In a recent study, CHOTIA Tom et al., four researchers from the University of Birmingham, attempted to check whether BitTorrent was monitored, how it was, and by whom.  They studied the two types of monitoring:

• Indirect monitoring where the copyright infringement agency does not participate to the transaction and just collects clues with not extremely convincing evidence
• Direct monitoring where the agency is part of the transaction.  in that case, the evidence is better.

For the first type of monitoring, they used six heuristics (5 that they collected from the literature and one that they created).  The conclusion is clear: many agencies are scouting the swarms.  Funnily, they spotted the French INRIA team who was making a similar study.  ( see Identifying providers and downloader in bittorrent).   Without surprise, this part of the study was conclusive.

For direct monitoring, they tried other heuristics such as checking whether the reported completion progresses or is consistent, or the duration of connection.  Once more, they detected monitoring activity.

The study presents also several interesting (but not surprising) conclusions:

• The most popular pieces of content are far more monitored than less popular.  This is logic as monitoring as a cost and who would pay for the long tail?
• When sharing a popular piece of content, the likelihood to be monitored within three hours is high.
• The block lists of supposed monitors (which are available for most popular clients) are not complete.

The definition of the heuristics is interesting.   It gives a good hint to the agencies on what they should do to become stealthier.