为了确保校园网的安全，查找出可能的攻击，本文设计并实现了一个简单的基于规则的网络入侵检测系统。整个系统可实现网络抓包、入侵检测和日志记载，能够检测出目前黑客最常用的一些攻击手段。本文还阐述了网络入侵检测系统的基本原理、功能与结构、检测引擎的构造、现有的检测技术、国内外最新的有关产品及发展方向；分析了校园网的入侵检测需求；说明了校园网入侵检测系统的内部机制和实现方法；最后还介绍了网络入侵检测系统的规则应用。-In order to ensure the security of campus network to find out possible attacks, the paper is designed and implemented a simple rule-based network intrusion detection system. The whole system can be realized network capture, intrusion detection and log records, be able to detect the hackers is currently the most commonly used means of a number of attacks. The article also elaborated on network intrusion detection system s basic principle, functions and structure, the structure detection engine, the current testing technology, both at home and abroad on the latest products and development　analysis of the campus network intrusion detection needs　explains Campus Network Intrusion Detection System s internal mechanisms and methods　finally introduced the Network Intrusion Detection System Application of the rules.