Bit Torrent

 

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BitTorrent is a communications protocol of peer-to-peer file sharing ( “P2P”) Which is used to Distribute data and electronic files over the Internet. BitTorrent is one of the Most common Protocols for transferring large files, Such as digital video files Containing TV shows or video clips or digital audio files Containing songs. Peer-to-peer networks collectively have been estimated to account for approximately 43% to 70% of all Internet traffic (Depending on location) as of February 2009. [1] In November 2004 BitTorrent Was Responsible for 25% of all Internet traffic. [2] As of February 2013, BitTorrent Was Responsible for 3:35% of all bandwidth Worldwide, more than half of the 6% of total bandwidth dedicated to file sharing. [3]

To Receive files or object, a person uses a BitTorrent “client” on his Internet-connected computer. A BitTorrent client is a computer program implements the BitTorrent protocol That. Clients include μTorrent, Xunlei, Transmission, qBittorrent, Vuze, Deluge, and BitComet. BitTorrent trackers Provide a list of files available for transfer, and Allow the client to find seeds known as peer WHO users may transfer the files.

Programmer Bram Cohen, a University at Buffalo student Former [4] Designed the protocol in April 2001 and released the first version available on 2 July 2001 [5] and the Most recent version in 2013. [6] BitTorrent Clients are available for a variety of computing platforms and operating systems Including released an official client by BitTorrent, Inc.

As of 2013, the BitTorrent has 15-27 million concurrent users at any time. [7] As of January 2012, BitTorrent is utilized by 150 million active users. Based on this figure, the total monthly number of BitTorrent users may swear estimated to more than a quarter of a billion.
The BitTorrent protocol Can Be Used to Reduce the server and network impact of Distributing large files. Rather than downloading a file server from a single source, the BitTorrent protocol Allows users to join a “swarm” of hosts to upload to / download from Each other simultaneously. The protocol is an alternative to the older single source, multiple sources mirror technique for Distributing data, and Can Effectively work with over lower bandwidth networks. Using the BitTorrent protocol, basic Several computers, Such as home computers, can replace the while efficiently servers Distributing large files to Many recipients. This helps lower bandwidth usage Also Prevent large spikes in online traffic in a Given Area, keeping Higher speeds for all Internet users in general, Regardless of Whether or Not They use the BitTorrent protocol. A WHO user wants to upload a file first Creates a small torrent file descriptor That broke the Distribute by conventional Means (web, email, etc.). They said Itself make the file available through a BitTorrent node acting as a seed. Those with the torrent file descriptor Can give it to BitTorrent developer’s own Nodes, qual-acting as Peers or leechers-download it by connecting to the seed and / or other Peers (see diagram on the right).

The file is being distributed segments called Divided Into pieces. As Each peer receives a new piece of the file it Becomes a source (of That piece) for other Peers, Relieving the original seed from having to object to That piece Wishing Every computer user or a copy. With BitTorrent, the task of Distributing the file is shared by WHO Those want it; it is entirely Possible item for the seed to only a single copy of the file and Eventually Distribute Itself to an unlimited number of Peers. Each piece is protected by a cryptographic hash descriptor contained in the torrent. [6] This ensures That any modification of the piece Can Be reliably detected, and THUS prevents Both accidental and malicious modifications of any of the pieces Received at other Nodes. If a node starts with an authentic copy of the torrent descriptor, it Can Verify the authenticity of the Entire file it receives.

Pieces are downloaded Typically non-sequentially and are rearranged Into the correct order by the BitTorrent Client, Which monitors Which pieces it needs, and it has qual pieces and Can upload to other Peers. Pieces of the Same size are throughou a single download (for example a 10 MB file may swear transmitted as 1 MB ten or forty pieces or 256 KB pieces). Due to the nature of this approach, the download of any file Can Be halted at any time and swear resumed at a later date, without the loss of information downloaded Previously, Which in turn makes me BitTorrent Particularly useful in the transfer of larger files. This Also Enables the client to readily available Seek out pieces and removed immediately say, Rather than halting the download and waiting for the next (and possibly unavailable) piece in line, the overall qual Typically reduces the time of the download. Once a peer has downloaded a file Completely, it Becomes an additional seed. Peers from this eventual transition to seeders determines the overall “health” of the file (as Determined by the number of times a file is available in Its complete form).

