Difference between revisions of "BitTorrent"

Revision as of 20:37, 18 December 2011

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BitTorrent is the peer-to-peer file sharing protocol used by many P2P clients and it's also called Mainline by web developers. It was designed by computer programmer Bram Cohen in April 2001 ^[1] . The first version of the BitTorrent client was released on July 2, 2001, and now it is available for Mac OS X and Microsoft Windows.

BitTorrent Logo

Introduction

BitTorrent is the file sharing client that is shared between peers. The protocol permits users to connect across the internet and share certain files with other users. BitTorrent is one of the most prevalent protocols for moving big files, and it has been estimated that it makes up to 70% of all internet traffic.

Torrent

A torrent file is the basis of the peer-to-peer connection in that it holds a description of the location of the various pieces of the file that is being shared. The torrent is not the actual file being shared however, it is just a mapping of the smaller portions. Torrents are hosted by third parties online but made easily accessible and searchable by BitTorrent clients and torrent-specific search engines.

Mechanics

When a user downloads a torrent file, it contains a hash of the files to be downloaded. It also contains a list of servers, known as trackers, that the user can connect to in order to find BitTorrent users which are seeding the necessary files. After the user connects and receives the list of users sharing the file, the user's BitTorrent client will connect to these users. The aggregate of all the connections is known as the user's swarm. The client will begin by sending out requests to the swarm in order to obtain a list of which pieces are available to download, then it will make requests for those files. In turn, the swarm will begin sending its own requests for pieces which the user's client can then reciprocate. The process of downloading a file using a BitTorrent client is known as leeching. Once the files are finished downloading, the user can remain in the swarm and continue sharing pieces, also known as seeding. It is important for a torrent to always have at least several users who are seeding a file, or else the torrent will die. The torrent dies when new users are unable to download any pieces at all, or are stuck at a certain percentage and unable to obtain any further pieces.

Sharing

In regards to the BitTorrent protocol, uploading or sharing pieces is commonly referred to as seeding. When a user downloads without seeding, they are said to be leeching. Torrent files are designed so that users may seed portions before they have downloaded the entire file, meaning others can download parts of the file from the user, even before the user has finished downloading it. The fact that only portions of a file can be downloaded from multiple sources is a large factor in the popularity of BitTorrent applications. Since this method of file sharing aggregates pieces of files from many different locations, it also magnifies the risks and responsibilities associated with file sharing.

Seeding

Seeding is a way of reciprocating the effort of the users who originally made the files available. The thought is that they are passing the proverbial torch to you, so that they can move on to sharing other files. This results in a domino effect that increases the files' availability and results in faster downloads for all.^[2] Most BitTorrent clients limit a user's download speed in correspondence with the frequency and capacity of their uploading. This reduces the amount of leechers , users who download files but do not contribute to the array of uploading hosts, by making contributions imperative to the system.

Illustration of the process in which BAYU detects and notifies uploading users.

The previous banner for the University of Michigan BAYU initiative.

• Be Aware You're Uploading or more commonly referred to as BAYU is an initiative adopted by many large universities or organizations that actively seek ways in which to reduce the risk of affiliated persons becoming involved in piracy lawsuits. At the University of Michigan Ann Arbor, it alerts staff and students to their uploading by means of an email notification until the system determines that the affiliate is aware of their actions. At this particular school, BAYU is not a disciplinary entity and is not responsible for handling any litigation regarding illegal file sharing. It is merely a courtesy service implemented in direct response to the large numbers of users on extensive networks that are unaware that they are currently uploading content regardless of the legality of such content. At the University of Michigan, students and staff have the ability to opt-out of having any future BAYU notifications.^[3]
  • "Approximately 400 pre-litigation settlement letters sent out by RIAA against students each week"^[3]
  • "Average settlement amount is about $3000"^[3]

Throttling remains the most effective method for controlling internet users whose utilize the BitTorrent protocol.

ISP Throttling Internet Service Providers(ISP) have the ability to control exactly how much of their bandwidth is allotted for certain customer tasks, much like the throttle on a simple engine. The concept of throttling bandwidth by ISPs is nothing new and is done for reasons such as upholding contractual partnerships with certain websites as well as limiting the advantages of BitTorrent.

• Research published by Measurement Lab revealed statistics involving several large ISPs and their throttling procedures:^[4]
  • After an FCC investigation and being ordered to stop placing data caps on ports used for BitTorrent, Comcast is down to throttling only 3% of traffic from nearly 50% in early 2008^[4]
  • Comcast remains the ISP in the United States that limits BitTorrent traffic the least
  • Clearwire remains the most throttled network with approximately 17% of all traffic throttled
  • Canadian ISP Rogers limits 78% of all BitTorrent traffic
  • Videotron limits only 3% of Canadian traffic

Legal Use

File sharing through the use of BitTorrent applications is currently legal, and is widely used by many organizations due to the benefit of having a large population of users willing to host files. This allows such organizations to cut costs by not hosting large files for large customer bases, and in turn dramatically increases the speed of downloads due to multiple hosts being utilized simultaneously. BitTorrent is growing extremely popular with Open Source Software as well as with the commercial software industry.

• Blizzard Entertainment is just one example of a large commercial software company that distributes its extremely large files via BitTorrent. The reason downloading software that was originally intended to be shared via BitTorrent is currently legal is that companies often use activation or subscription codes in order to continually use the product. Without an active account o subscription, the downloaded software is useless.

