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7 Network Working Group J. Oikarinen
8 Request for Comments: 1459 D. Reed
9 May 1993
12 Internet Relay Chat Protocol
14 Status of This Memo
16 This memo defines an Experimental Protocol for the Internet
17 community. Discussion and suggestions for improvement are requested.
18 Please refer to the current edition of the "IAB Official Protocol
19 Standards" for the standardization state and status of this protocol.
20 Distribution of this memo is unlimited.
22 Abstract
24 The IRC protocol was developed over the last 4 years since it was
25 first implemented as a means for users on a BBS to chat amongst
26 themselves. Now it supports a world-wide network of servers and
27 clients, and is stringing to cope with growth. Over the past 2 years,
28 the average number of users connected to the main IRC network has
29 grown by a factor of 10.
31 The IRC protocol is a text-based protocol, with the simplest client
32 being any socket program capable of connecting to the server.
34 Table of Contents
36 1. INTRODUCTION ............................................... 4
37 1.1 Servers ................................................ 4
38 1.2 Clients ................................................ 5
39 1.2.1 Operators .......................................... 5
40 1.3 Channels ................................................ 5
41 1.3.1 Channel Operators .................................... 6
42 2. THE IRC SPECIFICATION ....................................... 7
43 2.1 Overview ................................................ 7
44 2.2 Character codes ......................................... 7
45 2.3 Messages ................................................ 7
46 2.3.1 Message format in 'pseudo' BNF .................... 8
47 2.4 Numeric replies ......................................... 10
48 3. IRC Concepts ................................................ 10
49 3.1 One-to-one communication ................................ 10
50 3.2 One-to-many ............................................. 11
51 3.2.1 To a list .......................................... 11
52 3.2.2 To a group (channel) ............................... 11
53 3.2.3 To a host/server mask .............................. 12
54 3.3 One to all .............................................. 12
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60 RFC 1459 Internet Relay Chat Protocol May 1993
63 3.3.1 Client to Client ................................... 12
64 3.3.2 Clients to Server .................................. 12
65 3.3.3 Server to Server ................................... 12
66 4. MESSAGE DETAILS ............................................. 13
67 4.1 Connection Registration ................................. 13
68 4.1.1 Password message ................................... 14
69 4.1.2 Nickname message ................................... 14
70 4.1.3 User message ....................................... 15
71 4.1.4 Server message ..................................... 16
72 4.1.5 Operator message ................................... 17
73 4.1.6 Quit message ....................................... 17
74 4.1.7 Server Quit message ................................ 18
75 4.2 Channel operations ...................................... 19
76 4.2.1 Join message ....................................... 19
77 4.2.2 Part message ....................................... 20
78 4.2.3 Mode message ....................................... 21
79 4.2.3.1 Channel modes ................................. 21
80 4.2.3.2 User modes .................................... 22
81 4.2.4 Topic message ...................................... 23
82 4.2.5 Names message ...................................... 24
83 4.2.6 List message ....................................... 24
84 4.2.7 Invite message ..................................... 25
85 4.2.8 Kick message ....................................... 25
86 4.3 Server queries and commands ............................. 26
87 4.3.1 Version message .................................... 26
88 4.3.2 Stats message ...................................... 27
89 4.3.3 Links message ...................................... 28
90 4.3.4 Time message ....................................... 29
91 4.3.5 Connect message .................................... 29
92 4.3.6 Trace message ...................................... 30
93 4.3.7 Admin message ...................................... 31
94 4.3.8 Info message ....................................... 31
95 4.4 Sending messages ........................................ 32
96 4.4.1 Private messages ................................... 32
97 4.4.2 Notice messages .................................... 33
98 4.5 User-based queries ...................................... 33
99 4.5.1 Who query .......................................... 33
100 4.5.2 Whois query ........................................ 34
101 4.5.3 Whowas message ..................................... 35
102 4.6 Miscellaneous messages .................................. 35
103 4.6.1 Kill message ....................................... 36
104 4.6.2 Ping message ....................................... 37
105 4.6.3 Pong message ....................................... 37
106 4.6.4 Error message ...................................... 38
107 5. OPTIONAL MESSAGES ........................................... 38
108 5.1 Away message ............................................ 38
109 5.2 Rehash command .......................................... 39
110 5.3 Restart command ......................................... 39
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119 5.4 Summon message .......................................... 40
120 5.5 Users message ........................................... 40
121 5.6 Operwall command ........................................ 41
122 5.7 Userhost message ........................................ 42
123 5.8 Ison message ............................................ 42
124 6. REPLIES ..................................................... 43
125 6.1 Error Replies ........................................... 43
126 6.2 Command responses ....................................... 48
127 6.3 Reserved numerics ....................................... 56
128 7. Client and server authentication ............................ 56
129 8. Current Implementations Details ............................. 56
130 8.1 Network protocol: TCP ................................... 57
131 8.1.1 Support of Unix sockets ............................ 57
132 8.2 Command Parsing ......................................... 57
133 8.3 Message delivery ........................................ 57
134 8.4 Connection 'Liveness' ................................... 58
135 8.5 Establishing a server-client connection ................. 58
136 8.6 Establishing a server-server connection ................. 58
137 8.6.1 State information exchange when connecting ......... 59
138 8.7 Terminating server-client connections ................... 59
139 8.8 Terminating server-server connections ................... 59
140 8.9 Tracking nickname changes ............................... 60
141 8.10 Flood control of clients ............................... 60
142 8.11 Non-blocking lookups ................................... 61
143 8.11.1 Hostname (DNS) lookups ............................ 61
144 8.11.2 Username (Ident) lookups .......................... 61
145 8.12 Configuration file ..................................... 61
146 8.12.1 Allowing clients to connect ....................... 62
147 8.12.2 Operators ......................................... 62
148 8.12.3 Allowing servers to connect ....................... 62
149 8.12.4 Administrivia ..................................... 63
150 8.13 Channel membership ..................................... 63
151 9. Current problems ............................................ 63
152 9.1 Scalability ............................................. 63
153 9.2 Labels .................................................. 63
154 9.2.1 Nicknames .......................................... 63
155 9.2.2 Channels ........................................... 64
156 9.2.3 Servers ............................................ 64
157 9.3 Algorithms .............................................. 64
158 10. Support and availability ................................... 64
159 11. Security Considerations .................................... 65
160 12. Authors' Addresses ......................................... 65
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175 1. INTRODUCTION
177 The IRC (Internet Relay Chat) protocol has been designed over a
178 number of years for use with text based conferencing. This document
179 describes the current IRC protocol.
181 The IRC protocol has been developed on systems using the TCP/IP
182 network protocol, although there is no requirement that this remain
183 the only sphere in which it operates.