The distributed nature of BitTorrent Can lead to a flood-like spreading of a peer computer file throughou Many Nodes. As more Peers join the swarm, the likelihood of a Successful Completely removed by any Particular node increases. Relative to traditional Internet distribution Schemes, this Permits a significant reduction in the original distributor’s hardware and bandwidth resource costs. Distributed downloading Protocols in general Provide redundancy Against system Problems, Reduce Dependence on the original distributor [9] and Provide sources for the file Which are Generally transient and therefore harder to trace by Those WHO Would block distribution compared to the Situation Provided by limiting availability of fixed the file to a host machine (or Even Several).

One example of BitTorrent Such being used to Reduce the distribution cost of file transmission is in the BOINC Client-Server system. If a BOINC distributed computing application needs to be updated (or Merely sent to a user) Can it do so with little impact on the BOINC Server.
A BitTorrent client is any program That implements the BitTorrent protocol. Each client is Capable of Preparing, Requesting, and transmitting any type of computer file over a network, using the protocol. A peer is any computer running an instance of a client. To share a file or group of files, a peer first Creates a small file called a “torrent” (e.g. MyFile.torrent). This file contains metadata about the files to be shared and about the tracker, the computer file That coordinates the distribution. That Peers want to download the file first must Obtain a torrent file for it and connect to the tracker SPECIFIED, say Which Tells Peers from other qual to download the pieces of the file.

Both though ultimately transfer files over a network, download a BitTorrent download differs from a classic (as is typical with an HTTP or FTP request, for example) in Several Ways fundamental:

BitTorrent Makes Many small data requests over IP connections to Different Different machines, the while classic Typically downloading is made via a single TCP connection to a single machine.
BitTorrent downloads in a random or in a “rarest-first” [11] That approach ensures high availability, classic While downloads are sequential.
Taken together, BitTorrent Allow These Differences to Achieve much lower cost to the content provider, Higher much redundancy, and much Greater Resistance to abuse or to “flash crowds” than regular server software. Howevera, this protection, theoretically, comes at a cost: downloads Can take time to rise to full speed Because it may take time for enough peer connections To Be Established, and it may take time for a node to Receive Sufficient data to Become an Effective uploader. This contrasts with regular downloads (Such as from an HTTP server, for example) that, the while more vulnerable to overload and abuse, rise to full speed very Quickly and Maintain this speed throughou. In general, BitTorrent’s non-contiguous download methods have prevented it from Supporting progressive download or “streaming playback”. Howevera, comments made by Bram Cohen in January 2007 [12] suggest That streaming torrent downloads eu Will soon commonplace and ad supported streaming [13] Appears to Be The Result of Those comments. In January 2011 Cohen demonstrated an early version of BitTorrent streaming, the feature Was Saying Projected To Be available by summer 2011. [14] As of 2013, this new BitTorrent streaming protocol is available for beta testing.

The peer file Distributing a date treats the file as a number of identically sized pieces, usually with byte sizes of a power of 2, and Typically between 32 kB and 16 MB Each. The peer Creates a hash for Each piece, using the SHA-1 hash function, and records it in the torrent file. Pieces with sizes Greater than 512 kB Will Reduce the size of a torrent file for a very large payload, soft is claimed to Reduce the Efficiency of the protocol. [16] When another peer later receives a piece Particular, the hash of the piece is compared to the hash recorded the piece to test That is error-free. [6] Peers That Provide a complete file are called seeders, and the peer Providing the initial copy is called the initial seeder. The Exact information contained in the torrent file depends on the version of the protocol BitTorrent. By convention, the name of a torrent file has the suffix .torrent. Torrent files have an “announc” section, Which specifies the URL of the tracker, and an “info” section, Containing (Suggested) names for the files, Their Lengths, the piece length used, and a SHA-1 hash code for Each piece, all of Which are used by Clients to Verify the Integrity of the data They Receive. Though SHA-1 has shown signs of cryptographic Weakness, Bram Cohen Consider the risk does not big enough for a backward incompatible change to for example SHA-3. [17]

Typically Torrent files are published on websites or elsewhere, and registered with at Least one tracker. The tracker maintains lists of the Clients currently the participating in the torrent. [6] Alternatively, in a trackerless system (decentralized tracking) Acts as a peer Every tracker. Azureus Was the first [18] Such BitTorrent client to Implement a system through the distributed hash table (DHT) method. An alternative and incompatible DHT system, known as Mainline DHT, was released in the mainline BitTorrent client three weeks later (though it HAD been in development SINCE 2002) [18] and subsequently Adopted by the μTorrent, Transmission, rTorrent, KTorrent, BitComet, Clients and Deluge.

