随着计算机网络的发展,其开放性、共享性、互连程度扩大,网络的重要性和对社会的影响也越来越大。而网络安全问题显得越来越重要了。一般来说,计算机系统本身的脆弱性和通信设施脆弱性共同构成了计算机网络的潜在威胁。 With the development of computer networks, its openness, sharing, and interconnection have expanded, and the importance of the Internet and its impact on the society have become greater and greater. The problem of network security is more and more important. In general, the fragility of the computer system itself and the vulnerability of the communications infrastructure together constitute a potential threat to the computer network.