Biblio

Distributed Denial of Service (DDoS) attacks aim to make a server unresponsive by flooding the target server with a large volume of packets (Volume based DDoS attacks), by keeping connections open for a long time and exhausting the resources (Low and Slow DDoS attacks) or by targeting protocols (Protocol based attacks). Volume based DDoS attacks that flood the target server with a large number of packets are easier to detect because of the abnormality in packet flow. Low and Slow DDoS attacks, however, make the server unavailable by keeping connections open for a long time, but send traffic similar to genuine traffic, making detection of such attacks difficult. This paper proposes a solution to detect and mitigate one such Low and slow DDoS attack, Slowloris in an SDN (Software Defined Networking) environment. The proposed solution involves communication between the detection and mitigation module and the controller of the Software Defined Network to get data to detect and mitigate low and slow DDoS attack.

DDoS attacks are pre-dominant in traditional networks, they are used to bring down the services of important servers in the network, thereby affecting its performance. One such kind of attack is HTTP GET Flood DDoS attack in which a lot of HTTP GET request messages are sent to the victim web server, overwhelming its resources and bringing down its services to the legitimate clients. The solution to such attacks in traditional networks is usually implemented at the servers, but this consumes its resources which could otherwise be used to process genuine client requests. Software Defined Network (SDN) is a new network architecture that helps to deal with these attacks in a different way. In SDN the mitigation can be done using the controller without burdening the server. In this paper, we first show how an HTTP GET Flood DDoS attack can be performed on the webserver in an SDN environment and then propose a solution to mitigate the same with the help of the SDN controller. At the server, the attack is detected by checking the number of requests arriving to the web server for a certain period of time, if the number of request is greater than a particular threshold then the hosts generating such attacks will be blocked for the attack duration.