Research And Implementation Of Network Content Audit System

With the development of network, more and more corporations have built their ownnetwork that connected to the Internet. The network, along with its popularity and greatconvenience, has also brought new problems, for example, the illegally trade ofbusiness or technical information, dissemination of porn information, and moreseriously, using the Internet for illegal activities. As a solution, a well designed auditingsystem can be great help on locating problems and solve them in time.This thesis provides an auditing system based on the bypass data collection, themain purpose is to identify illegal network communications and record. The system cancapture email and the attachment file and to completely restore the contents, in order toform evidences.This thesis first analyzes various possible techniques of the auditing system in useand describes its function position and core processes based on the bypass accesstechnique.On this basis, the overall structure of the system is analyzed. Besides, thedesign theory and infrastructure of each system module are described in detail.Moreover,string matching is one of the key techniques in the network contentaudit,where matching speed directly affects the performance of audit system. Based onthe Sunday pattern matching algorithm,a new algorithm named Sunday2is proposed. Itfinds the2words after the text when the last matching fail, and then compares the2words and the pattern string to move as far as possible, and in the matching process, thefirst matching pattern string characters of low probability of occurrence in order toreduce the number of matches.At last, this thesis tested the system.The result showes that this system obtained the performance as expected,and through the analyses,the advantages and disadvantages ofthe system are summarized as well. Furthermore, it points out the direction of thefollowing research of the network content audit system.