Journal Homepage: www.ijcst.org

Abstract – Application Layer is the most important for development lifecycle, Application layer Distributed denial of service (DDoS) attack is a continuous threat to the World Wide Web. Derived from the lower layers, new application-layer-based DDoS attacks utilizing legitimate HTTP requests over to victim resources are more unavailable. This issue may be more critical when such attacks mimic or occur during the flash crowd event of a popular websites. Our technique presents on the detection of such new DDoS attacks, a novel scheme based on document popularity and also Access Matrix is defined to capture the spatial-temporal patterns of a normal flash crowd. A novel attack detector based on hidden semi-Markov model is proposed to describe the dynamics of Access Matrix and to detect the attacks. The entropy of document popularity fitting to the model is used to detect the potential DDoS attacks in application-layer. This paper analysis the attack detector with existing system drawback which presents proposed approach more efficient