Using Overlay Networks to Resist Denial-of-Service Attacks

Proxy-network based overlays have been proposed to protect Internet applications against Denial-of-Service (DoS) attacks by hiding an application’s location. We develop a formal framework which models attacks, defensive mechanisms, and proxy networks. We use the framework to analyze the general effectiveness of proxy network schemes to protect applications. Using our formal model, we analytically characterize how attacks, defensive schemes, and proxy network topology affect the secrecy of application location and general resource availability. Our results provide guidelines for the design of proxy networks; the formal framework provides a tool to study problems in this area. Our analysis shows that proxy networks are a feasible approach to prevent infrastructure-level DoS attacks. Proxy network depth and system reconfiguration are the keys to achieving location hiding. Proxy network topology also has an important impact -rich connectivity in the proxy network, a virtue in other circumstances, reduces effectiveness in location hiding. Finally, to avoid resource depletion, reactive resource recoveries are insufficient; proactive schemes are needed.