Abstract-Recently, establishing a VoIP call using a P2P network instead of regular SIP-servers has been proposed; this novel approach to SIP-signaling is commonly referred to as P2PSIP and technically based on a Distributed Hash Table (DHT). P2P networks are advantageous with respect to reliability and scalability. However, securing DHTs against adversary nodes which intentionally interrupt functionality of the network remains a major research problem. In particular, even if a trusted enrollment server is used for secure identifier assignment of participating nodes, attacks on overlay routing by malicious nodes that have successfully joined the network can still severely degrade the lookup service of the DHT. To gain insight into the ability of callers to reach callees during such attacks on DHT-routing, we present the first P2PSIP implementation that enables to emulate adversary nodes as well as the injection of a large amount of lookup requests (i.e., SIPInvite requests) in an automated way. Further, we implemented several secure DHT routing algorithms and investigated their effect on the success rate of lookups and the maximum call-setup time in an infiltrated P2PSIP network. In general, our system provides the ability to analyze attacker behavior as well as future novel security techniques in an actual P2PSIP environment with comparably low effort. [10], we present the first P2PSIP system that can emulate malicious nodes. Further, our emulation setup allows the injection of large amounts of automatically generated SIP traffic (SIP-Invite messages) into the network. This enables the measurement of the corresponding success rate of reaching the desired callee as well as the maximum call-setup time while the network is under attack in an actual P2P network. In addition, we implemented secure routing techniques and evaluated their effect on lookup success in a P2PSIP network. Overall, the setup we present in this paper provides the ability to study a P2PSIP network during a Denial-of-Service (DoS) attack on the DHT-routing layer and the effect of corresponding security techniques in a real environment. How the establishment of a SIP-session can be achieved with a P2P network in principle as well as the corresponding security challenges are described in section II and III, respectively. Section IV presents the rationale that led to our emulated system and an overview of our implementation. Advanced security techniques we implemented to test their effects on lookup success in an actual P2PSIP network are introduced in section V. Experiments we conducted and the corresponding results are detailed in section VI. Section VII discusses limitations of our approach. Section VIII concludes the paper with a summary and an outlook on future work. Technically, P2PSIP replaces all servers used in regular SIP signaling for locating the callee of a phone call (or similar multimedia communications) with a Structured Overlay Network based on a Distributed Hash Table (  This full text paper was peer reviewed at the direction of IEEE Communications Society subject matter experts for publication in the IEEE "GLOBECOM" 2008 proceedings. 978-1-4244-2324-8/08/$25.00
Several secure routing techniques for P2PSIP have already been described and evaluated in an emulative study in REF .
Evaluating P2PSIP under Attack: An Emulative Study
IEEE GLOBECOM 2008 - 2008 IEEE Global Telecommunications Conference
IEEE GLOBECOM 2008 - 2008 IEEE Global Telecommunications Conference
Computer Science