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

The fourth P2P-Generation

Streams over P2P

Apart from the traditional file sharing there are services that send streams instead of files over a P2P network. Thus one can hear radio and watch television without any server involved -- the streaming media is distributed over a P2P network. It is important that instead of a treelike network structure, a swarming technology known from BitTorrent is used. Best examples are Peercast, Miro, Cybersky and demo TV.

General

* Broadcatching
* Podcast

Tree structure

* CoolStreaming
* Peercast

Swarm structure such as BitTorrent

* Djingle
* Icecast
* Joost
* MediaBlog
* PeerCast
* PPLive
* PPStream
* SopCast
* TVUPlayer
* Vuze

Third P2P-Generation

indirect and encrypted

The third generation of peer-to-peer networks are those that have anonymity features built in. Examples of anonymous networks are ANts P2P, RShare, Freenet, I2P, GNUnet and Entropy.

A degree of anonymity is realized by routing traffic through other users' clients, which have the function of network nodes. This makes it harder for someone to identify who is downloading or who is offering files. Most of these programs also have strong encryption to resist traffic sniffing.

Friend-to-friend networks only allow already-known users (also known as "friends") to connect to the user's computer, then each node can forward requests and files anonymously between its own "friends'" nodes.

Third-generation networks have not reached mass usage for file sharing because most current implementations incur too much overhead in their anonymity features, making them slow or hard to use. However, in countries where very fast fiber-to-the-home Internet access is commonplace, such as Japan, a number of anonymous file-sharing clients have already reached high popularity.

An example might be: Petra gives a file to Oliver, then Oliver gives the file to Anna. Petra and Anna thus never become acquainted and thus are protected. Often used virtual IP addresses obfuscate the user's network location because Petra only knows the virtual IP of Anna. Although real IP's are always necessary to establish a connection between Petra and Oliver, nobody knows if Anna really requested and Petra really send the file or if they just forward it (As long as they won't tell anyone their virtual IP's!). Additionally all transfers are encrypted, so that even the network administrators cannot see what was sent to whom. Example software includes WASTE, JetiANts, Tor and I2P. These clients differ greatly in their goals and implementation. WASTE is designed only for small groups and may therefore be considered Darknet; ANts and I2P are public Peer-to-Peer systems, with anonymization provided exclusively by routing reach.

Ants network

* ANts P2P
* JetiANts
* Hornet

Mute network

* MUTE
* Kommute - KDE

I2P network

* I2P
* I2Phex - Gnutella over I2P
* iMule - eDonkey (Kademlia) over I2P
* Azureus - has I2P plugin

Retroshare-Network (F2F Instant Messenger)

* Retroshare Instant Messenger - Retroshare Chat Messenger for privacy of filesharing

other networks or clients

* Alliance
* Freenet
* GNUnet
* Nodezilla
* OFF System
* Perfect Dark
* Proxyshare
* RShare
* Share
* Tor
* WinNY
* Zultrax

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.