I2P

File:I2P 0.9.8.1.png I2P 0.9.8.1 Router Console
Original author(s)	I2P Team
Initial release	2003
Stable release	0.9.15 / September 20, 2014 (2014-09-20) 0.9.15 Release
Repository	github.com/i2p/i2p.i2p
Written in	Java; C
Operating system	Cross-platform
Available in	English, Spanish Incomplete translations: Russian, French,Romanian, German, Swedish, Italian, Portuguese, Chinese, Dutch, Polish, Hungarian, Arabic, Japanese, Estonian
Type	Overlay network
License	Free/Open Source – Multiple licenses Public domain, BSD, GPL, MIT, Artistic License
Website	geti2p.net

The Invisible Internet Project (I2P) 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.

Technical design

I2P is beta software since 2003. 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, email, 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, killyourtv and Complication have continued to lead development efforts, and are assisted by numerous contributors.

Software

I2P router console

iMule

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.

General networking

• 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 programming language to communicate over I2P, by using a socket-based interface to the I2P router.
• BOB (Basic Open Bridge) is a less complex app to router protocol similar to "SAM"
• Orchid outproxy Tor plugin

Chat

• Any IRC client made for the Internet Relay Chat can work, once connected to the I2P IRC server (to the localhost).

File sharing

• 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 MS 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.
• I2Phex is a port of the popular Gnutella client Phex to I2P. It is stable and fairly functional.

Email

• Bitmessage.ch can be used over I2P or Tor.
• I2P has a free pseudonymous e-mail service run by an individual called Postman. Susimail is a web-based email 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 user@mail.i2p and public internet email users from a user@i2pmail.org address.
• I2P-Bote is an I2P plugin, fully decentralized and distributed email system. It supports different identities and does not expose email headers. Currently (2014), it is still in beta version and can only be accessed via its web application 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 email server that could link different email 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 address 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. No accounts need to be registered, all you have to do in order to use it is install and connect it, and create a new identity. I2P-Bote can be installed as a router plugin (i2p-link).

Instant messaging

• 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. In addition to messaging, file transfer is also supported.

Publishing

• 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.

Routers

• I2PBerry is a Linux distribution which can be used as a router to encrypt and route network traffic through the I2P network.

Android

• Early builds of a I2P Router application for Android can be found at the development forums inside the I2P network.
• Nightweb is an Android application that utilizes I2P and Bittorrent to share blog posts, photos, and other similar content. It can also be run as a desktop application. It is no longer in development.

Terminology

Eepsite

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.

.i2p

'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.

EepProxy

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.

Peers, I2P nodes

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. You may read : node (networking).

Tunnels

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).

See also

• Anonymous P2P
• Rendezvous protocol
• Crypto-anarchism
• Garlic routing
• Secure communication
• Threat model

Software :

• Retroshare
• Tor (anonymity network)
• Tor2web

External links

• Official website
• Official website : tutorials (in the area papers)
• I2P Android package at the F-Droid repository
• Video tutorial : installing I2P on a Debian Linux system (2010) (copy), by the net activists group Telecomix.
• Video tutorial. "Cyber Ninja" : I2P setup on Windows (2013. #PM2020)
• I2P - Community Ubuntu Documentation (2011)
• Linux Today - I2P - Anonymity for the Masses (2011)