Anomaly based intrusion detection attracting many researchers and networking companies due to
vulnerability in the networks. In this paper we presented a detailed review of some important anomaly based
intrusion detection techniques and their properties along with some useful related work. Despite the fact of
such enormous work on intrusion detection, still there is enormous work to be done in anomaly intrusion
detection. The false alarm rate of anomaly based detection is high as compared to signature based. The choice
of technique totally depends on the various factors such as type of anomalies, processing data type and
behavior, working environment of the organization, computational cost and the security level required.