Illegal Use

The use of such applications in order to share material protected under copyright is illegal. Despite being illegal, the use of torrents is constantly increasing due to the extreme ease and low risk with which one can obtain copyrighted material.

• As of Fall 2011, Voltage Pictures is currently involved in lawsuits against approximately 2,300 defendants in direct response to their use of BitTorrent clients to illegally share copies of the movie The hurt Locker. Although large numbers of IP addresses are being added to dismissed from Voltage's long list of defendants on a daily basis, a large number of their original 24,583 defendants have been dismissed. The list of IP addresses includes clients from most major service providers, some of which, have yet to be served. Settlements with Voltage Pictures are estimated to cost thousands of dollars.^[5]

• In October 2011 Torrent Freak compiled a list of the top ten illegally downloaded movies using the BitTorrent protocol:^[6]

Breakdown of torrents by filetype. Provided by ProdiGeek

Rank	Movie	Downloads	Worldwide Grosses
1	Avatar(2009)	21 million	$2,782,275,172
2	The Dark Knight(2008)	19 million	$1,001,921,825
3	Transformers(2007)	19 million	$709,709,780
4	Inception(2010)	18 million	$825,408,570
5	The Hangover(2009)	17 million	$467,483,912
6	Star Trek(2008)	16 million	$385,680,446
7	Kick-Ass(2010)	15 million	$96,188,903
8	The Departed(2006)	14 million	$289,847,354
9	The Incredible Hulk(2006)	14 million	$263,427,551
10	Pirates of the Caribbean: At World's End(2007)	14 million	$963,420,425

Ethical Implications

There are a variety of ethical implications surrounding the use of BitTorrent applications.

Copyright

Although these torrenting applications are currently legal, it is illegal to share material that is protected under copyright. This bodes the questions whether or not users will abide by these loosely established laws. The BitTorrent software grants users the abilities to access data that they might not have permission to access and thus there are a variety of ethical concerns surrounding the use of torrenting applications. Is it the user's responsibility to properly use the software the way it was intended to be used? Should they be accountable if they abuse the software they are presented with? Or should the companies that produce the software be the ones held responsible when their software is misused? It is a tough and seemingly impossible question to fully resolve, but will most definitely be a topic of debate as torrenting continues to have more of an impact in today's society.

Recently, Congress has been discussing a bill called the SOPA Act or the Stop Online Piracy Act that, among various other things, will raise the power of law enforcement on technologies that support pirating, including BitTorrent. The bill marks a strong line about the ethics of pirating, indicating that it is morally wrong to share material. Companies like Google and Facebook have debated the merits of the bill.^[7]

File Sharing Culture

Torrenting has developed an entire culture around the ideas of reciprocity and the common good, an area of study which is common among the social sciences. Without generosity, torrenting communities and trackers would inevitably become obsolete. Specifically, if most users were to only leech files and never seed them, the file swarms would quickly dissolve and the torrents would slowly die. Over time, this would lead to a reduction in both the quantity and quality of available material. There are not many ways to force users to upload the torrents that they have downloaded, but one way that has seemed effective is by using private tracking websites.

Private trackers are communities where users have to be invited by current members. Most private trackers are very exclusive, requiring an invitation, in order to preserve the integrity inside the community since every user is vouched for by the person who invited them. These invitations are usually handed out to trusted users who have achieved a certain status inside the community, which is evaluated based on their overall contributions to the community. The only time that these trackers hold open registrations is when they perform mass deletions of accounts that have not been active, and certain highly-exclusive trackers do not ever have open registrations. In order to make sure that all users upload the torrents that they download, these trackers maintain enforced sharing ratios for all users, where the ratio is defined as amount uploaded divided by the amount downloaded, usually in megabytes or gigabytes. Most private trackers enforce a threshold, usually .60 or in the worst cases 1.00, that users must maintain their ratio above in order to continue downloading torrents. In addition to this rule, private trackers require the user to seed the downloaded torrent for at least one full copy (the size of the file) or for a certain amount of time, which varies amongst different trackers. If a user falls under the threshold that the tracker has set, they will go on "ratio watch," or in other words, they will be warned that their ratio is too low and that they must increase it. Users are generally given a certain amount of time to increase their ratio above the threshold before their account is suspended or banned. Thus, if a user only leeches files and never seeds them, their ratio will consistently fall under the threshold and will eventually lead to a ban. Some private trackers have "free leech" torrents where the download does not count towards your ratio but any subsequent amount that is uploaded does. This allows users to build up their ratio.

See Also

• File Sharing
• Digital Piracy
• Stop Online Piracy Act
• Protect IP Act
• Internet Control
• Digital Copyright Compliance

References

1. ↑ http://mozy.com/infographics/a-history-of-bittorrent/
2. ↑ http://www.utorrent.com/help/guides/beginners-guide
3. ↑ ^{3.0 3.1 3.2} http://www.rfrost.people.si.umich.edu/courses/SI110/slides/bayu_si110.pdf
4. ↑ ^{4.0 4.1} http://torrentfreak.com/bittorrent-throttling-internet-providers-exposed-111020/
5. ↑ http://torrentfreak.com/90-of-defendants-dismissed-from-record-breaking-bittorrent-lawsuit-110930/
6. ↑ http://torrentfreak.com/top-10-most-pirated-movies-of-all-time-111012/
7. ↑ http://www.washingtonpost.com/stop-online-piracy-act-sopa-sparks-backlash-from-facebook-google/2011/11/16/gIQAnaSOSN_story.html

External Links

• BitTorrent's Website
• BitTorrent's Wikipedia Page

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