BitTorrent
From wsuwiki
Contents |
Overview
BitTorrent is a peer-to-peer (P2P) file sharing protocol that allows multiple computer users to connect to one another and share a file amongst themselves. It is also the name of one of the major BitTorrent download clients. Although P2P file sharing protocols and clients have been around for quite a while, i.e. Napster and KaZaA, the way BitTorrent allows sharing is unique. Like previous P2P protocols, BitTorrent allows users to download files that are hosted by computers connected to the client through the Internet. However, whereas previous protocols only allowed users to connect to the hosting computer to download the file; BitTorrent allows users to connect to everyone that has that specific file as well as everyone that is currently in the process of downloading it. This means that users are uploading the parts of the file they have to other users while they are still in the processes of downloading the rest of the file. Before BitTorrent download speeds from P2P clients were limited to the upload speed of the computer that was hosting the file. With BitTorrent a downloader is often limited by their own download speed if the file is being shared by enough users at once. It should be noted though that if a file is not being shared by very many people then the possible download speed may not be very high.[1]
Torrent
In order to connect with peers through a BitTorrent client, users must first download a file known as a torrent. A torrent is a small metadata file, usually no larger than a few hundred kilobytes, that contains information on the data that the user wants to download. There are numerous sites on the Internet that allow people to upload torrent files that can be download and opened with a BitTorrent client. Once opened the client will use the information in the torrent file to connect to other users through the use of a tracker and begin sharing the file.[2]
BitTorrent Clients
A BitTorrent client is a program that allows users to connect to one another through the use of the BitTorrent protocol[3]. The client can open and in the case of some clients, create torrent files. Once the files are opened it manages the uploading and downloading of the files. It also periodically queries the tracker in charge of the torrent to find out who is currently sharing the file so it can connect to other peers as needed. Many clients also have their own search engines to allow users to search for torrents from the client instead of having to go to a torrent website. There are many different BitTorrent clients with BitTorrent being the most well known. A list of some of the more popular clients is given below:
• Vuze (formerly Azureus )
• BitComet
• μTorrent
Terminology
The definitions below are for some of the more commonly used terms used by BitTorrent clients and users. Knowing these terms can be somewhat helpful for people who use or plan to use BitTorrent.[4]
Peer
A computer that you connect to through the use of your client in order to download a file is often known as a peer if they do not currently have the entire file downloaded.
Leechers
Leechers are peers that download torrents while uploading as little as possible. Leechers can accomplish this either by telling the BitTorrent client not to upload at all or by downloading special clients designed specifically for leeching.
Seeder
Whereas a peer is another computer that is still downloading the same file as you, a seeder is a computer that already has downloaded the complete file. Unless specified a BitTorrent client will begin seeding a torrent after it has completed downloading it. Closing the torrent or specifically telling the client not to seed when the download completes will stop your computer from seeding a torrent.
Swarm
A swarm consists of all the users that are currently connected to a certain file. Both seeders and peers are listed in the swarm.
Tracker
A tracker is the server on the Internet that contains all the information about a torrent that is being downloaded. It is what gives a client information about other users that are currently uploading and downloading a particular torrent so that the client can connect to them.
Share Ratio
Your share ratio is a measurement of your uploading and downloading activity. Users with a share ratio of 1.0 have uploaded the same amount of data as they have downloaded. Less than 1.0 means they have downloaded more than they uploaded. Some torrent sites will only allow users to download their torrents if they’re share ratio is above a certain level.
Lack of Anonymity
One major disadvantage of the BitTorrent protocol is that it lacks anonymity. When a user’s BitTorrent client connects to a tracker to get a list of peers, the client gives the tracker the user’s IP address. The IP address can then be seen by anyone using the same tracker. For users that are legitimately downloading legal files this is perhaps not such a big deal; though some users may disagree where their privacy on the Internet is concerned. However for users that are illegally downloading copyrighted materials this can be a bit of a problem. ISPs like Comcast have been known to use the tracker information to send cease-and-desist orders to owners of IP addresses that they have found to be sharing copyrighted material. Usually this will contain a threat of cancellation of service for offenders who do not remove the copyrighted materials from their system within a certain time frame.[5]
Current Issues
Since its inception, BitTorrent has been the subject of controversy. Like previous P2P file sharing clients, BitTorrent makes it very easy for users to illegally share copyrighted materials. Due to this, BitTorrent has been met with mixed reactions from organizations that create content such as music and movies that can easily be distributed online. [6]
Proponents
There are quite a few companies and individuals that have started using BitTorrent to distribute their content on the Internet. Distribution through BitTorrent can help save distributers money that they would otherwise have to spend on high bandwidth connections and dedicated servers. This is due to the fact that they are simply acting as a seeder for a torrent that their customers can share amongst themselves as it is downloaded. BitTorrent can be especially helpful to independent distributors such as independent film makers that don’t have a lot of capital to invest in a dedicated distribution system.
