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.

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

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.

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

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.

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

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

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.

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

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

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

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

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.

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.

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.

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.

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.

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.

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.

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

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.

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

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

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.