On the effectiveness of secure overlay forwarding systems under intelligent distributed DoS attacks

In the framework of a set of clients communicating with a critical server over the Internet, a recent approach to protect communication from distributed denial of service (DDoS) attacks involves the usage of overlay systems. SOS, MAYDAY, and I3 are such systems. The architecture of these systems consists of a set of overlay nodes that serve as intermediate forwarders between the clients and the server, thereby controlling access to the server. Although such systems perform well under random DDoS attacks, it is questionable whether they are resilient to intelligent DDoS attacks which aim to infer architectures of the systems to launch more efficient attacks. In this paper, we define several intelligent DDoS attack models and develop analytical/simulation approaches to study the impacts of architectural design features of such, overlay systems on the system performance in terms of path availability between clients and the server under attacks. Our data clearly demonstrate that the system performance is indeed sensitive to the architectural features and the different features interact with each other to impact overall system performance under intelligent DDoS attacks. Our observations provide important guidelines in the design of such secure overlay forwarding systems.