Tracking Skype VoIP Calls Over The Internet

Peer-to-peer (P2P) VoIP calls such as those provided by Skype have been becoming popular due to their quality-of-service, free of cost, security and convenience. Skype is a distributed P2P network with no centralized call servers. Calls traverse through a myriad of possible paths before reaching to the destination and each packet is encrypted with 256 bit AES encryption. In this paper, we are particularly interested in tracing out from this entangled web of peer nodes, who has called a target subscriber or to whom the target subscriber is calling. To this end, we present a transparent packet marking scheme that not only determines the origination and destination of a call but also the path taken through various hosts in P2P networks.