A Novel Approach of Detection and Mitigation of DDOS Attack

-We are in the era of internet and depend on it for every necessary requirement. It is the tendency of the some human to have destructive approach rather than having constructive approach. Among the abuse and misuse of internet, the distributed denial of service attack (DDOS) is the most hectic one. People have carried out various method of mitigation using the CAPTCHA (Completely Automated Public Turing Test to tell Computer and Human Apart) technique, but frequent use of CAPTCHA test for every access may turn the legitimate client away from the server. So our proposed mechanism tries to impose CAPTCHA test only after finding the suspected clients instead of applying to all the clients. The suspected clients have to go through a CAPTCHA test in order to get the access to the server. In our experiment we considered the slowloris attack which is one of the application layer DDOS attack. Keywords----Botnets, captcha, denial of service, filtering, intrusion, mitigation.