The World of Peer-to-Peer (P2P)/Networks and Protocols/IRC

Internet Relay Chat (IRC)
Internet Relay Chat, commonly abbreviated IRC is a real-time text-based multi-user communication protocol specification and implementation; it relays messages between users on the network. IRC was born sometime in 1988, from the mind of Jarkko Oikarinen. According to IRChelp.org ( http://www.irchelp.org/irchelp/rfc/ ), the official specification for IRC was written in 1993 in the RFC format. The protocol was defined in the "RFC 1459: Internet Relay Chat Protocol", a really excellent source for both an introduction to and detailed information about the IRC protocol.

IRC's largest unit of architecture is the IRC network. There are perhaps hundreds of IRC networks in the world each one running parallel and disjoint from the others. A client logged into one network can communicate only with other clients on the same network, not with clients on other networks. Each network is composed of one or more IRC servers. An IRC client is a program that connects to a given IRC server in order to have the server relay communications to and from other clients on the same network but not necessarily the same server.

Messages on IRC are sent as blocks. That is, other IRC clients will not see one typing and editing as one does so. One creates a message block (often just a sentence) and transmits that block all at once, which is received by the server and based on the addressing, delivers it to the appropriate client or relays it to other servers so that it may be delivered or relayed again, et cetera. For a look into the messages exchanged on an IRC network you can take a look into (http://www.alien.net.au/irc/irc2numerics.html), it clearly identifies the several implementations and functions.

Once connected to a server, addressing of other clients is achieved through IRC nicknames. A nickname is simply a unique string of ASCII characters identifying a particular client. Although implementations vary, restrictions on nicknames usually dictate that they be composed only of characters a-z, A-Z, 0-9, underscore, and dash.

Another form of addressing on IRC, and arguably one of its defining features, is the IRC channel. IRC channels are often compared to CB Radio (Citizen's Band Radio) channels. While with CB one is said to be "listening" to a channel, in IRC one's client is said to be "joined" to the channel. Any communication sent to that channel is then "heard" or seen by the client. On the other hand, other clients on the same network or even on the same server, but not on the same channel will not see any messages sent to that channel.

Updated information on IRC can be obtained at IRC.org, the move to support IPv6 and the new technical papers, the IETF (Internet Engineering Task-Force) approved the most current technical drafts ( April 2000 - authored by C Kalt): RFC 2810 : IRC Architecture RFC 2811 : IRC Channel-Management RFC 2812 : IRC Client-Protocol RFC 2813 : IRC Server-Protocol These documents are already available on IRC.org's official FTP-server, reachable at ftp://ftp.irc.org/irc/server While IRC is by definition not a P2P protocol, IRC does have some extensions that support text and file transmission directly from client to client without any relay at all. These extensions are known as DCC (Direct Client to Client) and CTCP (Client To Client Protocol).

Ident Protocol
The Ident Protocol, specified in RFC 1413, is an Internet protocol that helps identify the user of a particular TCP connection, and differentiate them from others sharing the same connection on the a server.

The Ident Protocol is designed to work it self as a server daemon, on a user's computer, where it receives requests to a specified port, generally 113. The server will then send a specially designed response that identifies the username of the current user.

Most standalone Windows machines do not have an Ident service running or present by default, in this case you may need to run your own Ident server (there are several stand alone servers available), on the other hand if you are on a Unix/Linux machine the service is there by default. Some Windows IRC clients have also an Ident server built into them.

The reason for having an running Ident server is due to IRC servers using the information for security reasons (not a particularly efficient way of doing), some going so far as blocking clients without an Ident response, the main reason being that it makes it much harder to connect via an "open proxy" or a system where you have compromised a single account of some form but do not have root.

CTCP (Client To Client Protocol) Protocol
With CTCP, clients can implement commands such as "ctcp nickname version" or "ctcp nickname ping" to get some interesting infos about other users (like mIRC does).

Bots or Robots
IRC systems also support (ro)bots, in this case they are not real users but a collection of commands that are loaded from a script (text) file into the IRC client, or even a stand alone program that connects to a IRC channel. They serve to ease the human interaction with the system, provide some kind of automation or even to test or implement some AI.

Basic Commands
Here are some basic commands for IRC:

Privileged User Commands
Commands for half-operators, channel operators, channel owners, and Admins:

IRC Networks

 * EFnet
 * Undernet
 * Dalnet
 * Rede Portuguesa de IRC (PTnet) ( http://www.ptnet.org/ ), is the biggest Portuguese IRC network, it was created in 1997, you can get an updated list of it's server ( http://www.ptnet.org/servidores ).

Software Implementations

 * KVIrc ( http://www.kvirc.net/ ) an open source (GPL) portable IRC client based on the Qt GUI toolkit and coded in C++.
 * Bersirc ( http://bersirc.free2code.net/index.php/home/ ), an open source IRC client (LGPL), coded in C, that runs on Windows (Linux and Mac OS X ports under development) by utilizing the Claro GUI Toolkit.
 * XChat ( http://www.xchat.org/ ) is an IRC (chat) program for Windows and UNIX (Linux/BSD) operating systems. I.R.C. is Internet Relay Chat. XChat runs on most BSD and POSIX compliant operating systems. Open Source (GPL), coded in C.
 * Irssi ( http://irssi.org/ ), an IRC client program originally written by Timo Sirainen, and released under the terms of the GNU General Public License. It is written in the C programming language and in normal operation uses a text-mode user interface.
 * mIRC ( http://www.mirc.co.uk/ ), a shareware Internet Relay Chat client for Windows, created in 1995 and developed by Khaled Mardam-Bey. This was originally its only use, but it has evolved into a highly configurable tool that can be used for many purposes due to its integrated scripting language.

You can also check Wikipedia list of IRC clients and Comparison of Internet Relay Chat clients (not up-to-date)...

Invisible IRC Project
A technological advancement in relation to normal IRC networks, created by invisibleNET, a research & development driven organization whose main focus is the innovation of intelligent network technology. Its goal is to provide the highest standards in security and privacy on the widely used, yet notoriously insecure Internet.

Invisible IRC Project (http://invisibleip.sourceforge.net/iip/) is a three-tier, peer distributed network designed to be a secure and private transport medium for high speed, low volume, dynamic content. Features:


 * Perfect Forward Security using Diffie-Hellman Key Exchange Protocol
 * Constant session key rotation
 * 128 bit Blowfish node-to-node encryption
 * 160 bit Blowfish end-to-end encryption
 * Chaffed traffic to thwart traffic analysis
 * Secure dynamic routing using cryptographically signed namespaces for node identification
 * Node level flood control
 * Seamless use of standard IRC clients
 * Gui interface
 * Peer distributed topology for protecting the identity of users
 * Completely modular in design, all protocols are plug-in capable

The IIP software is released under the GPL license and is available for Windows 98/ME/NT/2000/XP, *nix/BSD and Mac OSX, coded in C.