IRC
Internet Relay Chat (IRC) is a text-based chat system for instant messaging. IRC is designed for group communication in discussion forums, called channels,[1] but also allows one-on-one communication via private messages[2] as well as chat and data transfer,[3] including file sharing.[4]
For other uses, see IRC (disambiguation).Abbreviation
IRC
August 1988
Not yet superseded
IRCv3 (standards process working group)
Application layer
6667, 6697
Internet Relay Chat is implemented as an application layer protocol to facilitate communication in the form of text. The chat process works on a client–server networking model. Users connect, using a client—which may be a web app, a standalone desktop program, or embedded into part of a larger program—to an IRC server, which may be part of a larger IRC network. Examples of programs used to connect include Mibbit, IRCCloud, KiwiIRC, and mIRC.
IRC usage has been declining steadily since 2003, losing 60 percent of its users.[5] In April 2011, the top 100 IRC networks served more than 200,000 users at a time.[6]
Search engines[edit]
There are numerous search engines available to aid the user in finding what they are looking for on IRC.[101][102] Generally the search engine consists of two parts, a "back-end" (or "spider/crawler") and a front-end "search engine".
The back-end (spider/webcrawler) is the work horse of the search engine. It is responsible for crawling IRC servers to index the information being sent across them. The information that is indexed usually consists solely of channel text (text that is publicly displayed in public channels). The storage method is usually some sort of relational database, like MySQL or Oracle.
The front-end "search engine" is the user interface to the database. It supplies users with a way to search the database of indexed information to retrieve the data they are looking for. These front-end search engines can also be coded in numerous programming languages.
Most search engines have their own spider that is a single application responsible for crawling IRC and indexing data itself; however, others are "user based" indexers. The latter rely on users to install their "add-on" to their IRC client; the add-on is what sends the database the channel information of whatever channels the user happens to be on.
Many users have implemented their own ad hoc search engines using the logging features built into many IRC clients. These search engines are usually implemented as bots and dedicated to a particular channel or group of associated channels.
IRC still lacks a single globally accepted standard convention for how to transmit characters outside the 7-bit ASCII repertoire.
IRC servers normally transfer messages from a client to another client just as byte sequences, without any interpretation or recoding of characters. The IRC protocol (unlike e.g. MIME or HTTP) lacks mechanisms for announcing and negotiating character encoding options. This has put the responsibility for choosing the appropriate character codec on the client. In practice, IRC channels have largely used the same character encodings that were also used by operating systems (in particular Unix derivatives) in the respective language communities:
Today, the UTF-8 encoding of Unicode/ISO 10646 would be the most likely contender for a single future standard character encoding for all IRC communication, if such standard ever relaxed the 510-byte message size restriction. UTF-8 is ASCII compatible and covers the superset of all other commonly used coded character set standards.
File sharing[edit]
Much like conventional P2P file sharing, users can create file servers that allow them to share files with each other by using customised IRC bots or scripts for their IRC client. Often users will group together to distribute warez via a network of IRC bots.[103]
Technically, IRC provides no file transfer mechanisms itself; file sharing is implemented by IRC clients, typically using the Direct Client-to-Client (DCC) protocol, in which file transfers are negotiated through the exchange of private messages between clients. The vast majority of IRC clients feature support for DCC file transfers, hence the view that file sharing is an integral feature of IRC.[104] The commonplace usage of this protocol, however, sometimes also causes DCC spam. DCC commands have also been used to exploit vulnerable clients into performing an action such as disconnecting from the server or exiting the client.