Abstract: This paper reviews intrusion detection，data mining techniques and analyses the snort NIDS in depth.Then a snort-based NIDS model enhanced with data mining techniques is developed，with efforts given to its key modules in abnormal detection engine，the cluster analysis module based on k-means algorithm.The k-means algorithm modified is adopted better in NIDS.

摘要： 回顾了当前入侵检测技术和数据挖掘技术，对Snort网络入侵检测系统进行了深入的剖析；然后在Snort的基础上构建了基于数据挖掘的网络入侵检测系统模型；重点设计和实现了其中基于k-means算法的异常检测引擎和聚类分析模块，并对k-means算法进行了改进，使其更适用于网络入侵检测系统。