摘要： 通过对Linux内核和Netfilter框架的分析和研究，提出了一种集多种安全功能于一身的复合网关。该网关将防火墙、入侵检测和内容过滤3种安全功能用内核模块的形式实现，利用Netfilter框架的扩展功能，将各个安全模块加载进内核，从而在内核中实现对网络不同层次的安全功能的整合。

关键词: Netfilter, 包过滤, 入侵检测, 内容过滤

Abstract: By analyzing and studying the Linux kernel and Netfilter framework, This paper presents a hybrid gateway, which integrate multiple secure functions. The gateway implements the functions of firewall, intrusion detection system and content filtering as kernel modules and loads up these modules into kernel by utilizing the expansibility of Netfilter framework. Then the gateway implements the integration of different secure function at different layer of network.

Key words: Netfilter, Packet filtering, Intrusion detection, Content filtering