1 The arms race between copyright agencies and P2P users is an ongoing and evolving struggle. On the one hand, content providers are using several techniques to stealthily find unauthorized distribution of copyrighted work in order to deal with the problem of Internet piracy. On the other hand, P2P users are relying increasingly on blacklists and anonymization methods in order to avoid detection. In this work, we propose a number of techniques to reveal copyright monitors’ current approaches and evaluate their effectiveness. We apply these techniques on data we collected from more than 2.75 million BitTorrent swarms containing 71 million IP addresses. We provide strong evidence that certain nodes are indeed copyright monitors, show that monitoring is a world-wide phenomenon, and devise a methodology for generating blacklists for paranoid and conservative P2P users.