I. Introduction
With the increase of network penetration rate and the rapid development of network application, cyber security has become one of the biggest challenges that network developers and managers have to face [1]. Activities that attempt to bypass security mechanisms are usually considered as intrusions. A large amount of network intrusion incidents are reported each year. Network Intrusion Detection System is regarded as a very important foundation and prerequisite for identifying malicious activities and handling cyber attacks in network traffic. NIDS monitors the network traffic and scans the system for suspicious activities and alerts the alarm.