Editing IRCd (section)

== Configuration ==

=== Jupe ===
'''Juping''' a server, a channel, or a nickname refers to the practice of blocking said channel or nickname on the [[server (computing)|server]] or [[computer network|network]] or said server on the network. One possible explanation of how this term came about is that it is named after the [[IRC operator|oper]] named Jupiter, who gained control of the nickname [[NickServ]] on [[EFnet]].<ref>{{cite web|url=http://forum.efnet.org/viewtopic.php?p=736&sid=93438e76e1948098a2575a7474b56cbd#p736|access-date=2013-03-13|title=Reply to thread "K-lined for {{sic|nolink=y|attemting}} to join juped channel ?" on EFnet forums}}</ref>{{Citation needed|date=September 2009}} EFnet does not offer services such as NickServ; Jupiter gained control of the nickname as he (among other operators) did not believe nicknames should be owned. Today, EFnet opers jupe nicknames that are used as services on other networks.

A nickname or server jupe takes advantage of the fact that certain identifiers are unique; by using an identifier, one acquires an exclusive lock that prevents other users from making use of it.

Officially sanctioned jupes may also utilize services or server configuration options to enforce the jupe, such as when a compromised server is juped to prevent it from harming the network.

In practice IRC operators now use jupe configurations to administratively make channel or nicknames unavailable.<ref>{{cite web|url=http://freenode.net/using_the_network.shtml|access-date=2007-02-25|title=Freenode, Using the network|url-status=dead|archive-url=https://web.archive.org/web/20070226012149/http://freenode.net/using_the_network.shtml|archive-date=2007-02-26}}</ref> A channel jupe refers to a server specific ban of a channel, which means that a specific channel cannot be joined when connected to a certain server, but other servers may allow a user to join the channel. This is a way of banning access to problematic channels.

=== O-line {{anchor|O-line}} ===
An '''O-line''' (frequently also spelled as '''O:line'''{{citation needed|date=March 2013}}; on IRCds that support local operators, the O-lines of those are called '''o:lines''' with a lower-case O{{citation needed|date=March 2013}}), shortened from ''Operator Line'' and derived from the line-based configuration file of the original IRCd, is a line of code in an IRC daemon configuration file that determines which users can become an [[IRC operator]] and which permissions they get upon doing so. The name comes from the prefix used for the line in the original IRCd, a capital O. The O-line specifies the username, password, operator flags, and hostmask restrictions for a particular operator. A server may have many O-lines depending on the administrative needs of the server and network.<ref>[http://docs.dal.net/docs/operinfo.html IRC Operator Version 1.1.2]</ref>

Operator flags are used to describe the permissions an operator is granted. While some IRC operators may be in charge of network routing, others may be in charge of network abuse, making their need for certain permissions different.<ref name=RFC1459 /> Operator flags available vary widely depending on which IRC daemon is in use. Generally, more feature rich IRC daemons tend to have more operator flags, and more traditional IRC daemons have fewer.

An O-line may also be set so that only users of a certain [[hostmask]] or [[IP address]] can gain IRC operator status using that O-line. Using hostmasks and IP addresses in the O-line requires the IP address to remain the same but provides additional security.

=== 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.

=== G-line ===
{{Redirect|G-line}}
A '''G-line''' or '''global kill line''' (also written '''G:line''') is a global network ban applied to a user; the term comes from [[Undernet]] but on [[DALnet]] a similar concept known as an [[AKill]] was used.{{Citation needed|date=February 2019}}

G-lines are sometimes stored in the [[configuration file]] of the IRCd, although some networks, who handle K-lines through the [[IRC services]], prefer to have them stored in their service's configuration files. Whenever a G-lined person attempts to connect to the IRC network, either the services or the IRC daemon will automatically disconnect the client, often displaying a message explaining the reasoning behind the ban.

G-lines are a variant of K-lines, which work in much the same way, except K-lines only disconnect clients on one server of the network. G-lines are normally applied to a user who has received a K-line on one server but continues to abuse the network by connecting via a different server. G-lines are often regarded as an extreme measure, only to be used in cases of repeated abuse when extensive attempts have been made to reason with the offending user. Therefore, especially on larger networks, often only very high ranking global [[IRC operator]]s are permitted to set them, while K-lines, which are mostly regarded as a local affair, are left to the operators of the individual [[server (computing)|server]] in the network.

