26 Facts About IRC


IRC is designed for group communication in discussion forums, called channels, but allows one-on-one communication via private messages as well as chat and data transfer, including file sharing.

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IRC usage has been declining steadily since 2003, losing 60 percent of its users.

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IRC was created by Jarkko Oikarinen in August 1988 to replace a program called MUT on a BBS called OuluBox at the University of Oulu in Finland, where he was working at the Department of Information Processing Science.

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The first IRC network was running on a single server named tolsun.

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IRC then grew larger and got used on the entire Finnish national network—FUNET—and then connected to Nordunet, the Scandinavian branch of the Internet.

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In November 1988, IRC had spread across the Internet and in the middle of 1989, there were some 40 servers worldwide.

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Around that time IRC was used to report on the 1991 Soviet coup d'etat attempt throughout a media blackout.

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Largest IRC networks have traditionally been grouped as the "Big Four"—a designation for networks that top the statistics.

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The Big Four networks change periodically, but due to the community nature of IRC there are a large number of other networks for users to choose from.

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IRC reached 6 million simultaneous users in 2001 and 10 million users in 2003, dropping to 371k in 2018.

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Top 100 IRC networks have around 228k users connected at peak hours.

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IRC is an open protocol that uses TCP and, optionally, TLS.

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Standard structure of a network of IRC servers is a tree.

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In early implementations of IRC this had to be hard-coded in the client but there is a de facto standard extension to the protocol called ISUPPORT that sends this information to the client at connect time using numeric 005.

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RFC 1459 claims that IRC operators are "a necessary evil" to keep a clean state of the network, and as such they need to be able to disconnect and reconnect servers.

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Additionally, to prevent malicious users or even harmful automated programs from entering IRC, IRC operators are usually allowed to disconnect clients and completely ban IP addresses or complete subnets.

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Issues in the original design of IRC were the amount of shared state data being a limitation on its scalability, the absence of unique user identifications leading to the nickname collision problem, lack of protection from netsplits by means of cyclic routing, the trade-off in scalability for the sake of real-time user presence information, protocol weaknesses providing a platform for abuse, no transparent and optimizable message passing, and no encryption.

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IRC served as an early laboratory for many kinds of Internet attacks, such as using fake ICMP unreachable messages to break TCP-based IRC connections to annoy users or facilitate takeovers.

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Apart from causing problems within IRC, this encouraged people to conduct denial-of-service attacks against IRC servers in order to cause netsplits, which they would then abuse.

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Typical use of bots in IRC is to provide IRC services or specific functionality within a channel such as to host a chat-based game or provide notifications of external events.

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However, some IRC bots are used to launch malicious attacks such as denial of service, spamming, or exploitation.

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The purpose is to maintain a connection to an IRC server, acting as a relay between the server and client, or simply to act as a proxy.

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IRC still lacks a single globally accepted standard convention for how to transmit characters outside the 7-bit ASCII repertoire.

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In practice, IRC channels have largely used the same character encodings that were used by operating systems in the respective language communities:.

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Technically, IRC provides no file transfer mechanisms itself; file sharing is implemented by IRC clients, typically using the Direct Client-to-Client protocol, in which file transfers are negotiated through the exchange of private messages between clients.

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The vast majority of IRC clients feature support for DCC file transfers, hence the view that file sharing is an integral feature of IRC.

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