According to Bit Torrent Inc, a milestone 150 million active users was reached by Bit Torrent in January this year. Wikipedia says this makes Bit Torrent more used than YouTube and Facebook combined. With such a large amount of internet traffic (consisting of both legal and illegal activity), you might be unsurprised that copyright enforcement agencies have a keen interest in keeping their eyes on users’ IP addresses for potential breaches. What we haven’t heard much about is the way in which enforcement agencies conduct such monitoring.

A report published on 5 September this year by a team at the University of Birmingham’s School of Computer Science in the UK identified 1,139 IP addresses which were likely to be monitoring users of Bit Torrent around the world. The IP addresses belonged to known copyright enforcement agencies such as Checktor (a company which offers commercial Bit Torrent monitoring services) and Peer Media Technologies (which monitors the ebook and movie torrents of the Harry Potter series). In conducting their research, the scientists were careful not to download any infringing content themselves.

The most common method used in the industry is "indirect monitoring", which relies on indirect clues about a user’s sharing activity – however, this has been shown to result in false positives (with innocent IP addresses such as printers being sent cease-and-desist letters). The report showed that copyright enforcement agencies concentrate resources on popular content, with movie and music torrents being the most carefully watched. The report suggested novel features to improve the monitoring techniques that are currently used by enforcement agencies – but, taking a neutral stance in the battle between Bit Torrent users and copyright enforcers, it also gives users information on how to detect the detectors.