Abstract
Mobile ad-hoc network could be a collection of node that is self-configuring, decentralized, framework less mobile network .As a result of open nature of the network simply liable to numerous attacks. The main security threat on MANET could be a DDoS attack. Distributed Denial of Service (DDoS) attacks are a virulent, relatively new type of attack on the availability of Internet services and resources. DDoS attackers infiltrate large numbers of computers by exploiting software vulnerabilities, to set up DDoS attack networks. As specific countermeasures are developed, attackers enhance existing DDoS attack tools, developing new and derivative DDoS techniques and attack tools. It would be desirable to develop comprehensive DDoS solutions that defend against known and future DDoS attack variants.