Deep Packet Inspection Base On KMP Algorithm Is Used In The Next Generation Of Firewall

The firewall technology is the footstone of the network security. Facing more and more attacks to application layer data and DoS(Deny of Service).The firewall come across two problems mainly. First one is how to make firewall software more portable and independent from platform while protecting the application layer data. The other one is how to strengthen their defense ability without compromise their performance.The key technologies of the traditional firewall are packet filter, stateful inspection and application proxy. Packet filter and stateful inspection do well in the protection of transmission layer, but it is powerless in application layer protection and content filter. Application proxy is designed to protect application layer, but it can not be deployed easily and deal with high-speed data stream.The author explored the elements of deep packet inspection and its typical representation—stream filter. With intense analysis on the essence of the TCP handshaking procedure and the main points of stream filter. Stream filter technology recombines datagrams which belong to the same session and filter the data after recombination with KMP algorithm.