| Information security is a very important issue that today’s Network community is facing. The future development of electronic and information technology then will be subject to the impact of network security. Today the most widely used network security technology is firewall. It can filter information, arid play a very important role in the defense of the harmful information. The trend of the future firewall is its powerful filtering capabilities. It can effectively block harmful information. However, with the development of network and the upgrade of hacker technology, the original simple firewall can’t meet the needs of network security. It is necessary to turn to consider the defense of the whole security system.This study is mainly based on the NDIS layer firewall. Through the parse of the network protocol, the firewall can detect which is behavior harmful to the network, and then filter out these harmful behaviors according to network firewall filtering rules. The most convenient and most direct way of network security is the driver layer packet filtering technology. The base layer packet filtering technology realized in the NDIS intermediate layer is the key technology of the Windows Firewall. It is able to intercept all network packets, and is the most efficient running program. The interpreting of network protocols can reconstruction and analysis the intercepted package, and retrieve the content of the website and the messages. The retrieved content is classified and compared with the library of network behavior. Then it is easily to determine whether the network behavior is illegal or not. Meanwhile, the network behavior-based detection can easily and quickly determine whether the network behavior and the objects of this behavior are normal. It can distinguish the abnormal flow which only occupies a small proportion from the normal traffic, so that the detection system only focuses on the network traffic which really needs further analysis to dramatically improve the efficiency of the firewall system. |
