Review of network intrusion detection

Computer network security is an international problem, Economic losses caused by breakage of computer network security system up to several billions of dollars on a global scale every year. After entering the new century, the loss will reach over 200 billion U.S. dollars. Inofrmation thieves in the past 5 years have been growing to 250%, 99% of large companies have been big in the invasion according to the statistics. World-famous commercial websites, such as Yahoo, Buy, EBay, Amazon, and CNN have been hacked, resulting in huge economic losses. Even RSA, specializes in network security web sites, has been attacked by hackers at some time in the past. Effective security policy or program development is the primary goal of network information security. Network security technology include authentication and authorization, data encryption, access control, security auditing. This paper focuses on intrusion detection technology which is the core technology in the security audit that is one of the network security protections of the important part.