I INTRODUCTION
The rising popularity of the computer to the human
production and living has brought the revolutionary
change, at the same time, its own there is also a major
security hidden trouble, network security has become a
computer network using one of the most pressing
problems. The core of the computer network security is to
protect the safety of network information resources, the
protection of network storage and flow of information
resources does not malicious damage or leakage. Some
important information resources more need to be
protected, in order to prevent the use of various network
technology theft or damage. For example, some is related
to national security or science and technology of
important information resources, once the leak could
disrupt social order, and lead to serious economic loss.