Survey on intrusion detection methods

Intrusions in an information system are the activities that violate the security policy of the system, and intrusion detection is the process used to identify intrusions. Intrusion detection has been studied for approximately 20 years. It is based on the beliefs that an intruder´s behavior will be noticeably different from that of a legitimate user and that many unauthorized actions will be detectable. Intrusion detection systems (IDSs) are usually deployed along with other preventive security mechanisms, such as access control and authentication, as a second line of defense that protects information systems. There are several reasons that make intrusion detection a necessary part of the entire defense system. This paper describes various Intrusion Detection methods like pattern matching, state full pattern matching, protocol decode-based analysis etc and how fuzzy clustering can apply in IDS.