Network Information Security Audit Systerm Based On Content

As a sign of information age ,Internet offers millions of information and makes the people's daily life easy.But among millions of information ,some bad information is included,which seriously and harmfully affects the society.So It is necessary to audit the information that is transmited through Internet. Unfortunately,most of existing network aduit softwares are deveoloped mainly concerning about the respect of the network intrusion and aduiting the network access event and often are uneffective.This thesis designs and implements the network information security audit systerm based on content which can safely and effectively aduit the mass and real time network information.Firstly this thesis points out that developing the network information security audit systerm based on content is urgent ,Secondly it particularly shows the process of desinging and implemening the systerm.Thirdly it expatiates the three crucial technologies---BPF Network Packet Filters technology,Boyer-Moore string-matching algorithm, algorithm of Extracting Subject.Finally it indicates the report of thesysterm test and safely draws on a conclusion that the systerm is very in effect.