Abstract: “As the importance of computers are increasingly integrated into the systems the ability to detect intruders in computer systems also increases as we rely on for the correct functioning of society.Intrusion detection is a mechanism used to detect various attacks on a wired or wireless network. The process of monitoring the events occurring in a computer system or network and analyzing them for sign of intrusions is known as Intrusion Detection System (IDS). There are two basic approaches: anomaly detection and misuse detection. Both have naturally scaled to use in distributed systems and networks. This paper reviews the history of research in intrusion detection as performed in software in the context of operating systems for a single computer, a distributed system, or a network of computers.”

Keywords: Anomaly detection, Distributed System, Intrusion Detection , Network.