G-lines also work slightly differently from K-lines. G-lines are typically set as *@IPaddress or *@host, with the first being the better option. If the *@host option is used, the server must conduct a reverse DNS lookup on the user and then compare the returned host to the hosts in the G-line list. This results in delay, and, if the DNS doesn't return correct results, the banned user may still get on the network.

=== Z-line {{anchor|GZ-line|D-line|X-line}} ===
{{Redirect|Zline||Z-line (disambiguation){{!}}Z-line}}
A '''Z-line''' or '''zap line''' (also written '''Z:line''') is similar to a K-line, but applied to a client's IP address range, and is considered to be used in extreme cases. Because a Z-line does not have to check usernames (identd) or ''resolved'' hostnames, it can be applied to a user before they send any data at all upon connection. Therefore, a Z-line is more efficient and uses fewer resources than a K-line or G-line when banning large numbers of users.

In some IRC daemons such as ircd-hybrid, this is called a '''D-line''' (deny line) or an '''X-line'''.

Z-lines are sometimes stored in the configuration file of the IRCd, although some networks, who handle lines through the IRC services, prefer to have them stored in their service's configuration files. Whenever a Z-lined person attempts to connect to the IRC network, either the services or the IRC daemon will automatically disconnect the client, often displaying a message explaining the reasoning behind the ban.

Z-lines are a variant of K-lines, which work in much the same way. Most Z-lines are "awarded" to people who abuse the network as a whole (on smaller networks, these are more frequently issued for isolated incidents).

Z-lines also work slightly differently from K-lines. Z-lines are typically set as *@IP or *@host, with the first being the better option. Z-lines do not wait for an ident response from the connecting user, but immediately close the socket once the user's IP is compared to the Z-line list and a match is found. If the *@host option is used, the server must conduct a reverse DNS lookup on the user and then compare the returned host to the hosts in the Z-line list. This can result in delays, or if the DNS doesn't return correctly, banned users could still get on the network. In actuality, the *@host option is completely against the intentions of using a Z-line, and therefore some IRCd programs will not allow anything other than *@IP, with [[wildcard character|wildcards]] (?,*) or [[Classless Inter-Domain Routing|CIDR prefix lengths]] (''e.g. /8)'' allowed in the IP section to block entire subnets. Another difference from K-lines (which affect only IRC clients) is if an IP is banned, nothing, not even other servers, can connect from this IP (or IP range, depending on the banmask).

One advantage to using Z-lines over K-lines and G-lines, from a server or network administrator's perspective, a Z-line uses less bandwidth than a K-line, mainly because it doesn't wait for an [[ident protocol|ident]] response or [[Domain Name System|DNS]] lookup.

A disadvantage to using Z-line over K-line or G-line is that it becomes more difficult to ban entire ISPs and very dynamic IP addresses, common with some [[dialup]] and [[Digital subscriber line|DSL]] connections. For example, if a network administrator wants to ban all of ISP example.com (with hypothetical [[IP address]] ranges of 68.0.0.0 – 68.255.255.255 and 37.0.0.0 – 38.255.255.255), a G-line could use *@*example.com, whereas Z-line would require *@37.*.*.*, *@38.*.*.*, and *@68.*.*.* to accomplish the same thing.

Z-lines can also be global, in which case they are called '''GZ-lines'''. GZ-lines work in the same manner as Z-lines, except that they propagate to every server on the network. Some IRC daemons may also be configured to share Z-lines with other servers.

=== Q-line ===
{{Redirect|Q-line|the New York City subway service|Q (New York City Subway service)|the Detroit streetcar service|QLine}}
On some IRCds, such as UnrealIRCd, a '''Q-line''' forbids a nickname, or any nickname matching a given pattern. This is most often used to forbid use of services nicknames (such as "X", or [[NickServ]]) or forbid use of [[IRC operator]] nicknames by non-operators. Some IRC daemons may disconnect users when initially applying the Q-line, whilst others will force a nickname change, or do nothing until the user covered by the Q-line reconnects. Other IRCds, like ircd-hybrid, use the "RESV" ("reserve") command instead, with the stats letter remaining as Q. The "RESV" command can also forbid a channel from being used.