The Bittorrent Protocol, How it Works, and Legal Issues

Bittorrent technology has revolutionized how data is shared over the Internet.  It is estimated that Bittorrent traffic accounts for about 18 percent of all traffic on the Internet. The Bittorrent protocol is a cost effective way to share information across the Internet.  One example of implementation of this technology is how gaming companies use this technology to upload game updates to all of their consumers. The basic concept of the Bittorrent protocol is to download various pieces of the desired file from different peers, as well as simultaneously uploading the downloaded pieces of the file.

There are some terms that need to be understood when talking about the Bittorrent protocol.

Torrent - This is a metadata file that contains what files that are intended to be downloaded, as well as the trackers' IP address or URL.

Tracker - Think of a tracker as a Bittorrent server. The client contacts the tracker, and the tracker connects the client to various peers or seeds.

Seed - A kind of Bittorrent peer. Seeds are peers that have the complete file(s) on their hard drive.

Leecher - A kind of Bittorrent peer. Leechers are peers that are downloading from seeds or a swarm, but are not allowing their data to be uploaded.

Swarm - A collection of peers that are downloading and uploading at the same time.

Distributed Hash Table (DHT) - Think of DHT technology as a multi-computer tracker with error checking.

A popular Bittorrent client is uTorrent. uTorrent uses the DHT technology, as well as allowing the data that is being downloaded and uploaded to be encrypted. That way Internet Service Providers (ISP) aren't able to slow those transfers.

DHT works like this. Multiple computers basically create what is called an overlay network. Each computer on this network has what is called a DHT table. This table has a key with corresponding data. Usually a key is a section of the data itself as well as a way to identify the computer that actually has that file. That key is put into what is called a hash function, that determines where on the table it is going to be stored. The purpose of this is to create a more simple way to index or organize the table, as well as provide a way to do error checking. When a computer finishes downloading a section of the file, it takes the file's hash key and reverses the process. The hash key is put through the hash function to get the original key. If the original key's values matches a section of the downloaded packet, the data has no errors. If it has errors, the packet is discarded and is re-downloaded. There are so many other aspects of DHT technology. Check out reading in the bibliography to learn more.

This technology creates more of a sense of anonymity. Currently there are anonymous P2P networks that are being developed. The most predominant one is Stealth Net.

The most legal concern of this technology is pirating copyrighted material. Companies literally have departments devoted to shutting down illegal distribution of their product. One way they do this is shutting down websites that provide an index of .torrent files. The Pirate Bay is notorious for having their Legal Threats section. One valid legal argument is that a .torrent file does not contain the copyrighted material, and therefore is legal. Copyright laws are different in various countries, and therefore makes enforcing copyright infringement a gray area. There are allocations that the United States threatened trade sanctions on the Swedish government to shut down The Pirate Bay website. The RIAA and MPAA have already filed over 30,000 lawsuits. On one case, the defendant was charged $222,000 for having $23.67 worth of copyrighted music. The case is being appealed.

It is apparent that file sharing technology is revolutionizing the way the Internet is used. It will be extremely difficult to enforce copyright infringement laws on a national scale. The way this technology is being developed, is making it extremely difficult to track who is downloading and uploading what. When deciding to use this technology, you should be aware of how it works, and what are the legal consequences of being caught if you use this technology illegally.

Jon Brengle
Senior Technology Analyst
Certified A+, N+ Technician

Bibliography

“Distributed Hash Table”. Wikipedia. December 8, 2007. Wikipedia, The Free        Encyclopedia.
    December 18, 2007. <http://en.wikipedia.org/wiki/Distributed_hash_table>.

“ BitTorrent Protocol”. Wikipedia. December 17, 2007. Wikipedia, The Free         Encyclopedia.  December 18, 2007.       <http://en.wikipedia.org/wiki/BitTorrent_%28protocol%29>.

“The Pirate Bay”. Wikipedia. December 18, 2007. Wikipedia, The Free     Encyclopedia.
    December 18, 2007. <http://en.wikipedia.org/wiki/The_Pirate_Bay>.

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