An Ad Hoc network is a collection of wireless, mobile nodes that dynamically form a network without the use of centralized, fixed network infrastructure. Inherent characteristics of an Ad Hoc network such as dynamic topology and limited physical security poses severe security challenges to the network. Hence, these networks demand much stronger security mechanisms than the traditional, wired and static networks. Well established contemporary routing protocols seem to adapt to the dynamic conditions as well. However, they provide either no security mechanisms at all, or have only partial solutions for protecting the dynamic routing framework.
It is hard to achieve security and robustness in the routing protocols at the same time in such networks. Several issues have to be understood and addressed before devising a security mechanism. Moreover, challenges involved in addressing attacks differ from one protocol to the other. This thesis targets at securing reactive routing protocol AODV. The routing protocol is vulnerable to two kinds of attack: External and Internal attack. We have discussed some existing external attacks and possible malicious behavior from compromised nodes. To mitigate the attacks, we propose a dual level security model. On the first level, we have External Attack Detection Model(EADM), that secures the network with authentication and confidentiality that rely on mutual trust between nodes. And on the second level, Intrusion Detection Model (IDM) identifies the misbehaving nodes using the knowledge base and Response Model (RM) isolates these nodes from the network.