Two examples of companies that use BitTorrent for the distribution of content are Blizzard Entertainment and Canonical Ltd. Blizzard uses their Blizzard Downloader client to distribute copies of its MMORPG, World of Warcraft, as well as game updates to its customers. Canonical Ltd. is the name of the company behind the development and distribution of the popular Linux-based operating system, Ubuntu. Blizzard uses the Blizzard Downloader for almost all its updates but does host direct downloads on its site for users who can't download with BitTorrent. Canonical on the other hand mostly uses a system of servers across the globe from which users can download Ubuntu directly, but they also give the option to download it through BitTorrent.
Opponents
Conversely many content producing organizations are vehemently opposed to BitTorrent for the same exactly reason that many have utilized it; the ease of content distribution. However, whereas the proponents readily use BitTorrent because it helps them lower costs, the opponents are against it because it is helping them lose money. Specifically it is causing them to lose money due to pirating of their copyrighted content. Organizations such as the RIAA and MPAA have been against the use of BitTorrent since the beginning and over the years they have actively sought out and prosecuted both BitTorrent users that have pirated copyrighted material and the owners of websites that allow their users to list torrents that contain copyrighted material.
Another group opposed to BitTorrent is Internet Service Providers. ISPs are opposed to BitTorrent due to the shear amount of traffic that its users take up in an ISPs network which can slow down the speed of non-BitTorrent customers connections. In an effort to cut down on the amount of traffic created by BitTorrent users, some ISPs have actively taken in part in throttling (slowing down) the connection of customers using BitTorrent. This has met with a lot of outrage from the Internet community because it goes against the principles of network neutrality which is popular with many Internet users.
The Pirate Bay
One famous example of a websites owners being prosecuted for allowing users to uploading torrents for copyrighted content on their sight is The Pirate Bay. The Pirate Bay, one of the most well known and used torrent tracking sites, had their company headquarters raided in May of 2006 by Swedish authorities for IP information from their tracking servers concerning the distribution of copyrighted material. Charges were filed against the four owners in January 2008 for the accessory to crimes against copyright law. Finally on March 3, 2009, nearly three years after their servers were first raided, the owners were convicted and sentenced to one year in prison each as well as 30 million Swedish kronor (roughly $3.6 million USD) which they are jointly responsible for. They have since appealed the conviction and are still waiting a verdict.[7]
References
Bittorrent - Bit Torrent Terms and Definitions. (n.d.). Retrieved October 24, 2009, from Vlad44: http://www.vladd44.com/torrent/terms.php
Comparison of BitTorrent Clients. (2009, October 23). Retrieved October 24, 2009 , from Wikipedia: http://en.wikipedia.org/wiki/Bittorrent_clients
jonfung. (2009, March 13). Security Review - BitTorrent. Retrieved October 24, 2009, from UW Computer Science Research and Course Blog: http://cubist.cs.washington.edu/Security/2009/03/13/security-review-bittorrent/
Ricknäs, M. (2009, April 17). The Pirate Bay Four Found Guilty. Retrieved October 24, 2009, from PC World: http://www.pcworld.com/article/163317/the_pirate_bay_four_found_guilty.html
soulxtc. (2008, April 2). What is BitTorrent? A Beginner's Guide. Retrieved October 24, 2009, from ZeroPaid: http://www.zeropaid.com/news/9378/what_is_bittorrent_a_beginners_guide/
You Are Not Anonymous. (2004, April 8). Retrieved October 24, 2009, from DSLReports: http://www.dslreports.com/shownews/41933