File-sharing program

A file-sharing program is used to directly or indirectly transfer files from one computer to another computer over a network (e.g. the Internet). While the term may be used to describe client-server disk sharing (also known as shared file access or disk mounting), it is more commonly used to describe file sharing using the peer-to-peer (P2P) model.

Peer-to-peer file sharing typically operates using a network, such as Gnutella or BitTorrent. There are trade offs to using one network over another network. A variety of file-sharing programs are available on these different networks. It is common for commercial file sharing clients to contain abrasive advertising software or spyware.

Categories of clients

* Centralized Clients: OpenNap
o Benefits: Faster searching and downloading
o Negatives: Often more vulnerable to legal and DDOS attacks

* Decentralized clients: Gnutella
o Benefits: Usually more reliable and rarely shut down
o Negatives: Generally slower than centralized systems

* Decentralized tracker-based clients: BitTorrent
o Benefits: Very fast due to concentration of bittorrent networks on a single file, is principally used to offer new, large files for download, many tracker sites available
o Negatives: Not centrally searchable, tracker sites are often closed down from legal suits or fail, not truly anonymous

* Multi-network clients
o Benefits: allows connection to more than one network, almost always on the client side.
o Negatives: often playing catch-up to individual networks' changes and updates.

* Anonymous peer-to-peer: Freenet, GNUnet, MUTE, I2P
o Benefits: allows for the uncensored free flow of information and ideas
o Negatives: due to anonymity it allows for questionable or illegal material to be exchanged easier than other networks, often slower than regular p2p because of the overhead

* Private file-sharing networks

Economic impact

As files sharing has spread a debate on how the infringement of copyright (in terms of file sharing copyrighted audio and visual content) impacts on legal distribution of especially music. In a broader context commentators have pointed out that the music industry, along with other types of media such as film and TV are having a difficult time adapting to the digital age.

Software Industry

According to Moisés Naím, even in countries and regions with high intellectual property enforcement standards, such as the US or the EU, piracy rates of one-quarter or more for popular software and operating systems are common. The pirated software is distributed through file sharing at unprecedented rates, and according to Naím, software manufacturers dread the "one disc" effect: a phenomenon in which a single counterfeited copy can be propagated until it has taken over an entire country, pushing the legitimate product out of the market.

Copyright issues

File sharing has grown in popularity with the proliferation of high-speed Internet connections, and the relatively small file size and high-quality MP3 audio format. File sharing is a legal technology with legal uses, however many users use it to give and accept copyrighted materials without permission or authorization, and this is viewed by some as piracy of intellectual property, also known as copyright infringement.

Despite the existence of various international treaties, there are still sufficient variations between countries to cause significant difficulties in the protection of copyright. Recent years have seen copyright owners challenging file sharing networks, leading to litigation by industry bodies against private individual file sharers. The legal issues surrounding file sharing have been the subject of debate and conferences, especially among lawyers in the entertainment industries.

The challenges facing copyright holders in the face of file sharing systems highlight that current copyright law and enforcement may not be sufficient in dealing with rapidly developing new technologies and uses. Other challenges include ambiguities in the interpretation of copyright law and varying copyright legislations. The high number of individuals engaged in file sharing of copyrighted material means that copyright holders face problems relating to mass litigation and the development of processes for evidence and discovery.

File sharing technology has evolved in response to legal challenges. There is a low technical barriers to entry for would-be sharers, and many file sharing approaches now obfuscate or hide the fact that sharing is happening, or the identities of those involved. For example: encryption and darknets. Furthermore it is contested whether the transfer of segmented files constitutes copyright infringement in itself based on existing laws.

Further challenges have arisen because of the need to balance self-protection against fair use. A perceived overbalance towards protection (in the form of media that cannot be backed up, cannot be played on multiple systems by the owner, or contains rootkits or irksome security systems inserted by manufacturers), has led to a backlash against protection systems in some quarters. For example, the first crack of AACS was inspired by a perceived unfair restriction on owner usage.