Was Adopted After the DHT, a “private” flag – analogous to the broadcast flag – Was Introduced unofficially, telling Clients to RESTRICT the use of decentralized tracking Regardless of the user’s desires. [19] The flag is intentionally placed in the info section of the torrent That’s so can’t swear disabled or removed without changing the identity of the torrent. The Purpose of the flag is to Prevent torrents from being shared with Clients That would not have access to the tracker. The flag Was requested for inclusion in the official specification in August 2008, the soft has not been accepted yet. [20] Clients have IGNORED the private That Were flag banned by Many trackers, discouraging the practice.
Users find a torrent of interest, by browsing the web or by other Means, download it, and open it with a BitTorrent client. The client Connects to the tracker (s) SPECIFIED in the torrent file, from Which it receives a list of Peers currently transferring pieces of the file (s) SPECIFIED in the torrent. The client Connects to Those Peers to Obtain the Various pieces. If the swarm contains only the initial seeder, the client Connects directly to it and begins to request pieces. Clients incorporate Mechanisms to optimize developer’s download and upload rates; for example broke the download pieces in a random order to Increase the Opportunity to exchange data, Which is only two Peers have f Possible Different pieces of the file.

The Effectiveness of this data exchange depends largely on the policies to Determine That Clients use to Whom to item data. Clients may prefer to item Peers That item data to date back to say (a “tit for tat” exchange scheme), Which encourages fair trading. But strict policies Often Result in suboptimal Situations, Such as Peers are joined Newly When Unable to Receive any data Because They do not have any pieces yet to trade themselves or Peers When two with a good connection between data exchange do not mean simply Because neither of say takes the initiative. To counter These effects, the official BitTorrent client program uses a mechanism called “Optimistic unchoking”, whereby the client reserve a portion of Its available bandwidth for sending pieces to random Peers (not necessarily known good partners, so called preferred Peers) in Hopes of Discovering even better partners and to Ensure That newcomers get a chance to join the swarm. [22]

Although “swarming” scales well to tolerate “flash crowds” for popular content, it is less useful for unpopular or niche market content. Peers arriving after the initial rush Might find the content unavailable and Need to wait for the arrival of a “seed” in order to complete developer’s downloads. The seed arrival, in turn, may take long to happen (this is TERMEDIA the “promotion seeder problem”). Since maintaining seeds for unpopular content entails high bandwidth and administrative costs, this runs counter to the Goals of BitTorrent publishers That value as a cheap alternative to a client-server approach. This occurs on a huge scale; That measurements have shown 38% of all new torrents Become unavailable Within the first month. [23] A strategy Adopted by Many publishers Which significantly increases availability of unpopular content consists of bundling multiple files in a single swarm. [24] Also More Sophisticated have been Proposed solutions; Generally, cross-tem use qual through multiple torrent torrents Mechanisms Can cooperate to better share content
BitTorrent does not offer anonymity Its users nor security. It is possible to Obtain the IP addresses of all current and previous possibly Participants in a swarm from the tracker. This may expose users with insecure systems to attacks. [22] Also it may expose users to the risk of being Sued, f They are Distributing files without permission from the copyright holder (s). Howevera, there are ways to Promote anonymity; for example, the layers privacy OneSwarm PRESERVING project sharing Mechanisms on top of the original BitTorrent protocol. A moderate degree of anonymity, enough to keep ISPs from giving the user trouble at Leah achieved with seedboxes Can Be Such as Bitport, [26] put.io, [27] or Seedr, [28] Which first download the torrent files to the companies’ servers, Followed by a direct download to the user. [29] [30] Can Be downloaded torrents with a high degree of anonymity by using services Such as i2p. Tor does not Provide anonymity on BitTorrent, [31] and its use is discouraged Also (by blocking this type of Connexions) Reasons for performance. [32] Unlikely Tor, i2p is Designed to work with BitTorrent [33] howevera, with i2p, Can only eu torrents downloaded from within the i2p network. This Can Be useful for users Trying To Avoid Complaints from developer’s copyright ISPs, maintaining privacy, or avoiding Censorship.