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|Stable release||0.9.6 / May 28, 2013|
|License||Free/Open Source - Multiple licenses Public domain, BSD, GPL, MIT, Artistic License|
I2P (Invisible Internet Project) is a computer network layer that allows applications to send messages to each other pseudonymously and securely. Uses include anonymous web surfing, chatting, blogging and file transfers. The software that implements this layer is called an I2P router and a computer running I2P is called an I2P node. The software is free and open source and is published under multiple licenses. The name I2P is derived from Invisible Internet Project, which, in pseudo-mathematical notation, is represented as I²P.
I2P is beta software. Developers emphasize that there are likely to be bugs in the software and that there has been insufficient peer review to date. However, they believe the code is now reasonably stable and well-developed, and more exposure can help development of I2P.
The network itself is strictly message-based (like IP), but there is a library available to allow reliable streaming communication on top of it (similar to TCP, although from version 0.6 there is a new UDP-based SSU transport). All communication is end-to-end encrypted (in total there are four layers of encryption used when sending a message), and even the end points ("destinations") are cryptographic identifiers (essentially a pair of public keys), so that neither sender nor recipient of a message need to reveal their IP address to the other side or to third-party observers.
Although many of the developers had been a part of the Invisible IRC Project (IIP) and Freenet communities, there are significant differences between their designs and concepts. IIP was an anonymous centralized IRC server. Freenet is a censorship-resistant distributed data store. I2P is an anonymous peer-to-peer distributed communication layer designed to run any traditional internet service (e.g. Usenet, E-mail, IRC, file sharing, Web hosting and HTTP, Telnet), as well as more traditional distributed applications (e.g. a distributed data store, a web proxy network using Squid, or DNS).
Many developers of I2P are known only under pseudonyms. While the previous main developer, jrandom, is currently on hiatus, others, such as zzz and Complication have continued to lead development efforts, and are assisted by numerous contributors.
Since I2P is an anonymous network layer, it is designed so other software can use it for anonymous communication. As such there are a variety of tools currently available for I2P or in development.
The I2P router is controlled through the router console which is a web frontend accessed through a web browser.
- I2PTunnel is an application embedded into I2P that allows arbitrary TCP/IP applications to communicate over I2P by setting up "tunnels" which can be accessed by connecting to pre-determined ports on localhost.
- SAM (Simple Anonymous Messaging) is a protocol which allows a client application written in any language to communicate over I2P, by using a socket-based interface to the I2P router.
- Several programs provide BitTorrent functionality for use within the I2P network. Each relies on the user being able to access the I2P network with a web browser to download the .torrent files. Users cannot connect to non-I2P torrents or peers from within I2P, nor can they connect to I2P torrents or peers from outside I2P. I2PSnark, included in the I2P install package, is a port of the BitTorrent client named Snark. Vuze, formerly known as Azureus, is a BitTorrent client that includes a plugin for I2P, allowing anonymous swarming through this network. This plugin is still in an early stage of development, however it is already fairly stable. I2P-BT is a BitTorrent client for I2P that allows anonymous swarming for file sharing. This client is a modified version of the original BitTorrent 3.4.2 program which runs on Windows and most dialects of Unix in a GUI and command-line environment. It was developed by the individual known as 'duck' on I2P in cooperation with 'smeghead'. It is no longer being actively developed; however, there is a small effort to upgrade the I2P-BT client up to par with the BitTorrent 4.0 release. I2PRufus is an I2P port of the Rufus BitTorrent client. Robert (P2P Software) is the most actively maintained I2PRufus fork. And there is "I2P-Transmission".
- iMule (invisible Mule)  is a port of eMule for I2P network. iMule is made for anonymous file sharing. In contrast to other eDonkey clients, iMule only uses the Kademlia for proceeding to connect through I2P network, so no servers are needed.
- I2P has a free pseudonymous e-mail service run by an individual called Postman. Susimail is a web-based e-mail client intended primarily for use with Postman's mail servers, and is designed with security and anonymity in mind. Susimail was created to address privacy concerns in using these servers directly using traditional email clients, such as leaking the user's hostname while communicating with the SMTP server. It is currently included in the default I2P distribution, and can be accessed through the I2P router console web interface. Mail.i2p can contact both i2p email users, via firstname.lastname@example.org and public internet email users from a email@example.com address.
- I2P-Bote is an I2P-internal, fully decentralized and distributed e-mail system. It supports different identities and does not expose e-mail headers. Currently, it is still alpha software and can only be accessed via its web interface, but POP support is planned. All bote-mails are transparently end-to-end encrypted and, optionally, signed by the sender's private key, thus removing the need for PGP or other privacy software. I2P-Bote offers additional anonymity by allowing for the use of mail relays with variable length delays. As it is decentralized, there is no e-mail server that could link different e-mail identities as communicating with each other (profiling): Even the nodes relaying the mails do not know the sender, and apart from sender and receiver, only the end of the high-latency mail route and the storing nodes will know to whom (which I2P node - the user's ip is still hidden by I2P) the mail is destined. The original sender can have gone offline long before the mail becomes available on the other side.
- I2P-Messenger is a simple Qt-based, serverless, end-to-end-encrypted instant messenger for I2P. No servers can log the user's conversations, no ISP can log with whom the user chats, when, or for how long. As it is serverless, it can make use of I2P's end-to-end encryption, preventing any node between two parties from having access to the plain text. I2P-Messenger can be used for fully anonymous instant communication with persons the user doesn't even know, or, alternatively, to communicate securely and untraceably with friends, family members, or colleagues. Thus, it is also a useful tool against data retention in a surveillance society. In addition to messaging, file transfer is also supported.
- Syndie is a content distributing application which support blogs, newsgroups, forums for I2P, which is also usable through the Tor network and the normal unencrypted web; it is currently at alpha release.
There is a port of i2p to android, available at sponge.i2p.to.
- Eepsites are websites that are hosted anonymously within the I2P network. Eepsite names end in .i2p, such as ugha.i2p or forum.i2p. EepProxy can locate these sites through the cryptographic identifier keys stored in the hosts.txt file found within the I2P program directory. Typically, I2P is required to access these eepsites.
- The EepProxy program handles all communication between the browser and any eepsite. It functions as a proxy server that can be used by any web browser.
.i2p is a pseudo-top-level domain which is only valid within the I2P overlay network scope. .i2p names are resolved by browsers by submitting requests to EepProxy which will resolve names to an I2P peer key and will handle data transfers over the I2P network while remaining transparent to the browser.
- Other machines using I2P that are connected to user's machine within the network. Each machine within the network shares the routing and forwarding of encrypted packets.
- Every ten minutes, a connection is established between the user's machine and another peer. Data to and from the user, along with the data for other peers (routed through the user's machine), pass through these tunnels and are forwarded to their final destination (may include more jumps).
- "Status Update 01 2008". i2p2.de.
- SAM - I2P. i2p2.de.
- BOB - I2P. i2p2.de.
- BOB: Basic Open Bridge API to the I2P router. BOB official eepsite
- I2P Bittorrent FAQ. i2p2.de forum.
- The Hunting of the Snark Project - BitTorrent Application Suite. klomp.org.
- Azureus: Plugin Details for I2P Network Plugin. azureus.sourceforge.net.
- I2P Howto (setup tutorial). azureus.sourceforge.net.
- Rufus - BitTorrent Client : Home. rufus.sourceforge.net.
- iMule download. aceini.no-ip.info[dubious ]