P2P redirects on text. For the telecommunications term PTP, look at Point-to-Point.
P2P can also could have for Pay-to-play in gaming.

The peer-to-peer (or even P2P) computer network occurs as network that relies on the computing power and bandwidth of the participants within the network rather than concentrating it in the comparatively couple of servers. P2P networks come occasionally utilized for connecting nodes via largely ad hoc connections. Such networks come utile for several purposes. Sharing content files (watch file sharing) containing audio, video, information or even anything inside digital format is very most common, & realtime information, like telephony traffic, is also passed applying P2P technology.

A term "P2P network" can besides mean grid computing.

a pure peer-to-peer file transport network doesn't use at times the notion of clients or even servers, but only equal peer nodes that simultaneously work when each "clients" & "servers" to the more nodes on the network. This model of network arrangement differs from either a client-server model where communication is commonly to & from either the central server. The average lesson for the not peer-to-peer file transport is an FTP server. a single user uploads a file to the FTP server, so numbers of others download it, by having there is no want for the uploader & downloader to exist as attached at the equivalent instance.

A select few networks & trend lines, like Napster, OpenNAP, or IRC @find, use the client-server structure for a few tasks (e.g., looking) & the peer-to-peer structure for others. Networks like Gnutella or Freenet use a peer-to-peer structure for 100% purposes, & come for instance known as avowedly peer-to-peer networks, although Gnutella is greatly facilitated by directory servers that inform peers of the network addresses of more peers.

Peer-to-peer architecture is one of a key technical indicator conception of the net, described in the number one net Request for Comments, "RFC 1, Host Software" [http://www.ietf.org/rfc/rfc1.txt] dated 7 April 1969. Further recently, a construct has achieved wide prominence among a general public in the context of the absence of central indexing servers in architectures used for exchanging multimedia system files.

Operation of peer-to-peer networks
3 major types of P2P network come:

Pure P2P: Peers work when clients & server There is no central server No central router

Intercrossed P2P: Has the central server that keeps principles in peers & responds to requests for that facts. Peers come responsible hosting a information (when a central server doesn't store files), for allowing the central server underst& what files it obviously part, and for downloading its shareable resources to peers that asking it. Route terminals come utilized addresses, which are then referenced by the placed of indices to obtain an absolute location.

Mixed P2P: Has two pure & intercrossed characteristics

Advantages of peer-to-peer networks
An crucial goal inside peer-to-peer networks is that completely clients provide resources, including bandwidth, storage space, and computing power. So, when nodes arrive & require on a patterns increases, the amount capacity of the technique too increases. This is non admittedly of the client-server architecture by having the fixed placed of servers, where adding supplementary clients may mean slower information transport for 100% users.

the distributed nature & severity of peer-to-peer networks as well increases robustness just inside case of failures by replicating informatiin on top multiple peers, and -- in pure P2P systems -- by enabling peers to call for a information while forgoing relying on a centralised stock server. In the latter instance, no single point of failure in the system.

After a term peer-to-peer was wont to describe a Napster network, it implied that a peer protocol nature was important, however, actually, a neat accomplishment of Napster was a authorisation of the peers (i personally.e., the fringes of the network) around association using a central stock, which manufactured it convenient & effective to talk with available content. the peer protocol was good a most common way to achieve this.

Generational classification of peer-to-peer file sharing networks
A select few humans describe peer-to-peer file-sharing networks by their 'generation'. Therein context, it is on merely to the popular internet-depending file-sharing networks, non sooner search - & business-oriented peer-to-peer systems, which pre-date the children.

First generation
the foremost generation of peer-to-peer file sharing networks experienced a centralised file listing, such as Napster. Courts in the United States ruled that whoever controlled this centralized file listings containing works whose copyright was being infringed was responsible any infringement. In a end, Napster was held liable possibly whenever it used the virtually all advanced technology available to identify works right of first publication holders experienced asked it to prevent, because there are no technology that might identify works by owning 100% certainty is or even potty survive. Napster continues to work in todays world, however the company has taken the fresh counsel, & is currently legally distributing music under a subscription-depending model.

In the focused peer-to-peer model, the user would send the research to the centered server of what it were looking, we.e., song, videos, picture. a server so rem& a names of which peers own a information & facilitates the connection and download.

Second generation
Fallowing Napster found legal troubles, Justin Frankel of Nullsoft set bent produce a network while forgoing the central stock server, & Gnutella was the effect. Alwhen, a Gnutella model of a lot nodes existence compeer quickly died from either either bottlenecks as a network grew from incoming Napster refugees. FastTrack solved a condition by with a bit of nodes become 'further peer than others'.

