Spam Filtering Technology Based On Fingerprint Analysis

E-mail has become an indispensable tool to people living and working, but at the same time, spam has caused great harm, because of its overflow. Therefore, the anti-spam technology has always been hot topic in research domestic and oversea. This thesis makes a detailed analysis about the related characteristics of spam, and depth of its detection and control method.First of all, domestic and foreign current spam filtering technologies are analyzed in detail, including the process methods, effects and advantages and disadvantages. Based on the analysis of the study, found that, although these filtering technologies can achieve high identification accuracy, but most only start to identify spam when mails are completely received. Blacklist and reverse-domain which can be effective during mail transferring, could led spam escape easily. For this reason, the major work of the thesis is to search a more ideal filtering technology, in order to accurately identify spam when they are in transmission process.Secondly, as spam senders usually forge mail header, causing some field information of header ignored by mainstream filtering technologies. Through a lot of contrast and analysis, found that, spam, from the same source in a period of time, have same features in some fields in their headers. In order to describe these characteristics in a better way, this thesis presents and implements a fingerprint analysis technology, which based on mail header. According to 5 field in mail head, this technology generate its specific fingerprint, and process comparison on the basis of spam fingerprint database, carries accurate analysis and identification during the mail transmission. To improve the efficiency of the fingerprint extraction and comparison, this thesis adopts the MD5 encryption algorithm and binary tree to design and implement.Finally, as the current filtering techniques only process identification about spam, are lacks of inhibition measures to sender. Based on analysis about TCP reliable transmission, this thesis designs and implements three sender behavior control mechanism, including increase response delay, discard pocket and mixed mechanism. These mechanisms based on result from fingerprint analysis, block spam data transmission in different degree, control the senders'transmit efficiency, and achieve the purpose of reducing its throughput. This thesis through experiments proves that, this technology is usable and effective. At present, the fingerprint analysis and send behavior control technology, which this thesis discussed, have been integrated to enterprise-class garbage information comprehensive reporting system.