185 IRC itself is a teleconferencing system, which (through the use of
186 the client-server model) is well-suited to running on many machines
187 in a distributed fashion. A typical setup involves a single process
188 (the server) forming a central point for clients (or other servers)
189 to connect to, performing the required message delivery/multiplexing
190 and other functions.
192 1.1 Servers
194 The server forms the backbone of IRC, providing a point to which
195 clients may connect to to talk to each other, and a point for other
196 servers to connect to, forming an IRC network. The only network
197 configuration allowed for IRC servers is that of a spanning tree [see
198 Fig. 1] where each server acts as a central node for the rest of the
199 net it sees.
202 [ Server 15 ] [ Server 13 ] [ Server 14]
203 / \ /
204 / \ /
205 [ Server 11 ] ------ [ Server 1 ] [ Server 12]
206 / \ /
207 / \ /
208 [ Server 2 ] [ Server 3 ]
209 / \ \
210 / \ \
211 [ Server 4 ] [ Server 5 ] [ Server 6 ]
212 / | \ /
213 / | \ /
214 / | \____ /
215 / | \ /
216 [ Server 7 ] [ Server 8 ] [ Server 9 ] [ Server 10 ]
218 :
219 [ etc. ]
220 :
222 [ Fig. 1. Format of IRC server network ]
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231 1.2 Clients
233 A client is anything connecting to a server that is not another
234 server. Each client is distinguished from other clients by a unique
235 nickname having a maximum length of nine (9) characters. See the
236 protocol grammar rules for what may and may not be used in a
237 nickname. In addition to the nickname, all servers must have the
238 following information about all clients: the real name of the host
239 that the client is running on, the username of the client on that
240 host, and the server to which the client is connected.
242 1.2.1 Operators
244 To allow a reasonable amount of order to be kept within the IRC
245 network, a special class of clients (operators) is allowed to perform
246 general maintenance functions on the network. Although the powers
247 granted to an operator can be considered as 'dangerous', they are
248 nonetheless required. Operators should be able to perform basic
249 network tasks such as disconnecting and reconnecting servers as
250 needed to prevent long-term use of bad network routing. In
251 recognition of this need, the protocol discussed herein provides for
252 operators only to be able to perform such functions. See sections
253 4.1.7 (SQUIT) and 4.3.5 (CONNECT).
255 A more controversial power of operators is the ability to remove a
256 user from the connected network by 'force', i.e. operators are able
257 to close the connection between any client and server. The
258 justification for this is delicate since its abuse is both
259 destructive and annoying. For further details on this type of
260 action, see section 4.6.1 (KILL).
262 1.3 Channels
264 A channel is a named group of one or more clients which will all
265 receive messages addressed to that channel. The channel is created
266 implicitly when the first client joins it, and the channel ceases to
267 exist when the last client leaves it. While channel exists, any
268 client can reference the channel using the name of the channel.
270 Channels names are strings (beginning with a '&' or '#' character) of
271 length up to 200 characters. Apart from the the requirement that the
272 first character being either '&' or '#'; the only restriction on a
273 channel name is that it may not contain any spaces (' '), a control G
274 (^G or ASCII 7), or a comma (',' which is used as a list item
275 separator by the protocol).
277 There are two types of channels allowed by this protocol. One is a
278 distributed channel which is known to all the servers that are
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284 RFC 1459 Internet Relay Chat Protocol May 1993
287 connected to the network. These channels are marked by the first
288 character being a only clients on the server where it exists may join
289 it. These are distinguished by a leading '&' character. On top of
290 these two types, there are the various channel modes available to
291 alter the characteristics of individual channels. See section 4.2.3
292 (MODE command) for more details on this.
294 To create a new channel or become part of an existing channel, a user
295 is required to JOIN the channel. If the channel doesn't exist prior
296 to joining, the channel is created and the creating user becomes a
297 channel operator. If the channel already exists, whether or not your
298 request to JOIN that channel is honoured depends on the current modes
299 of the channel. For example, if the channel is invite-only, (+i),
300 then you may only join if invited. As part of the protocol, a user
301 may be a part of several channels at once, but a limit of ten (10)
302 channels is recommended as being ample for both experienced and
303 novice users. See section 8.13 for more information on this.
305 If the IRC network becomes disjoint because of a split between two
306 servers, the channel on each side is only composed of those clients
307 which are connected to servers on the respective sides of the split,
308 possibly ceasing to exist on one side of the split. When the split
309 is healed, the connecting servers announce to each other who they
310 think is in each channel and the mode of that channel. If the
311 channel exists on both sides, the JOINs and MODEs are interpreted in
312 an inclusive manner so that both sides of the new connection will
313 agree about which clients are in the channel and what modes the
314 channel has.
316 1.3.1 Channel Operators
318 The channel operator (also referred to as a "chop" or "chanop") on a
319 given channel is considered to 'own' that channel. In recognition of
320 this status, channel operators are endowed with certain powers which
321 enable them to keep control and some sort of sanity in their channel.
322 As an owner of a channel, a channel operator is not required to have
323 reasons for their actions, although if their actions are generally
324 antisocial or otherwise abusive, it might be reasonable to ask an IRC
325 operator to intervene, or for the usersjust leave and go elsewhere
326 and form their own channel.
328 The commands which may only be used by channel operators are:
330 KICK - Eject a client from the channel
331 MODE - Change the channel's mode
332 INVITE - Invite a client to an invite-only channel (mode +i)
333 TOPIC - Change the channel topic in a mode +t channel
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343 A channel operator is identified by the '@' symbol next to their
344 nickname whenever it is associated with a channel (ie replies to the
345 NAMES, WHO and WHOIS commands).
347 2. The IRC Specification
349 2.1 Overview
351 The protocol as described herein is for use both with server to
352 server and client to server connections. There are, however, more
353 restrictions on client connections (which are considered to be
354 untrustworthy) than on server connections.
356 2.2 Character codes
358 No specific character set is specified. The protocol is based on a a
359 set of codes which are composed of eight (8) bits, making up an
360 octet. Each message may be composed of any number of these octets;
361 however, some octet values are used for control codes which act as
362 message delimiters.
364 Regardless of being an 8-bit protocol, the delimiters and keywords
365 are such that protocol is mostly usable from USASCII terminal and a
366 telnet connection.
368 Because of IRC's scandanavian origin, the characters {}| are
369 considered to be the lower case equivalents of the characters []\,
370 respectively. This is a critical issue when determining the
371 equivalence of two nicknames.
373 2.3 Messages
375 Servers and clients send eachother messages which may or may not
376 generate a reply. If the message contains a valid command, as
377 described in later sections, the client should expect a reply as
378 specified but it is not advised to wait forever for the reply; client
379 to server and server to server communication is essentially
380 asynchronous in nature.
