Network security is a weak link in wired and wireless network systems. Malicious attacks have caused tremendous loss by impairing the functionalities of the computer networks. Denial of Service (DoS) and Distributed DoS (DDoS) attacks are two of the most harmful threats to the network functionality. Mobile Ad Hoc Networks (MANET) are even more vulnerable to such attacks.. Denial of Service (DoS) is the degradation or prevention of legitimate use of network resources.. In this paper we analyse the flooding attacks in mobile ad hoc networks that support anonymous communication. Then we propose a novel technique to deal with the flooding attacks. Our approach can efficiently identify and isolate the malicious node that floods the network. In addition, our technique provides a mechanism to identify detection of malicious node and its numbers .In our simulation, we have taken the following parameters and analyzed the results using Energy consumption, routing overhead, packet delivery ratio and detection rate.