Simulation study of application layer DDoS attack

In this digital era, Internet has become the most widely used media of communication. Numerous critical services like e-commerce, social media, online banking are based on the Internet, so non-availability of Internet may lead of financial, social and legal implications. DDoS attacks are the most serious attack that hampers the availability of Internet. Their major aim is to deny the services of the legitimate users. The current solutions of DDoS defence are not able to handle these types of sophisticated attacks. Application Layer DDoS(AL-DDoS) attack in-turn makes this problem even more challenging. Because in AL-DDoS attacks, a genuine connection is established with the server by the legitimate clients that make it difficult to differentiate the attacker and the normal client. This paper aims to study the impact of the application layer DDoS attacks against web services using web cache model available in NS2 simulator. The attack is launched on the server requests handling capacity so that legitimate users wont get the required services. Various performance metrics like transaction throughput, legitimate transactions drop, server queue utilization by legitimate, successful HTTP transactions, Transaction survival ratio etc. are calculated to measure the impact of the attack.