382 Each IRC message may consist of up to three main parts: the prefix
383 (optional), the command, and the command parameters (of which there
384 may be up to 15). The prefix, command, and all parameters are
385 separated by one (or more) ASCII space character(s) (0x20).
387 The presence of a prefix is indicated with a single leading ASCII
388 colon character (':', 0x3b), which must be the first character of the
389 message itself. There must be no gap (whitespace) between the colon
390 and the prefix. The prefix is used by servers to indicate the true
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399 origin of the message. If the prefix is missing from the message, it
400 is assumed to have originated from the connection from which it was
401 received. Clients should not use prefix when sending a message from
402 themselves; if they use a prefix, the only valid prefix is the
403 registered nickname associated with the client. If the source
404 identified by the prefix cannot be found from the server's internal
405 database, or if the source is registered from a different link than
406 from which the message arrived, the server must ignore the message
407 silently.
409 The command must either be a valid IRC command or a three (3) digit
410 number represented in ASCII text.
412 IRC messages are always lines of characters terminated with a CR-LF
413 (Carriage Return - Line Feed) pair, and these messages shall not
414 exceed 512 characters in length, counting all characters including
415 the trailing CR-LF. Thus, there are 510 characters maximum allowed
416 for the command and its parameters. There is no provision for
417 continuation message lines. See section 7 for more details about
418 current implementations.
420 2.3.1 Message format in 'pseudo' BNF
422 The protocol messages must be extracted from the contiguous stream of
423 octets. The current solution is to designate two characters, CR and
424 LF, as message separators. Empty messages are silently ignored,
425 which permits use of the sequence CR-LF between messages
426 without extra problems.
428 The extracted message is parsed into the components <prefix>,
429 <command> and list of parameters matched either by <middle> or
430 <trailing> components.
432 The BNF representation for this is:
435 <message> ::= [':' <prefix> <SPACE> ] <command> <params> <crlf>
436 <prefix> ::= <servername> | <nick> [ '!' <user> ] [ '@' <host> ]
437 <command> ::= <letter> { <letter> } | <number> <number> <number>
438 <SPACE> ::= ' ' { ' ' }
439 <params> ::= <SPACE> [ ':' <trailing> | <middle> <params> ]
441 <middle> ::= <Any *non-empty* sequence of octets not including SPACE
442 or NUL or CR or LF, the first of which may not be ':'>
443 <trailing> ::= <Any, possibly *empty*, sequence of octets not including
444 NUL or CR or LF>
446 <crlf> ::= CR LF
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455 NOTES:
457 1) <SPACE> is consists only of SPACE character(s) (0x20).
458 Specially notice that TABULATION, and all other control
459 characters are considered NON-WHITE-SPACE.
461 2) After extracting the parameter list, all parameters are equal,
462 whether matched by <middle> or <trailing>. <Trailing> is just
463 a syntactic trick to allow SPACE within parameter.
465 3) The fact that CR and LF cannot appear in parameter strings is
466 just artifact of the message framing. This might change later.
468 4) The NUL character is not special in message framing, and
469 basically could end up inside a parameter, but as it would
470 cause extra complexities in normal C string handling. Therefore
471 NUL is not allowed within messages.
473 5) The last parameter may be an empty string.
475 6) Use of the extended prefix (['!' <user> ] ['@' <host> ]) must
476 not be used in server to server communications and is only
477 intended for server to client messages in order to provide
478 clients with more useful information about who a message is
479 from without the need for additional queries.
481 Most protocol messages specify additional semantics and syntax for
482 the extracted parameter strings dictated by their position in the
483 list. For example, many server commands will assume that the first
484 parameter after the command is the list of targets, which can be
485 described with:
487 <target> ::= <to> [ "," <target> ]
488 <to> ::= <channel> | <user> '@' <servername> | <nick> | <mask>
489 <channel> ::= ('#' | '&') <chstring>
490 <servername> ::= <host>
491 <host> ::= see RFC 952 [DNS:4] for details on allowed hostnames
492 <nick> ::= <letter> { <letter> | <number> | <special> }
493 <mask> ::= ('#' | '$') <chstring>
494 <chstring> ::= <any 8bit code except SPACE, BELL, NUL, CR, LF and
495 comma (',')>
497 Other parameter syntaxes are:
499 <user> ::= <nonwhite> { <nonwhite> }
500 <letter> ::= 'a' ... 'z' | 'A' ... 'Z'
501 <number> ::= '0' ... '9'
502 <special> ::= '-' | '[' | ']' | '\' | '`' | '^' | '{' | '}'
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511 <nonwhite> ::= <any 8bit code except SPACE (0x20), NUL (0x0), CR
512 (0xd), and LF (0xa)>
514 2.4 Numeric replies
516 Most of the messages sent to the server generate a reply of some
517 sort. The most common reply is the numeric reply, used for both
518 errors and normal replies. The numeric reply must be sent as one
519 message consisting of the sender prefix, the three digit numeric, and
520 the target of the reply. A numeric reply is not allowed to originate
521 from a client; any such messages received by a server are silently
522 dropped. In all other respects, a numeric reply is just like a normal
523 message, except that the keyword is made up of 3 numeric digits
524 rather than a string of letters. A list of different replies is
525 supplied in section 6.
527 3. IRC Concepts.
529 This section is devoted to describing the actual concepts behind the
530 organization of the IRC protocol and how the current
531 implementations deliver different classes of messages.
535 1--\
536 A D---4
537 2--/ \ /
538 B----C
539 / \
540 3 E
542 Servers: A, B, C, D, E Clients: 1, 2, 3, 4
544 [ Fig. 2. Sample small IRC network ]
546 3.1 One-to-one communication
548 Communication on a one-to-one basis is usually only performed by
549 clients, since most server-server traffic is not a result of servers
550 talking only to each other. To provide a secure means for clients to
551 talk to each other, it is required that all servers be able to send a
552 message in exactly one direction along the spanning tree in order to
553 reach any client. The path of a message being delivered is the
554 shortest path between any two points on the spanning tree.
556 The following examples all refer to Figure 2 above.
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567 Example 1:
568 A message between clients 1 and 2 is only seen by server A, which
569 sends it straight to client 2.
571 Example 2:
572 A message between clients 1 and 3 is seen by servers A & B, and
573 client 3. No other clients or servers are allowed see the message.
575 Example 3:
576 A message between clients 2 and 4 is seen by servers A, B, C & D
577 and client 4 only.
579 3.2 One-to-many
581 The main goal of IRC is to provide a forum which allows easy and
582 efficient conferencing (one to many conversations). IRC offers
583 several means to achieve this, each serving its own purpose.
