Intrusion detection system(IDS) is must to detect malicious activity in a network. In this paper we are concentrating on accuracy and efficiency in network to detect whether the packet as intruder element. We are using layered based approach, with this approach more time is saved. There are four layers in this system probe, DoS, R2L, and U2R, a packet first checked for probe attack first if there is attack then the packet is dropped. If there is no attack it will pass to DoS layer. Similar approach is taken for other three layers. There are 41 features to detect whether the packet affected or not. It is not necessary to check all 41 features in all the layers for this CRF mechanism is used with this approach we can detect the attack efficiently and accurately.
intrusion detection, layered based, CRF, kdd99
