BitTorrent Basics


This article was published by ComputorEdge, issue #2704, 2009-01-23, as the cover article, in both their PDF edition (on pages 6-8) and their website.

Data distribution is the very essence of the Internet. Yet there are numerous ways of distributing data over the Net. These include Hypertext Transfer Protocol (HTTP), which is how the text and images on the typical Web page are transmitted from a Web server to your computer, and viewable within your Web browser. File transfer protocol (FTP), as the name implies, is designed not for the transfer of small Web page elements, but instead for the transfer of complete files, from one server to another.

Other distribution methods have been developed, such as peer-to-peer (P2P) networking. Most of the P2P networks work as follows: Each person logged into the network is running a client application specific to that particular network. The program allows the user to make available, to anyone else on the network, any files on his computer (or all of the computers on his home network). If another user does a search within her P2P application for a file that he has made available, then the file can be copied from his computer to hers, through the network (over the Internet, of course).

Some of the better-known P2P networks are Direct Connect, FastTrack, Gnutella, and Napster, as well as some that have been shut down, but were quite popular in their time, e.g., eDonkey (a.k.a. eDonkey2000). Multiple client applications exist for each one of the P2P networks. For instance, the Gnutella network can be accessed by people running BearShare, Grokster, iMesh, LimeWire, Shareaza, and several others.

Bit by Bit

Perhaps the hottest and most promising P2P network is BitTorrent, which takes a different approach to the sharing of files: It utilizes breakthrough "file-swarming" techniques for dividing up an original digital file into pieces — known as a "torrent" — and then sharing those pieces among all the users that have requested that particular file. This is similar to the phenomenal growth of "social news" and "social bookmarking" on the Web, which rely upon the power of the opinions of many people, all over the world. Users who are making available copies of a given file are known as "seeders", while people who are downloading the file are known as "leechers". Hence the common admonition, "Please seed this file!", i.e., share it with others, rather than making it unavailable (in order to eliminate the bandwidth burden on your computer when other people request that file).

BitTorrent leverages the power of a group of users sharing pieces of a file among themselves, and by doing so greatly increases the chances that you will be able to obtain all of the pieces that compose a particular file that you want. In other words, you are downloading different sections of the same file from multiple users (in most cases), thus making the system more redundant. This is a huge improvement over traditional peer-to-peer networks that are based upon your obtaining a file from just a single user. What if that person disconnects from the Internet before the entire file has been downloaded to your computer? In that case, you end up with only the first part of a file, and not a complete one. This is quite annoying if it is a music file, and the latter portion of it has been chopped off. The situation is even worse if you are downloading an executable file, because a partial computer program won't even run.

Another advantage to BitTorrent is that the client programs are not only free to use, but they usually contain no spyware and no pop-up advertising. This is in stark contrast to the many other peer-to-peer network clients that repeatedly pop-up obnoxious advertisements — some so frequently as to make those programs unbearable. For anyone interested in trying out a BitTorrent program, there are many quality ones from which to choose. Some of the better-known names include BitComet, BitTornado, LimeWire, Shareaza, μTorrent, and Vuze (formerly known as Azureus).

Downloading using BitTorrent is generally faster than using any other P2P network, for two reasons: Instead of relying upon a single connection to the one individual who is sharing their copy of a file with you, your BitTorrent client is assembling the file from multiple users, via multiple connections — not unlike the power of parallel processing, in which two or more microprocessors split up a computational task among themselves, or the way in which a multithreaded computer program can divvy up processing steps among several threads within a single instance of the program. A second speed advantage, typically overlooked by industry pundits, is that BitTorrent users tend to be more tech savvy than those using other networks, and consequently have faster connections to the Internet, for uploading pieces of your requested file to your BitTorrent client.

A Torrent of Controversy

The use of BitTorrent for distributing files has come under the same scrutiny and attacks that have been leveled at their P2P predecessors, such as Napster and eDonkey, to name just two. That is because much of the traffic on these networks consists of music, movies, and TV shows — all protected by copyright laws, which technically are being violated through online sharing. This has naturally angered industry groups such as the Recording Industry Association of America (RIAA) and the Motion Picture Association of America (MPAA), which are trade groups that represent the recording and movie industries in the United States, respectively. Many other developed nations have similar trade organizations.

Criticism of these two organizations' activities against file sharers has been intense and unrelenting, largely because of the draconian legal actions that the organizations have taken against the people they accuse of violating copyright laws through sharing music and movies online. The RIAA has been especially active in its legal assaults against consumers, dating back to 2003. According to InfoWorld, during a 12-month period, from October 2003 to September 2004, the total number of lawsuits filed was 5,541. Less than two years later, by February 2006, the number had reached 17,587. The total amount of money won through court actions — many of which are resolved as settlements — is most likely staggering, and increasing every week.

Boycott-RIAA is one of several organizations that have been battling the RIAA, and making the public aware of the more egregious lawsuits, such as those levied against children who barely know how to use a computer, poor people who would be bankrupted by even the most modest of the settlements sought by the RIAA, and even people who don't own computers! Industry analysts have argued that the pursuit of file sharers has, on balance, been counterproductive for the music industry, because the people who share the most files also spend the most amount of money purchasing CDs and MP3s. The RIAA has apparently learned the folly of branding their customers as enemies, because in December 2008, they halted all lawsuits against individuals. Sadly, their new approach is to try to convince Internet service providers (ISPs) to disconnect anyone sharing music files.

The spirited ongoing battle between file sharers and copyright enforcers, can be followed in the online media. Those siding with file sharers can read the latest battle reports on various websites, such as TorrentFreak, which makes available up-to-date news, recommended torrent sites, and other relevant information. Those siding with copyright enforcers can read press releases from the music and movie industry groups — assuming that the individual's ISP does not accidentally disconnect them for alleged file sharing.

Unfortunately, all of this legal controversy has given BitTorrent a bad name, and besmirched the countless uses of the technology that are completely legal. For instance, a growing number of companies are distributing their products as torrents — choosing to ride the wave of BitTorrent sharing, instead of trying to hold back the wave. For instance, new versions of open source software, such as Linux, are perfect candidates for dissemination as torrents.

So if you would like to experience the remarkable resource known as BitTorrent, be sure to try it now, while you still can, before it gets snuffed out by government or industry.

Copyright © 2008 Michael J. Ross. All rights reserved.

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