0引言随着信息科技的快速发展,网络已成为日常生活的一部份,政府机关、企业机构利用网络来提供服务的比例愈来愈高。然而,我们在享受网络所带来的便利性之余,随之而来的网络安全问题却不容忽视。常见的网络威胁主要有重要机敏资料遭窃取或篡改、个人数据外流、网络服务的中断、严重的甚至造成系统瘫痪。为了应付上述威胁,人们使用各种技术来保护网络安全,诸如:防火墙(Firewall)、入侵检测系统(Intrusion Detection System,IDS)、 0 Introduction With the rapid development of information technology, the Internet has become a part of daily life. Government agencies and enterprises use the Internet to provide more and more services. However, while enjoying the convenience brought by the network, the ensuing problems of cybersecurity can not be ignored. Common cyber threats mainly include theft or tampering of important and sensitive information, the outflow of personal data, the interruption of network services, and even serious paralysis of the system. To cope with these threats, people use various technologies to protect their networks, such as firewalls, intrusion detection systems (IDSs), firewalls,