585 3.2.1 To a list
587 The least efficient style of one-to-many conversation is through
588 clients talking to a 'list' of users. How this is done is almost
589 self explanatory: the client gives a list of destinations to which
590 the message is to be delivered and the server breaks it up and
591 dispatches a separate copy of the message to each given destination.
592 This isn't as efficient as using a group since the destination list
593 is broken up and the dispatch sent without checking to make sure
594 duplicates aren't sent down each path.
596 3.2.2 To a group (channel)
598 In IRC the channel has a role equivalent to that of the multicast
599 group; their existence is dynamic (coming and going as people join
600 and leave channels) and the actual conversation carried out on a
601 channel is only sent to servers which are supporting users on a given
602 channel. If there are multiple users on a server in the same
603 channel, the message text is sent only once to that server and then
604 sent to each client on the channel. This action is then repeated for
605 each client-server combination until the original message has fanned
606 out and reached each member of the channel.
608 The following examples all refer to Figure 2.
610 Example 4:
611 Any channel with 1 client in it. Messages to the channel go to the
612 server and then nowhere else.
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620 RFC 1459 Internet Relay Chat Protocol May 1993
623 Example 5:
624 2 clients in a channel. All messages traverse a path as if they
625 were private messages between the two clients outside a channel.
627 Example 6:
628 Clients 1, 2 and 3 in a channel. All messages to the channel are
629 sent to all clients and only those servers which must be traversed
630 by the message if it were a private message to a single client. If
631 client 1 sends a message, it goes back to client 2 and then via
632 server B to client 3.
634 3.2.3 To a host/server mask
636 To provide IRC operators with some mechanism to send messages to a
637 large body of related users, host and server mask messages are
638 provided. These messages are sent to users whose host or server
639 information match that of the mask. The messages are only sent to
640 locations where users are, in a fashion similar to that of channels.
642 3.3 One-to-all
644 The one-to-all type of message is better described as a broadcast
645 message, sent to all clients or servers or both. On a large network
646 of users and servers, a single message can result in a lot of traffic
647 being sent over the network in an effort to reach all of the desired
648 destinations.
650 For some messages, there is no option but to broadcast it to all
651 servers so that the state information held by each server is
652 reasonably consistent between servers.
654 3.3.1 Client-to-Client
656 There is no class of message which, from a single message, results in
657 a message being sent to every other client.
659 3.3.2 Client-to-Server
661 Most of the commands which result in a change of state information
662 (such as channel membership, channel mode, user status, etc) must be
663 sent to all servers by default, and this distribution may not be
664 changed by the client.
666 3.3.3 Server-to-Server.
668 While most messages between servers are distributed to all 'other'
669 servers, this is only required for any message that affects either a
670 user, channel or server. Since these are the basic items found in
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679 IRC, nearly all messages originating from a server are broadcast to
680 all other connected servers.
682 4. Message details
684 On the following pages are descriptions of each message recognized by
685 the IRC server and client. All commands described in this section
686 must be implemented by any server for this protocol.
688 Where the reply ERR_NOSUCHSERVER is listed, it means that the
689 <server> parameter could not be found. The server must not send any
690 other replies after this for that command.
692 The server to which a client is connected is required to parse the
693 complete message, returning any appropriate errors. If the server
694 encounters a fatal error while parsing a message, an error must be
695 sent back to the client and the parsing terminated. A fatal error
696 may be considered to be incorrect command, a destination which is
697 otherwise unknown to the server (server, nick or channel names fit
698 this category), not enough parameters or incorrect privileges.
700 If a full set of parameters is presented, then each must be checked
701 for validity and appropriate responses sent back to the client. In
702 the case of messages which use parameter lists using the comma as an
703 item separator, a reply must be sent for each item.
705 In the examples below, some messages appear using the full format:
707 :Name COMMAND parameter list
709 Such examples represent a message from "Name" in transit between
710 servers, where it is essential to include the name of the original
711 sender of the message so remote servers may send back a reply along
712 the correct path.
714 4.1 Connection Registration
716 The commands described here are used to register a connection with an
717 IRC server as either a user or a server as well as correctly
718 disconnect.
720 A "PASS" command is not required for either client or server
721 connection to be registered, but it must precede the server message
722 or the latter of the NICK/USER combination. It is strongly
723 recommended that all server connections have a password in order to
724 give some level of security to the actual connections. The
725 recommended order for a client to register is as follows:
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735 1. Pass message
736 2. Nick message
737 3. User message
739 4.1.1 Password message
742 Command: PASS
743 Parameters: <password>
745 The PASS command is used to set a 'connection password'. The
746 password can and must be set before any attempt to register the
747 connection is made. Currently this requires that clients send a PASS
748 command before sending the NICK/USER combination and servers *must*
749 send a PASS command before any SERVER command. The password supplied
750 must match the one contained in the C/N lines (for servers) or I
751 lines (for clients). It is possible to send multiple PASS commands
752 before registering but only the last one sent is used for
753 verification and it may not be changed once registered. Numeric
754 Replies:
756 ERR_NEEDMOREPARAMS ERR_ALREADYREGISTRED
758 Example:
760 PASS secretpasswordhere
762 4.1.2 Nick message
764 Command: NICK
765 Parameters: <nickname> [ <hopcount> ]
767 NICK message is used to give user a nickname or change the previous
768 one. The <hopcount> parameter is only used by servers to indicate
769 how far away a nick is from its home server. A local connection has
770 a hopcount of 0. If supplied by a client, it must be ignored.
772 If a NICK message arrives at a server which already knows about an
773 identical nickname for another client, a nickname collision occurs.
774 As a result of a nickname collision, all instances of the nickname
775 are removed from the server's database, and a KILL command is issued
776 to remove the nickname from all other server's database. If the NICK
777 message causing the collision was a nickname change, then the
778 original (old) nick must be removed as well.
780 If the server recieves an identical NICK from a client which is
781 directly connected, it may issue an ERR_NICKCOLLISION to the local
782 client, drop the NICK command, and not generate any kills.
786 Oikarinen & Reed [Page 14]
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788 RFC 1459 Internet Relay Chat Protocol May 1993
791 Numeric Replies:
793 ERR_NONICKNAMEGIVEN ERR_ERRONEUSNICKNAME
794 ERR_NICKNAMEINUSE ERR_NICKCOLLISION
796 Example:
798 NICK Wiz ; Introducing new nick "Wiz".
800 :WiZ NICK Kilroy ; WiZ changed his nickname to Kilroy.
802 4.1.3 User message
804 Command: USER
805 Parameters: <username> <hostname> <servername> <realname>
807 The USER message is used at the beginning of connection to specify
808 the username, hostname, servername and realname of s new user. It is
809 also used in communication between servers to indicate new user
810 arriving on IRC, since only after both USER and NICK have been
811 received from a client does a user become registered.
