Deep Packet Detection Technology And Design

As network application technologies growing so fast, packet security not only relate to packet head scanning, but also content of application layer scanning which has become extremely important; In- addition, content security rules based on explicit string patterns in the face of growing network applications have become powerless. So that, deep packet inspection based on regular expression matching algorithm technology has become the main modern firewall technology. But due to DFA(Deterministic Finite Automata) representations, which are typically used to implement regular expressions , require huge amounts of memory and their computing performance depends largely on memory access speed , limiting their application. In this paper, we introduce a new pattern matching algorithm based on DFA representation of regular expressions, called SSDFA(Similar State DFA), which reduces memory cost of DFA representation of regular expressions, at the same time, remains high matching speed. Finally, a deep packet inspection system model based on SSDFA algorithm was given.