The growth of internet technology spread a large amount of data communication. The communication of data compromised network threats and security issues. The network threats and security issues raised a problem of data integrity and loss of data. Initially, intrusion detection system work on process of satirical frequency of audit system logs. Latter on this system improved by various researchers and apply some other approach such as data mining technique, neural network and expert system. This trend of intrusion detection system used soft computing approach such as fuzzy logic, genetic algorithm and machine learning.