813 Between servers USER must to be prefixed with client's NICKname.
814 Note that hostname and servername are normally ignored by the IRC
815 server when the USER command comes from a directly connected client
816 (for security reasons), but they are used in server to server
817 communication. This means that a NICK must always be sent to a
818 remote server when a new user is being introduced to the rest of the
819 network before the accompanying USER is sent.
821 It must be noted that realname parameter must be the last parameter,
822 because it may contain space characters and must be prefixed with a
823 colon (':') to make sure this is recognised as such.
825 Since it is easy for a client to lie about its username by relying
826 solely on the USER message, the use of an "Identity Server" is
827 recommended. If the host which a user connects from has such a
828 server enabled the username is set to that as in the reply from the
829 "Identity Server".
831 Numeric Replies:
833 ERR_NEEDMOREPARAMS ERR_ALREADYREGISTRED
835 Examples:
838 USER guest tolmoon tolsun :Ronnie Reagan
842 Oikarinen & Reed [Page 15]
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844 RFC 1459 Internet Relay Chat Protocol May 1993
847 ; User registering themselves with a
848 username of "guest" and real name
849 "Ronnie Reagan".
852 :testnick USER guest tolmoon tolsun :Ronnie Reagan
853 ; message between servers with the
854 nickname for which the USER command
855 belongs to
857 4.1.4 Server message
859 Command: SERVER
860 Parameters: <servername> <hopcount> <info>
862 The server message is used to tell a server that the other end of a
863 new connection is a server. This message is also used to pass server
864 data over whole net. When a new server is connected to net,
865 information about it be broadcast to the whole network. <hopcount>
866 is used to give all servers some internal information on how far away
867 all servers are. With a full server list, it would be possible to
868 construct a map of the entire server tree, but hostmasks prevent this
869 from being done.
871 The SERVER message must only be accepted from either (a) a connection
872 which is yet to be registered and is attempting to register as a
873 server, or (b) an existing connection to another server, in which
874 case the SERVER message is introducing a new server behind that
875 server.
877 Most errors that occur with the receipt of a SERVER command result in
878 the connection being terminated by the destination host (target
879 SERVER). Error replies are usually sent using the "ERROR" command
880 rather than the numeric since the ERROR command has several useful
881 properties which make it useful here.
883 If a SERVER message is parsed and attempts to introduce a server
884 which is already known to the receiving server, the connection from
885 which that message must be closed (following the correct procedures),
886 since a duplicate route to a server has formed and the acyclic nature
887 of the IRC tree broken.
889 Numeric Replies:
891 ERR_ALREADYREGISTRED
893 Example:
898 Oikarinen & Reed [Page 16]
899 \f
900 RFC 1459 Internet Relay Chat Protocol May 1993
903 SERVER test.oulu.fi 1 :[tolsun.oulu.fi] Experimental server
904 ; New server test.oulu.fi introducing
905 itself and attempting to register. The
906 name in []'s is the hostname for the
907 host running test.oulu.fi.
910 :tolsun.oulu.fi SERVER csd.bu.edu 5 :BU Central Server
911 ; Server tolsun.oulu.fi is our uplink
912 for csd.bu.edu which is 5 hops away.
914 4.1.5 Oper
916 Command: OPER
917 Parameters: <user> <password>
919 OPER message is used by a normal user to obtain operator privileges.
920 The combination of <user> and <password> are required to gain
921 Operator privileges.
923 If the client sending the OPER command supplies the correct password
924 for the given user, the server then informs the rest of the network
925 of the new operator by issuing a "MODE +o" for the clients nickname.
927 The OPER message is client-server only.
929 Numeric Replies:
931 ERR_NEEDMOREPARAMS RPL_YOUREOPER
932 ERR_NOOPERHOST ERR_PASSWDMISMATCH
934 Example:
936 OPER foo bar ; Attempt to register as an operator
937 using a username of "foo" and "bar" as
938 the password.
940 4.1.6 Quit
942 Command: QUIT
943 Parameters: [<Quit message>]
945 A client session is ended with a quit message. The server must close
946 the connection to a client which sends a QUIT message. If a "Quit
947 Message" is given, this will be sent instead of the default message,
948 the nickname.
950 When netsplits (disconnecting of two servers) occur, the quit message
954 Oikarinen & Reed [Page 17]
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956 RFC 1459 Internet Relay Chat Protocol May 1993
959 is composed of the names of two servers involved, separated by a
960 space. The first name is that of the server which is still connected
961 and the second name is that of the server that has become
962 disconnected.
964 If, for some other reason, a client connection is closed without the
965 client issuing a QUIT command (e.g. client dies and EOF occurs
966 on socket), the server is required to fill in the quit message with
967 some sort of message reflecting the nature of the event which
968 caused it to happen.
970 Numeric Replies:
972 None.
974 Examples:
976 QUIT :Gone to have lunch ; Preferred message format.
978 4.1.7 Server quit message
980 Command: SQUIT
981 Parameters: <server> <comment>
983 The SQUIT message is needed to tell about quitting or dead servers.
984 If a server wishes to break the connection to another server it must
985 send a SQUIT message to the other server, using the the name of the
986 other server as the server parameter, which then closes its
987 connection to the quitting server.
989 This command is also available operators to help keep a network of
990 IRC servers connected in an orderly fashion. Operators may also
991 issue an SQUIT message for a remote server connection. In this case,
992 the SQUIT must be parsed by each server inbetween the operator and
993 the remote server, updating the view of the network held by each
994 server as explained below.
996 The <comment> should be supplied by all operators who execute a SQUIT
997 for a remote server (that is not connected to the server they are
998 currently on) so that other operators are aware for the reason of
999 this action. The <comment> is also filled in by servers which may
1000 place an error or similar message here.
1002 Both of the servers which are on either side of the connection being
1003 closed are required to to send out a SQUIT message (to all its other
1004 server connections) for all other servers which are considered to be
1005 behind that link.
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1012 RFC 1459 Internet Relay Chat Protocol May 1993
1015 Similarly, a QUIT message must be sent to the other connected servers
1016 rest of the network on behalf of all clients behind that link. In
1017 addition to this, all channel members of a channel which lost a
1018 member due to the split must be sent a QUIT message.
1020 If a server connection is terminated prematurely (e.g. the server on
1021 the other end of the link died), the server which detects
1022 this disconnection is required to inform the rest of the network
1023 that the connection has closed and fill in the comment field
1024 with something appropriate.
1026 Numeric replies:
1028 ERR_NOPRIVILEGES ERR_NOSUCHSERVER
1030 Example:
1032 SQUIT tolsun.oulu.fi :Bad Link ? ; the server link tolson.oulu.fi has
1033 been terminated because of "Bad Link".
