Abstract: Wireless communication represents a major industrial stake in the coming years. The mobility and scalability brought by wireless network made it possible in many applications. It targets applications in harsh environments such as war zones, emergency recovery, power plants and warships etc. MANETs is one among the wireless technology which is widely used. MANETs does not need any pre-configurations or permanent network architecture or infrastructure compared to wired technology. The wireless links between the nodes together with the dynamic-network nature of ad hoc network, increases the challenges of design and implement intrusion detection during the attacks. The intrusion detection system is achieved through a mechanism calledSecure Acknowledgment(S-ACK) which is more elegant than watchdog.

Keywords: Mobile Ad hoc NETWORK (MANET), Watchdog, Secure Acknowledgment(S-ACK),Digital Signature.