GEN:SID 1:2181
Message P2P BitTorrent transfer
Summary This event is generated when a BitTorrent client transfers data with
another BitTorrent peer.
Impact Possible violation of policy and abuse of network resources.
Detailed Information BitTorrent is a peer-to-peer application used for simultaneous downloads
of large files.  BitTorrent is designed to allow multiple peers to
download large files simultaneously without using extraneous bandwidth
from a centralized server.

BitTorrent peers connect to other peers for file transfer.  This rule
looks for the BitTorrent protocol header on the default BitTorrent
ports.
Affected Systems  
Attack Scenarios A user downloaded a BitTorrent client and attempts to download files
from a BitTorrent network.
Ease of Attack Unix, Windows, and MacOS clients are publicly available for BitTorrent.
Corrective Action If this is a violation of network policy, take appropriate steps to
prevent further violations.
Additional References Bittorrent Protocol Specification
http://bitconjurer.org/BitTorrent/protocol.html

Wikipedia
http://en.wikipedia.org/wiki/BitTorrent