Second P2P-Generation

Decentralization

After Napster encountered legal troubles, Justin Frankel of Nullsoft set out to create a network without a central index server, and Gnutella was the result. Unfortunately, the Gnutella model of all nodes being equal quickly died from bottlenecks as the network grew from incoming Napster refugees. FastTrack solved this problem by having some nodes be 'more equal than others'.

By electing some higher-capacity nodes to be indexing nodes, with lower capacity nodes branching off from them, FastTrack allowed for a network that could scale to a much larger size. Gnutella quickly adopted this model, and most current peer-to-peer networks implement this design, as it allows for large and efficient networks without central servers.

Also included in the second generation are distributed hash tables (DHTs), which help solve the scalability problem by electing various nodes to index certain hashes (which are used to identify files), allowing for fast and efficient searching for any instances of a file on the network. This is not without drawbacks; perhaps most significantly, DHTs do not directly support keyword searching (as opposed to exact-match searching).

The best examples are Gnutella, Kazaa or eMule with Kademlia, whereby Kazaa has still a central server for logging in. eDonkey2000/Overnet, Gnutella, FastTrack and Ares Galaxy have summed up approx. 10.3 million users (as of April 2006, according to slyck.com). This number does not necessarily correspond to the actual number of persons who use these networks; it must be assumed that some use multiple clients for different networks.

Multi-Network-Clients

Further networks or clients

Web-based sharing

Webhosting is also used for file-sharing, since it makes it possible to exchange privately. In small communities popular files can be distributed very quickly and efficiently. Web hosters are independent of each other; therefore contents are not distributed further. Other terms for this are one-click hosting and web-based sharing.

File Sharing On The Social Graph

Recently, Facebook opened up its API to 3rd party developers that has allowed for a new type of file-sharing service to emerge. Box.net and FreeDrive.com are two examples of companies that have specific Facebook Applications that allow file sharing to be easily accomplished between friends.

Server-client-protocols

* Audiogalaxy - Service ended in the middle of 2002.
* Direct Connect
* Napster - Closed in its original form in July 2001, since changed to a fee-based service.
* Scour Exchange - The second exchange network after Napster. No longer exists.
* Soulseek - Still popular today despite being relatively old, with more than 120,000 users online at any time.
* TinyP2P - 15 lines Python - SOURCE code
* WinMX - The original Frontcode servers were switched off in September 2005, but alternate servers can be used by installing a Software Patch.

File sharing

File sharing refers to the providing and receiving of digital files over a network, usually following the peer-to-peer (P2P) model, where the files are stored on and served by personal computers of the users. Most people who engage in file sharing on the Internet both provide (upload) files and receive files

P2P file sharing is distinct from file trading in that downloading files from a P2P network does not require uploading, although some networks either provide incentives for uploading such as credits or forcing the sharing of files being currently downloaded.

USENET was the first global file sharing network. Files are posted to alt.binary.* groups by users and copies are propagated to all hosts that carry that particular group. Unlike the later peer-to-peer file sharing networks, requests for a file relies on people asking others to post them, and users save them if they want those files.

First P2P-generation: Server-client

The first generation of peer-to-peer file sharing networks had a centralized server system. This system controls traffic amongst the users. The servers store directories of the shared files of the users and are updated when a user logs on. In the centralized peer-to-peer model, a user would send a search to the centralized server of what they were looking for. The server then sends back a list of peers that have the data and facilitates the connection and download. The Server-Client system is quick and efficient because the central directory is constantly being updated and all users had to be registered to use the program. However, there is only a single point of entry, which could result in a collapse of the network. In addition, it is possible to have out of date information or broken links if the server is not refreshed.

The first file-sharing programs marked themselves by inquiries to a server, either the data to the download held ready or in appropriate different Peers and so-called Nodes further-obtained, so that one could download there. Two examples were Napster (today using a pay system) and eDonkey2000 in the server version (today, likewise with Overnet and KAD - network decentralized). Another notable instance of peer to peer file sharing, which still has a free version, is Limewire.