0前言所谓网络安全,实质上也就是网络上的信息安全。网络安全所涉及的领域是非常广泛的,但是在当前许多的公用通信网络中,都存在着各种各样的安全漏洞和威胁,随着网络技术的不断发展,各种各样的网络安全技术也相应的出现了,比如说身份验证、访问授权、加密解密技术、防火墙技术等等,虽然出现了许许多多的新的网络安全技术,但是在众多的网络安全技术中,防 0 Preface The so-called network security, in essence, is the information security on the network. The field of network security is very broad, but in many current public communication networks, there are all kinds of security vulnerabilities and threats. With the continuous development of network technologies, various network security technologies But also appeared correspondingly. For example, authentication, access authorization, encryption and decryption technology, firewall technology and so on. Although there are many new network security technologies, but in many network security technologies,