关键词: 协议识别, 正则表达式, 最优DFA状态数, One-Pass扫描算法

Abstract: Traditional methods of application-layer protocol identification such as using default server port are no longer applicable to a large number of random ports application.A dynamic application-layer protocol identification based on regular expression is designed.Through analyzing the impact of number of DFA states to the algorithm performance，a DFA state number optimization algorithm is proposed.This algorithm has the little time complexity and space complexity under the limited system resource.And then packet matching patterns are tested with One-Pass scanning algorithm.Experimental results show that this program has a lower rate of resource consumption，higher efficiency of the identification and recognition accuracy.

Key words: protocol identification, regular expression, DFA state number optimization, One-Pass scanning algorithm