The tradition safety technique such as authenticate, accredit, encrypt, fire-wall and the control of accessing can not protect the information of network well. The safety of network faces great challenge and imperil.

• 传统的安全保护技术如认证、授权、访问控制、防火墙和加密等外围防卫机制已力不从心,计算机网络信息安全正面临着极大的威胁和挑战。