Editing IRC (section)

===Hostmasks===
A hostmask is a unique identifier of an IRC [[client (computing)|client]] connected to an IRC [[Server (computing)|server]].<ref name="thiedeke-2003">{{cite book
| editor-last1        = Thiedeke
| editor-first1       = Udo
| last1               = Döring
| first1              = Nicola 
| last2               = Schestag
| first2              = Alexander 
| title       = Virtuelle Gruppen: Charakteristika und Problemdimensionen
| chapter-url         = https://books.google.com/books?id=aQ74THYRyYsC&q=hostmask&pg=PA315
| access-date  = 30 March 2010
| edition     = 2nd
| date        = 23 September 2003
| publisher   = {{Interlanguage link|Springer VS|de}}
| language    = de
| isbn        = 978-3-531-33372-4
| pages       = 314, 337
| chapter     = Soziele Norman in virtuellen Gruppen: ein empirische Analyse am Beispiel ausghewähiter Chat-Channels
}}</ref><ref name="rogers-2005">{{cite book
| last        = Rogers
| first       = Russ
| editor-last = Devost
| editor-first = Matthew G.
| title       = Hacking a Terror Network: The Silent Threat of Covert Channels
| chapter-url         = https://books.google.com/books?id=e3ggsGgTzUgC&q=Hostmask+IRC&pg=PA10
| access-date  = 30 March 2010
| edition     = 1st
| date        = 1 December 2004
| publisher   = Syngress Publishing
| location    = [[Rockland, Massachusetts]]
| isbn        = 978-1-928994-98-5
| page        = 10
| chapter     = The Mind of Terror
}}</ref> IRC [[IRCd|servers]], [[Internet Relay Chat services|services]], and other clients, including [[Internet Relay Chat bot|bots]], can use it to identify a specific IRC session.

The format of a hostmask is <code>nick!user@host</code>. The hostmask looks similar to, but should not be confused with an [[e-mail address]].

The nick part is the nickname chosen by the user and may be changed while connected.
The user part is the username reported by [[ident protocol|ident]] on the client.<ref name="petersen-2002">{{cite book
| editor-last = Petersen
| editor-first = Julie K.
| title       = The Telecommunications Illustrated Dictionary
| chapter-url         = https://books.google.com/books?id=b2mMzS0hCkAC&q=Hostmask&pg=PA500
| access-date  = 30 March 2010
| edition     = 2nd
| date        = 29 May 2002
| publisher   = [[CRC Press]]
| isbn        = 978-0-8493-1173-4
| page        = 500
| chapter     = Internet Relay Chat
}}</ref> If ident is not available on the client, the username specified when the client connected is used after being prefixed with a [[tilde]].<ref name="freenode faq">{{cite web
| url         = http://freenode.net/faq.shtml
| title         = Frequently-Asked Questions
| access-date         = 30 March 2010
| publisher         = [[freenode]]
| archive-url         = https://web.archive.org/web/20100326082146/http://freenode.net/faq.shtml
| archive-date         = 26 March 2010
| url-status         = dead
}}</ref>

The host part is the [[hostname]] the client is connecting from. If the [[IP address]] of the client cannot be resolved to a valid [[hostname]] by the server, it is used instead of the hostname.

Because of the [[privacy]] implications of exposing the IP address or hostname of a client, some [[IRCd|IRC daemons]] also provide privacy features, such as InspIRCd or UnrealIRCd's "+x" mode. This [[Cryptographic hash function|hashes]] a client IP address or masks part of a client's hostname, making it unreadable to users other than [[#IRC operators|IRCops]]. Users may also have the option of requesting a "virtual host" (or "vhost"), to be displayed in the hostmask to allow further anonymity. Some IRC networks, such as [[Libera Chat]] or [[Freenode]], use these as "cloaks" to indicate that a user is affiliated with a group or project.<ref>{{cite web
| url        = http://meta.wikimedia.org/wiki/IRC/Cloaks
| title      = IRC/Cloaks
| access-date = 27 November 2011
| publisher  = [[Meta-wiki]]
}}</ref>