By electing the few nodes that got extrthe capacity when indexing nodes, & with moo capacity nodes branching slay from either the two, it leave a network that can shell to a very much big size. Gnutella quickly adopted this model, & virtually all todays peer-to-peer networks watch this model, when it allows for big & effective networks while forgoing central servers.

Likewise involved in the 2nd generation come distributed hash tables, which solve the scalability condition by electing various nodes to stock certain hashes (which are then utilized to identify files), allowing convenient & effective shopping for any cases of the file on the network. It is non forswearing their have drawbacks; peradventure virtually all significantly, DHTs don't directly trend lines keyword looking (when opposed to exact-match looking).

Third generation
A third generation of peer-to-peer networks come victims that keep around anonymity features built in. Examples of anon. networks come Freenet, I2P, GNUnet, Entropy.

Friend-to-friend networks only allow already known users (the.k.the. "friends") to attach to the computer, so to each one node can forward requests and files anonymously between its have "friends" nodes; a few one networks come: MUTE / Napshare / ANts P2P / WASTE.

Third generation networks, even so, stand non reached mass usage for file sharing because of the overhead that namelessness features introduce, multiplying the bandwidth mandatory to send a file by having every go-between utilized.

Academic peer-to-peer network
Recently, developers at Pennsylvania State University, in conjunction by having Massachusetts Institute of Technology Open Knowledge Initiative, research worker at Simon Fraser University, and a Internet2 P2P Working Class actiin, keep close at hand been working on an academic application for the peer-to-peer network. This plan known as LionShare is according to another generation network, supplementary specifically a Gnutella model. A independent purpose of this network is to part academic poop between users at several different academic institutions. the LionShare network is according to a crossed model that mixes the Gnutella decentralised peer-to-peer network using a extra traditional client-server network. Users of this program come take a breath to upload files to a server in which it may be shared day and night, irrespective of whether or even does'nt the user is on the internet. This network allows for the tremendously little than normal sharing community.

A independent difference between this network & most more peer-to-peer networks is a fact that the users of LionShare may non exist as anon.. A purpose of this is to deter a sharing of copyrighted lesson across a network, & so refrain from legal issues. An additional difference is the ability to by selection part single files sustaining specific groups. The user is respire to take one by one which users come suspire to receive an single file or even class action of files.

This technology is required in the academic community becautilize of the use of further & big multimedia system files in the schoolroom setting. Further & extra prof come utilizing multimedia system files like audio, streaming videos & powerpoint. Transferring these files to students occurs as hard project that would exist as mass produced tremendously gentler by the network like LionShare.

Legal controversy
Under Usa law, "the Betamax decision" example holds that copying "technologies" are non inherently illegal, in case real non-infringing utilise may be processed of the two. This guide, predating a far flung utilise of the Internet applies to most information networks, including peer-to-peer networks, since distribution of right commissioned files may be performed. These non-infringing utilizes include sending open source software program, public domain files & away from right of first publication works. More jurisdictions tend to look at a situation within somewhat similar ways.

Witharound practice, several, typically virtually all, of the files divided in peer-to-peer networks come copies of copyrighted popular music & motion picture in wide kind of formats (MP3, MPEG, RM, etc.) Sharing one copies is illegal inside virtually all jurisdictions. This has led numbers of observers, including virtually all media corporations & a few peer-to-peer advocates, to conclude that a networks themselves pose grave threats to the constituted distribution model. A the food and drug administration that tries to measure actual pecuniary loss has been somewhat ambiguous. When within paper a being one networks resolutions in massive losses, a actual income doesn't seem to keep around changed great deal since these networks began higher. Whether a threat is really or even non, two a RIAA and the MPAA now spend large numbers of money attempting to lobby lawgiver for the creation of freshly laws, & a select few right of first publication owners pay corporations to help legally challenge users engaging around illegal sharing of their lesson.

Around spite of a Betamax guide, peer-to-peer networks themselves use been targeted per representatives of people originative person & organizations world health organization license their creative works, including industry trade organizations like the RIAA & MPAA as a likely threat. A Napster service was close up by an RIAA suit. In that experience, Napster experienced been deliberately marketed as a way to distribute audio files forswearing permission from either a right of first publication owners.

When actions to defend infringement of copyright by media corporations exp&, a networks develop quickly adapted & constantly turn into each technologically and legally thomas more hard to dismantle. This has caused the users that come actually breaking a law to turn into targets, because when a underlying technology can be legal, the abuse of it by souls redistributing content inside a right of first publication infringing way is clearly non.