1035 :Trillian SQUIT cm22.eng.umd.edu :Server out of control
1036 ; message from Trillian to disconnect
1037 "cm22.eng.umd.edu" from the net
1038 because "Server out of control".
1040 4.2 Channel operations
1042 This group of messages is concerned with manipulating channels, their
1043 properties (channel modes), and their contents (typically clients).
1044 In implementing these, a number of race conditions are inevitable
1045 when clients at opposing ends of a network send commands which will
1046 ultimately clash. It is also required that servers keep a nickname
1047 history to ensure that wherever a <nick> parameter is given, the
1048 server check its history in case it has recently been changed.
1050 4.2.1 Join message
1052 Command: JOIN
1053 Parameters: <channel>{,<channel>} [<key>{,<key>}]
1055 The JOIN command is used by client to start listening a specific
1056 channel. Whether or not a client is allowed to join a channel is
1057 checked only by the server the client is connected to; all other
1058 servers automatically add the user to the channel when it is received
1059 from other servers. The conditions which affect this are as follows:
1061 1. the user must be invited if the channel is invite-only;
1066 Oikarinen & Reed [Page 19]
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1068 RFC 1459 Internet Relay Chat Protocol May 1993
1071 2. the user's nick/username/hostname must not match any
1072 active bans;
1074 3. the correct key (password) must be given if it is set.
1076 These are discussed in more detail under the MODE command (see
1077 section 4.2.3 for more details).
1079 Once a user has joined a channel, they receive notice about all
1080 commands their server receives which affect the channel. This
1081 includes MODE, KICK, PART, QUIT and of course PRIVMSG/NOTICE. The
1082 JOIN command needs to be broadcast to all servers so that each server
1083 knows where to find the users who are on the channel. This allows
1084 optimal delivery of PRIVMSG/NOTICE messages to the channel.
1086 If a JOIN is successful, the user is then sent the channel's topic
1087 (using RPL_TOPIC) and the list of users who are on the channel (using
1088 RPL_NAMREPLY), which must include the user joining.
1090 Numeric Replies:
1092 ERR_NEEDMOREPARAMS ERR_BANNEDFROMCHAN
1093 ERR_INVITEONLYCHAN ERR_BADCHANNELKEY
1094 ERR_CHANNELISFULL ERR_BADCHANMASK
1095 ERR_NOSUCHCHANNEL ERR_TOOMANYCHANNELS
1096 RPL_TOPIC
1098 Examples:
1100 JOIN #foobar ; join channel #foobar.
1102 JOIN &foo fubar ; join channel &foo using key "fubar".
1104 JOIN #foo,&bar fubar ; join channel #foo using key "fubar"
1105 and &bar using no key.
1107 JOIN #foo,#bar fubar,foobar ; join channel #foo using key "fubar".
1108 and channel #bar using key "foobar".
1110 JOIN #foo,#bar ; join channels #foo and #bar.
1112 :WiZ JOIN #Twilight_zone ; JOIN message from WiZ
1114 4.2.2 Part message
1116 Command: PART
1117 Parameters: <channel>{,<channel>}
1122 Oikarinen & Reed [Page 20]
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1124 RFC 1459 Internet Relay Chat Protocol May 1993
1127 The PART message causes the client sending the message to be removed
1128 from the list of active users for all given channels listed in the
1129 parameter string.
1131 Numeric Replies:
1133 ERR_NEEDMOREPARAMS ERR_NOSUCHCHANNEL
1134 ERR_NOTONCHANNEL
1136 Examples:
1138 PART #twilight_zone ; leave channel "#twilight_zone"
1140 PART #oz-ops,&group5 ; leave both channels "&group5" and
1141 "#oz-ops".
1143 4.2.3 Mode message
1145 Command: MODE
1147 The MODE command is a dual-purpose command in IRC. It allows both
1148 usernames and channels to have their mode changed. The rationale for
1149 this choice is that one day nicknames will be obsolete and the
1150 equivalent property will be the channel.
1152 When parsing MODE messages, it is recommended that the entire message
1153 be parsed first and then the changes which resulted then passed on.
1155 4.2.3.1 Channel modes
1157 Parameters: <channel> {[+|-]|o|p|s|i|t|n|b|v} [<limit>] [<user>]
1158 [<ban mask>]
1160 The MODE command is provided so that channel operators may change the
1161 characteristics of `their' channel. It is also required that servers
1162 be able to change channel modes so that channel operators may be
1163 created.
1165 The various modes available for channels are as follows:
1167 o - give/take channel operator privileges;
1168 p - private channel flag;
1169 s - secret channel flag;
1170 i - invite-only channel flag;
1171 t - topic settable by channel operator only flag;
1172 n - no messages to channel from clients on the outside;
1173 m - moderated channel;
1174 l - set the user limit to channel;
1178 Oikarinen & Reed [Page 21]
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1180 RFC 1459 Internet Relay Chat Protocol May 1993
1183 b - set a ban mask to keep users out;
1184 v - give/take the ability to speak on a moderated channel;
1185 k - set a channel key (password).
1187 When using the 'o' and 'b' options, a restriction on a total of three
1188 per mode command has been imposed. That is, any combination of 'o'
1189 and
1191 4.2.3.2 User modes
1193 Parameters: <nickname> {[+|-]|i|w|s|o}
1195 The user MODEs are typically changes which affect either how the
1196 client is seen by others or what 'extra' messages the client is sent.
1197 A user MODE command may only be accepted if both the sender of the
1198 message and the nickname given as a parameter are both the same.
1200 The available modes are as follows:
1202 i - marks a users as invisible;
1203 s - marks a user for receipt of server notices;
1204 w - user receives wallops;
1205 o - operator flag.
1207 Additional modes may be available later on.
1209 If a user attempts to make themselves an operator using the "+o"
1210 flag, the attempt should be ignored. There is no restriction,
1211 however, on anyone `deopping' themselves (using "-o"). Numeric
1212 Replies:
1214 ERR_NEEDMOREPARAMS RPL_CHANNELMODEIS
1215 ERR_CHANOPRIVSNEEDED ERR_NOSUCHNICK
1216 ERR_NOTONCHANNEL ERR_KEYSET
1217 RPL_BANLIST RPL_ENDOFBANLIST
1218 ERR_UNKNOWNMODE ERR_NOSUCHCHANNEL
1220 ERR_USERSDONTMATCH RPL_UMODEIS
1221 ERR_UMODEUNKNOWNFLAG
1223 Examples:
1225 Use of Channel Modes:
1227 MODE #Finnish +im ; Makes #Finnish channel moderated and
1228 'invite-only'.
1230 MODE #Finnish +o Kilroy ; Gives 'chanop' privileges to Kilroy on
1234 Oikarinen & Reed [Page 22]
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1236 RFC 1459 Internet Relay Chat Protocol May 1993
1239 channel #Finnish.
