Abstract: This paper presents an approach to intrusion detection based on rough set and genetic reduction algorithm.The proposed method uses a hybrid method that employs the genetic algorithm and improved greedy algorithm to find a possibly short reduction.It will obtain some intrusion detection rules after value reduction.Experiments on KDDCUP99 data set show that the proposed method can obtain outstanding results on intrusion detection.Moreover，the improved hybrid genetic algorithm has better performance in terms of running time.

Key words: rough set, intrusion detection, greedy algorithm, genetic algorithm

摘要： 采用改进的贪心算法和遗传算法结合的混合遗传算法进行属性约简，并利用值约简后生成的入侵检测规则，提出一种基于粗糙集理论和遗传约简算法的入侵检测方法。基于KDDCUP99数据集的实验表明该方法取得了良好的入侵检测效果，并且改进的混合遗传算法生成约简的速度更快。

关键词: 粗糙集, 入侵检测, 贪心算法, 遗传算法