Tolerating Denial-of-Service Attacks Using Overlay Networks - Impact of Overlay Network Topology

Proxy-network based overlays have been proposed to protect Internet Applications against Denial-of-Service (DoS) attacks by hiding an application’s location. We study how a proxy network’s topology influences the effectiveness of location-hiding. We provide a general analysis of system dynamics under attack, and study how the speed of attack, speed of defense, and proxy network topology affect these dynamics. Our analysis characterizes when proxy networks are robust against attacks (attackers’ impact can be quickly and completely removed), and when they are vulnerable to attacks (attackers’ impact cannot be completely removed). We present a general set of metrics for proxy network topologies which can be applied to evaluate them with respect to robustness and vulnerability. We apply these metrics and analysis to a range of popular overlay network topologies, showing that the Chord [18] used for location-hiding in [27, 19], is not a good choice, and that topologies such as CAN [20] are a much better topology for DoS resistance and location-hiding. In general proxy networks with lower vertex degrees and balanced distribution of connectivity have better properties. Our results provide a set of sound design principles for proxy network topologies for location-hiding and DoS-resistance.