Phalanx: Withstanding Multimillion-Node Botnets

Large-scale distributed denial of service (DoS) attacks are an unfortunate everyday reality on the Internet. They are simple to execute and with the growing prevalence and size of botnets more effective than ever. Although much progress has been made in developing techniques to address DoS attacks, no existing solution is unilaterally deployable, works with the Internet model of open access and dynamic routes, and copes with the large numbers of attackers typical of today’s botnets. In this paper, we present a novel DoS prevention scheme to address these issues. Our goal is to define a system that could be deployed in the next few years to address the danger from present-day massive botnets. The system, called Phalanx, leverages the power of swarms to combat DoS. Phalanx makes only the modest assumption that the aggregate capacity of the swarm exceeds that of the botnet. A client communicating with a destination bounces its packets through a random sequence of end-host mailboxes; because an attacker doesn’t know the sequence, they can disrupt at most only a fraction of the traffic, even for end-hosts with low bandwidth access links. We use PlanetLab to show that this approach can be both efficient and capable of withstanding attack. We further explore scalability with a simulator running experiments on top of measured Internet topologies.