With the rapid expansion of computer networks during the past few decades, security has become a crucial issue in the computer systems. The purpose of network security is to protect the network from unauthorized access and disclosure. The recent advancements in the field of network security helps in the protection of computer systems and computer networks. One of the techniques used for making the network secure and detecting intrusions is Intrusion detection system. Intrusion detection system is a mechanism that detects unauthorized and malicious activity present in the computer systems.