1241 MODE #Finnish +v Wiz ; Allow WiZ to speak on #Finnish.
1243 MODE #Fins -s ; Removes 'secret' flag from channel
1244 #Fins.
1246 MODE #42 +k oulu ; Set the channel key to "oulu".
1248 MODE #eu-opers +l 10 ; Set the limit for the number of users
1249 on channel to 10.
1251 MODE &oulu +b ; list ban masks set for channel.
1253 MODE &oulu +b *!*@* ; prevent all users from joining.
1255 MODE &oulu +b *!*@*.edu ; prevent any user from a hostname
1256 matching *.edu from joining.
1258 Use of user Modes:
1260 :MODE WiZ -w ; turns reception of WALLOPS messages
1261 off for WiZ.
1263 :Angel MODE Angel +i ; Message from Angel to make themselves
1264 invisible.
1266 MODE WiZ -o ; WiZ 'deopping' (removing operator
1267 status). The plain reverse of this
1268 command ("MODE WiZ +o") must not be
1269 allowed from users since would bypass
1270 the OPER command.
1272 4.2.4 Topic message
1274 Command: TOPIC
1275 Parameters: <channel> [<topic>]
1277 The TOPIC message is used to change or view the topic of a channel.
1278 The topic for channel <channel> is returned if there is no <topic>
1279 given. If the <topic> parameter is present, the topic for that
1280 channel will be changed, if the channel modes permit this action.
1282 Numeric Replies:
1284 ERR_NEEDMOREPARAMS ERR_NOTONCHANNEL
1285 RPL_NOTOPIC RPL_TOPIC
1286 ERR_CHANOPRIVSNEEDED
1290 Oikarinen & Reed [Page 23]
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1292 RFC 1459 Internet Relay Chat Protocol May 1993
1295 Examples:
1297 :Wiz TOPIC #test :New topic ;User Wiz setting the topic.
1299 TOPIC #test :another topic ;set the topic on #test to "another
1300 topic".
1302 TOPIC #test ; check the topic for #test.
1304 4.2.5 Names message
1306 Command: NAMES
1307 Parameters: [<channel>{,<channel>}]
1309 By using the NAMES command, a user can list all nicknames that are
1310 visible to them on any channel that they can see. Channel names
1311 which they can see are those which aren't private (+p) or secret (+s)
1312 or those which they are actually on. The <channel> parameter
1313 specifies which channel(s) to return information about if valid.
1314 There is no error reply for bad channel names.
1316 If no <channel> parameter is given, a list of all channels and their
1317 occupants is returned. At the end of this list, a list of users who
1318 are visible but either not on any channel or not on a visible channel
1319 are listed as being on `channel' "*".
1321 Numerics:
1323 RPL_NAMREPLY RPL_ENDOFNAMES
1325 Examples:
1327 NAMES #twilight_zone,#42 ; list visible users on #twilight_zone
1328 and #42 if the channels are visible to
1329 you.
1331 NAMES ; list all visible channels and users
1333 4.2.6 List message
1335 Command: LIST
1336 Parameters: [<channel>{,<channel>} [<server>]]
1338 The list message is used to list channels and their topics. If the
1339 <channel> parameter is used, only the status of that channel
1340 is displayed. Private channels are listed (without their
1341 topics) as channel "Prv" unless the client generating the query is
1342 actually on that channel. Likewise, secret channels are not listed
1346 Oikarinen & Reed [Page 24]
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1348 RFC 1459 Internet Relay Chat Protocol May 1993
1351 at all unless the client is a member of the channel in question.
1353 Numeric Replies:
1355 ERR_NOSUCHSERVER RPL_LISTSTART
1356 RPL_LIST RPL_LISTEND
1358 Examples:
1360 LIST ; List all channels.
1362 LIST #twilight_zone,#42 ; List channels #twilight_zone and #42
1364 4.2.7 Invite message
1366 Command: INVITE
1367 Parameters: <nickname> <channel>
1369 The INVITE message is used to invite users to a channel. The
1370 parameter <nickname> is the nickname of the person to be invited to
1371 the target channel <channel>. There is no requirement that the
1372 channel the target user is being invited to must exist or be a valid
1373 channel. To invite a user to a channel which is invite only (MODE
1374 +i), the client sending the invite must be recognised as being a
1375 channel operator on the given channel.
1377 Numeric Replies:
1379 ERR_NEEDMOREPARAMS ERR_NOSUCHNICK
1380 ERR_NOTONCHANNEL ERR_USERONCHANNEL
1381 ERR_CHANOPRIVSNEEDED
1382 RPL_INVITING RPL_AWAY
1384 Examples:
1386 :Angel INVITE Wiz #Dust ; User Angel inviting WiZ to channel
1387 #Dust
1389 INVITE Wiz #Twilight_Zone ; Command to invite WiZ to
1390 #Twilight_zone
1392 4.2.8 Kick command
1394 Command: KICK
1395 Parameters: <channel> <user> [<comment>]
1397 The KICK command can be used to forcibly remove a user from a
1398 channel. It 'kicks them out' of the channel (forced PART).
1402 Oikarinen & Reed [Page 25]
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1404 RFC 1459 Internet Relay Chat Protocol May 1993
1407 Only a channel operator may kick another user out of a channel.
1408 Each server that receives a KICK message checks that it is valid
1409 (ie the sender is actually a channel operator) before removing
1410 the victim from the channel.
1412 Numeric Replies:
1414 ERR_NEEDMOREPARAMS ERR_NOSUCHCHANNEL
1415 ERR_BADCHANMASK ERR_CHANOPRIVSNEEDED
1416 ERR_NOTONCHANNEL
1418 Examples:
1420 KICK &Melbourne Matthew ; Kick Matthew from &Melbourne
1422 KICK #Finnish John :Speaking English
1423 ; Kick John from #Finnish using
1424 "Speaking English" as the reason
1425 (comment).
1427 :WiZ KICK #Finnish John ; KICK message from WiZ to remove John
1428 from channel #Finnish
1430 NOTE:
1431 It is possible to extend the KICK command parameters to the
1432 following:
1434 <channel>{,<channel>} <user>{,<user>} [<comment>]
1436 4.3 Server queries and commands
1438 The server query group of commands has been designed to return
1439 information about any server which is connected to the network. All
1440 servers connected must respond to these queries and respond
1441 correctly. Any invalid response (or lack thereof) must be considered
1442 a sign of a broken server and it must be disconnected/disabled as
1443 soon as possible until the situation is remedied.
1445 In these queries, where a parameter appears as "<server>", it will
1446 usually mean it can be a nickname or a server or a wildcard name of
1447 some sort. For each parameter, however, only one query and set of
1448 replies is to be generated.
