and and real network enviroment. It can be seen from the test results that FAudit can audit all kinds of files such as.txt,.doc,.pdf,.rmvb,.jpg and so on in various network environments no matter however bad it is.Finally, the thesis summarizes the current existing open issues, and provides some further directions.