Abstract
Mobile ad hoc network (MANET) is a group of mobile wireless nodes that communicate with each other without the aid of the infrastructure such as base station. It has been used in many applications, for example, military application, personal electronic device, ad hoc meeting, etc. Because of the shortcoming of the routing protocol, MANET is vulnerable to some kinds of attacks. Black hole attack, gray hole attack, wormhole attack, traffic analysis attack, and rushing attack are common attacks in ad hoc network. In this thesis, we introduce a critical attack in MANET：the Route Request (RREQ) packets flooding attack. In RREQ packets flooding attack, malicious node floods RREQ packets rapidly and finally result in denial of service (DoS) in the network. Consequently, we develop a dynamic-threshold based scheme to detect this kind of attack. Our scheme uses two threshold values to defend the packets flooding attack. Besides, we adjust the thresholds according to the network status. Finally, the simulation results can verify the efficiency of our scheme.