Anonymous peer-to-peer networks allow for even even distribution of lesson - legal or does'nt - sustaining little or there are no legal answerability through the wide kind of jurisdictions. Numbers of profess that this may lead to greater or potentially gentler commodities trading of illegal poop & even (when a bit of indicate) help terrorism, and require its regulatiin on victims evidence. Others counter that a possible for illegal utilizes should not halt a technology from either existence utilized for legal purposes, that a presumption of innocence must use, & that non peer-to-peer technologies rather e-mail, which also possess anonymizing services, develop similar capabilities.

Crucial Cases

United states law Sony Corp. v. Universal City Studios (The Betamax decision) MGM v. Grokster

Computer science perspective
Technically, a totally pure peer-to-peer application must implement simply peering protocols that don't recognize the conception of "server" & "client". Such pure peer applications & networks come uncommon. Virtually all networks & applications described when peer-to-peer actually contain or even rely in occasionally non-peer elements, like DNS. Likewise, real globe applications typically utilise multiple protocols & work when client, server, & peer at the same instance, or even above time. Wholly decentralised networks of peers apply been inside use for several years: 2 examples come Usenet (1979) and FidoNet (1984).

Numerous P2P systems utilize stronger peers (extr-peers, very-nodes) when servers & client-peers come attached around the star-such as fashion to one very-peer.

Sun added classes to a Java technology to speed the development of peer-to-peer applications quickly in the late 1990s so that developers could build decentralised rattling period chat applets & applications prior to Instant Messaging networks were popular. This effort is okay, existence continued by having a JXTA project.

Peer-to-peer systems & applications own attracted much of attention from either computer science a food and drug administration; occasionally large scientific research include the Chord project, ARPANET, the PAST storage utility, the P-Grid, a self-organized & emerging overlayer network & a CoopNet content distribution system (see in the image below for external links related to these projects).

Attacks on Peer-to-peer networks
Several peer-to-peer networks come under constant attack by population by using the kind of motives.

Examples include: poisoning attacks (providing files whose contents come different than a description) denial of service attacks (attacks that will produce a network redo super slowly or even break entirely) defection attacks (users or even software program that produce utilise of the network while forgoing contributing resources to that) insertion of viruses to carried information (e.g., downloaded or even even carried files can be infected by by having viruses or more malware) malware in the peer-to-peer network software system itself (e.g., a software package can contain spyware) filtering (network operators might attempt to cease peer-to-peer network information from either existence carried) identity attacks (e.g., run the users of the network & harassing or even legally attacking the two) spamming (e.g., sending unasked data through a network- does'nt necessarily as a denial of service attack)

Virtually all attacks may be defeated or even controlled by careful project of the peer-to-peer network & through the utilize of encoding. P2P network defense is in point of fact closely related to the "Byzantine Generals Problem". But, just about any network might fail whilst a majority of the peers come trying to damage it, & numerous protocols can be rendered impotent far and away fewer totals.

Networks, protocols and applications
Format: network/protocol: listing of applications utilizing that network (operating technique) Everthing networks & protocols come around alphabetical a correct sequence except super similar applications which are then employed around of these entry sustaining a foremost 1 first, determining the place of this super similar applications in the names.

Applejuice network: Applejuice Client Avalanche AudioGnome BitTorrent network: ABC, Azureus, BitAnarch, BitComet, BitSpirit, BitTornado, BitTorrent, BitTorrent++, BitTorrent.Net, G3 Torrent, mlMac, MLdonkey, QTorrent, SimpleBT, Shareaza, TomatoTorrent (Mac OS X) [http://sarwat.net/bittorrent/], TorrentStorm, µTorrent CAKE network: BirthdayCAKE the reference implementation of CAKE Direct Connect network: BCDC++, CZDC++, DC++, NeoModus Direct Connect, JavaDC, DCGUI-QT eDonkey network: aMule (Linux, Mac OS X, others), eDonkey2000, eMule, LMule, MindGem, MLdonkey, mlMac, Shareaza, xMule, iMesh Light, ed2k (eDonkey 2000 protocol) FastTrack protocol: giFT, Grokster, iMesh (and its variants stripped of adware including iMesh Light), Kazaa by Sharman Networks (and its variants stripped of adware including: Kazaa Lite, K++, Diet Kaza and CleanKazaa), KCeasy, Mammoth, MLdonkey, mlMac, Poisoned FotoSwap Freenet network: Entropy (on its own network), Freenet, Frost Gnutella network: Acquisition (Mac OS X), BearShare, BetBug, Cabos, CocoGnut (RISC OS) [http://www.alpha-programming.co.uk/software/cocognut/], Gnucleus Grokster, iMesh, gtk-gnutella (Unix), Kiwi Alpha, LimeWire (Java), MLdonkey, mlMac, Morpheus, Phex Poisoned, Swapper, Shareaza, XoloX Gnutella2 network: Adagio, Caribou, Gnucleus, iMesh, Kiwi Alpha, MLdonkey, mlMac, Morpheus, Shareaza, TrustyFiles HyperCast [http://www.cs.virginia.edu/hypercast] Joltid PeerEnabler: Altnet, Bullguard, Joltid, Kazaa, Kazaa Lite Kad Network (using Kademila protocol): eMule, MindGem, MLdonkey LUSerNet (using LUSerNet protocol): LUSerNet MANOLITO/MP2P network: Blubster, Piolet, RockItNet Napster network: Napigator, OpenNap, WinMX Peercasting type networks: PeerCast, IceShare - P2P implementation of IceCast, [http://www.freecast.org/ Freecast] LiveP2P type networks: CoolStreaming, Cybersky-TV WPNP network: WinMX

