USERHOST

Userhost, in networking and chat systems, refers to the combined identity information used to identify a user on a given host. The term is most closely associated with Internet Relay Chat (IRC), where userhost data is used to differentiate users who share a nickname and to facilitate moderation, logging, and access control across channels.

In IRC, the userhost typically takes the form nick!ident@host. The 'nick' is the user's current nickname; 'ident' (also called the ident or user) is the account name; 'host' is the remote host or IP address as seen by the server. Some servers apply host cloaking, replacing the real host with a masked value to protect privacy, while others disclose it for anti-abuse purposes.

The USERHOST command is used to query one or more nicknames for their userhost information. A typical response includes the nick and its hostmask, or a message indicating that the user is no longer online or that access is restricted. The facility helps clients display consistent user identifiers and enables operators to enforce bans or identify duplicates across channels.

Privacy and security concerns include exposure of a user's machine in bare host data. Users can mitigate this through cloaking, using a different ident or through network policies. The concept of userhost is one aspect of broader identity and access controls in chat networks, as well as in other distributed systems that map user identities to hosts.

See also hostmask, ident, IRC.