Research And Implementation Of Active Security Mail Gateway

With the rapid development and popularization of E-mail technology, security mail gateway becomes one of the most important email security guarantees for the special network of governments and military enterprises. Security services provided by traditional email gateway include virus email detection and spam email detection. At present, products of gateway at home and aboard are based on international standard protocol and do not have the function such as the prevention of information leakage, which is essential for the safety of email service.In order to solve the problems of traditional mail gateway, this paper makes a research of security problems of email systems as below. Firstly, it designs the structure of the Active Security Mail Gateway. Secondly, it designs the Active Mail Transfer Protocol(AMTP). Thirdly, it designs and realizes the receiving module, the authentication module and the transmit module based on AMTP. Fourthly, this paper researches on the Markov-Models and improves the algorithm of the malicious mail detection based on Markov-Models. Fifthly, it researches the analysis of the usual format of email attachment and realizes the prevention of mail information leakage. Finally, the paper researches the technique of transparent bridge, and finishes the system environment configure.According to the characteristics of the special network, the AMTP protocol guarantees the mail transmission's reliability, security and undeniability. The mechanism which is designed for the prevention of mail information leakage realizes the decoding of the usual format of email attachment such as doc, pdf, xls and txt, and solves the automatic scanning problem of email content and attachment. The research results have been used in the network of a certain department as project background for several times, indicating that this system has achieved all the design requirements, and has features of malicious mail and secret mail active blocking.