Editing IRCd (section)

=== K-line ===
When a user is ''k-lined'' (short for '''kill line'''), the user is banned from a certain server, either for a certain amount of time or permanently. Once the user is banned, they are not allowed back onto that server. This is recorded as a line in the server's IRC daemon configuration file prefixed with the letter "K", hence "K-line".

Some IRC daemons, including ircd-hybrid and its descendants, can be configured to propagate K-lines to some or all other servers on a network. In such a configuration, K-lines are effectively global bans similar to G-lines.

While the precise reason for the disconnection varies from case to case, usual reasons involve some aspect of the client or the user it is issued against.

; User behavior
: K-lines can be given due to inappropriate behavior on the part of the user, such as "nickname colliding", mode "hacking", multiple channel flooding, harassing other users via [[private message|private messaging]] features, "[[spamming]]" etc., or in the case of older networks without timestamping, [[split riding]], which cannot be corrected through use of [[Internet Relay Chat channel operator|channel operator]] privileges alone.
; Client software
: Some IRC daemons can be configured to scan for viruses or other vulnerabilities in clients connecting to them, and will react in various ways according to the result. Outdated and insecure client software might be blocked to protect other network users from vulnerabilities, for instance. Some networks will disconnect clients operating on/via open [[proxy server|proxies]], or running an insecure web server.
; Geographic location
: An IRC network operating multiple servers in different locales will attempt to reduce the distance between a client and a server. This is often achieved by disconnecting (and/or banning) clients from distant locales in favour of local ones.

There are a number of other network "lines" relating to the K-line. Modern IRC daemons will also allow IRC operators to set these lines during normal operation, where access to the server configuration file is not routinely needed.