more networks: Akamai, Alpine, ANts P2P, Ares Galaxy, Audiogalaxy network, Carracho, Chord, The Circle, Coral [http://www.scs.cs.nyu.edu/coral/], Dexter, Diet-Agents, EarthStation 5 network, Evernet, FileTopia, GNUnet, Grapevine, Groove, Hotwire, iFolder, konspire2b, Madster/Aimster, MUTE, Napshare, OpenFT (Poisoned), P-Grid[http://www.p-grid.org], IRC @find and XDCC, used by IRC clients including: mIRC and Trillian, JXTA, Peersites [http://www.peersites.com], MojoNation, Mnet, Overnet network, Scour, Scribe, Skype, Solipsis a massively multi-participant virtual world, SongSpy network, Soulseek, SPIN, SpinXpress, SquidCam [http://www.squidsoft.com], Swarmcast, WASTE, Warez P2P, Winny, AsagumoWeb, OpenExt, Tesla, soribada, fileswapping, XSC,

An sooner generation of peer-to-peer systems were known as "metacomputing" or even were classed when "middleware". These include: Legion, Globus, Condor, ByteTornado

Multi-network applications
Format: application (networks/protocols) (operating systems) (open source?)

eMule (Edonkey Network, Kad Network) (Microsoft Windows, Linux) (open source) aMule (EDonkey network) (Linux, Mac OS X, FreeBSD, NetBSD, OpenBSD, Windows and Solaris Operating Environment) (open source) Epicea (Epicea, BitTorrent, Edonkey Network, Overnet, FastTrack, Gnutella) (Microsoft Windows) (?) GiFT (own OpenFT protocol, & using plugins - FastTrack, eDonkey and Gnutella) (open source) xfactor (uses GiFT) (Mac OS X) (?) Gnucleus (Gnutella, Gnutella2) (Microsoft Windows) (open source) Hydranode (eDonkey2000) (Microsoft Windows, Linux, Mac OS X) (open source) iMesh (Fasttrack, Edonkey Network, Gnutella, Gnutella2) (Microsoft Windows) (?) Kazaa (FastTrack, Joltid PeerEnabler) (Microsoft Windows) (closed source) Kazaa Lite (FastTrack, Joltid PeerEnabler) (Microsoft Windows) (closed source) KCeasy (Gnutella, Ares, giFT) (?) Kiwi Alpha (Gnutella, Gnutella2) (Microsoft Windows) (?) MindGem (Edonkey Network, Kademlia) (?) MLdonkey (BitTorrent, eDonkey, FastTrack, Gnutella, Gnutella2, Kademlia) (Microsoft Windows, Linux, Mac OS X) (open source) mlMac (BitTorrent, eDonkey, FastTrack, Gnutella, Gnutella2) (?) Morpheus (Gnutella, Gnutella2)(Microsoft Windows) (closed source) Poisoned (FastTrack, Gnutella, Ares, OpenFT, giftd) (Max OS X) (?) Shareaza (BitTorrent, eDonkey, Gnutella, Gnutella2) (Microsoft Windows) (open source) WinMX (Napster, WPNP) (Microsoft Windows) (open source) XNap (OpenNAP, GiFT, Limewire, Overnet, ICQ, IRC) (Java) (open source) Zultrax (Gnutella, ZEPP) (?)