Mobile Ad-hoc NETwork (MANET) is inherently vulnerable to many attacks especially routing attacks. Routing protocols proposed for MANET assumes that all nodes within network are cooperative. This assumption creates a room for attacker to satisfy their malicious intent. Main vulnerability of many routing protocols used for MANET lies in the route discovery phase of these protocols. Intrusion Detection System (IDS) keeps watching for suspicious activities within a network and then initiates appropriate action against them. There are many approaches for intrusion detection in wired network but applying them directly into wireless environment is not feasible.