With the growing use of the Internet infrastructure for commercial applications, the demand for quality of service has rapidly increased. Hence, wireless Sensor Networks (WSN) are emerging as both an important new tier in the IT ecosystem and a rich domain of active research involving hardware and system design, networking, distributed algorithms, programming models, data management, security and social factors. Ad hoc networks are simple peer-to-peer networks, self-organized and with no fixed infrastructure hence the Adhoc networks are more easily attacked than a wired network. They are used in the military oriented tactical operations, for emergency law enforcement, and in rescue missions. Confidentiality, integrity, availability, non-repudiation and the authentication are the basic requirements of the information security. Reachability information is shared between the routers by the routing protocols. As traffic is received at a router, it is forwarded based on the reachability information stored in the router’s forwarding table, and the other information stored in the packet’s header.