1450 4.3.1 Version message
1452 Command: VERSION
1453 Parameters: [<server>]
1458 Oikarinen & Reed [Page 26]
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1460 RFC 1459 Internet Relay Chat Protocol May 1993
1463 The VERSION message is used to query the version of the server
1464 program. An optional parameter <server> is used to query the version
1465 of the server program which a client is not directly connected to.
1467 Numeric Replies:
1469 ERR_NOSUCHSERVER RPL_VERSION
1471 Examples:
1473 :Wiz VERSION *.se ; message from Wiz to check the version
1474 of a server matching "*.se"
1476 VERSION tolsun.oulu.fi ; check the version of server
1477 "tolsun.oulu.fi".
1479 4.3.2 Stats message
1481 Command: STATS
1482 Parameters: [<query> [<server>]]
1484 The stats message is used to query statistics of certain server. If
1485 <server> parameter is omitted, only the end of stats reply is sent
1486 back. The implementation of this command is highly dependent on the
1487 server which replies, although the server must be able to supply
1488 information as described by the queries below (or similar).
1490 A query may be given by any single letter which is only checked by
1491 the destination server (if given as the <server> parameter) and is
1492 otherwise passed on by intermediate servers, ignored and unaltered.
1493 The following queries are those found in the current IRC
1494 implementation and provide a large portion of the setup information
1495 for that server. Although these may not be supported in the same way
1496 by other versions, all servers should be able to supply a valid reply
1497 to a STATS query which is consistent with the reply formats currently
1498 used and the purpose of the query.
1500 The currently supported queries are:
1502 c - returns a list of servers which the server may connect
1503 to or allow connections from;
1504 h - returns a list of servers which are either forced to be
1505 treated as leaves or allowed to act as hubs;
1506 i - returns a list of hosts which the server allows a client
1507 to connect from;
1508 k - returns a list of banned username/hostname combinations
1509 for that server;
1510 l - returns a list of the server's connections, showing how
1514 Oikarinen & Reed [Page 27]
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1516 RFC 1459 Internet Relay Chat Protocol May 1993
1519 long each connection has been established and the traffic
1520 over that connection in bytes and messages for each
1521 direction;
1522 m - returns a list of commands supported by the server and
1523 the usage count for each if the usage count is non zero;
1524 o - returns a list of hosts from which normal clients may
1525 become operators;
1526 y - show Y (Class) lines from server's configuration file;
1527 u - returns a string showing how long the server has been up.
1529 Numeric Replies:
1531 ERR_NOSUCHSERVER
1532 RPL_STATSCLINE RPL_STATSNLINE
1533 RPL_STATSILINE RPL_STATSKLINE
1534 RPL_STATSQLINE RPL_STATSLLINE
1535 RPL_STATSLINKINFO RPL_STATSUPTIME
1536 RPL_STATSCOMMANDS RPL_STATSOLINE
1537 RPL_STATSHLINE RPL_ENDOFSTATS
1539 Examples:
1541 STATS m ; check the command usage for the server
1542 you are connected to
1544 :Wiz STATS c eff.org ; request by WiZ for C/N line
1545 information from server eff.org
1547 4.3.3 Links message
1549 Command: LINKS
1550 Parameters: [[<remote server>] <server mask>]
1552 With LINKS, a user can list all servers which are known by the server
1553 answering the query. The returned list of servers must match the
1554 mask, or if no mask is given, the full list is returned.
1556 If <remote server> is given in addition to <server mask>, the LINKS
1557 command is forwarded to the first server found that matches that name
1558 (if any), and that server is then required to answer the query.
1560 Numeric Replies:
1562 ERR_NOSUCHSERVER
1563 RPL_LINKS RPL_ENDOFLINKS
1565 Examples:
1570 Oikarinen & Reed [Page 28]
1571 \f
1572 RFC 1459 Internet Relay Chat Protocol May 1993
1575 LINKS *.au ; list all servers which have a name
1576 that matches *.au;
1578 :WiZ LINKS *.bu.edu *.edu ; LINKS message from WiZ to the first
1579 server matching *.edu for a list of
1580 servers matching *.bu.edu.
1582 4.3.4 Time message
1584 Command: TIME
1585 Parameters: [<server>]
1587 The time message is used to query local time from the specified
1588 server. If the server parameter is not given, the server handling the
1589 command must reply to the query.
1591 Numeric Replies:
1593 ERR_NOSUCHSERVER RPL_TIME
1595 Examples:
1597 TIME tolsun.oulu.fi ; check the time on the server
1598 "tolson.oulu.fi"
1600 Angel TIME *.au ; user angel checking the time on a
1601 server matching "*.au"
1603 4.3.5 Connect message
1605 Command: CONNECT
1606 Parameters: <target server> [<port> [<remote server>]]
1608 The CONNECT command can be used to force a server to try to establish
1609 a new connection to another server immediately. CONNECT is a
1610 privileged command and is to be available only to IRC Operators. If
1611 a remote server is given then the CONNECT attempt is made by that
1612 server to <target server> and <port>.
1614 Numeric Replies:
1616 ERR_NOSUCHSERVER ERR_NOPRIVILEGES
1617 ERR_NEEDMOREPARAMS
1619 Examples:
1621 CONNECT tolsun.oulu.fi ; Attempt to connect a server to
1622 tolsun.oulu.fi
1626 Oikarinen & Reed [Page 29]
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1628 RFC 1459 Internet Relay Chat Protocol May 1993
1631 :WiZ CONNECT eff.org 6667 csd.bu.edu
1632 ; CONNECT attempt by WiZ to get servers
1633 eff.org and csd.bu.edu connected on port
1634 6667.
1636 4.3.6 Trace message
1638 Command: TRACE
1639 Parameters: [<server>]
1641 TRACE command is used to find the route to specific server. Each
1642 server that processes this message must tell the sender about it by
1643 sending a reply indicating it is a pass-through link, forming a chain
1644 of replies similar to that gained from using "traceroute". After
1645 sending this reply back, it must then send the TRACE message to the
1646 next server until given server is reached. If the <server> parameter
1647 is omitted, it is recommended that TRACE command send a message to
1648 the sender telling which servers the current server has direct
1649 connection to.
1651 If the destination given by "<server>" is an actual server, then the
1652 destination server is required to report all servers and users which
1653 are connected to it, although only operators are permitted to see
1654 users present. If the destination given by <server> is a nickname,
1655 they only a reply for that nickname is given.
1657 Numeric Replies:
1659 ERR_NOSUCHSERVER
1661 If the TRACE message is destined for another server, all intermediate
1662 servers must return a RPL_TRACELINK reply to indicate that the TRACE
1663 passed through it and where its going next.
1665 RPL_TRACELINK
1666 A TRACE reply may be composed of any number of the following numeric
1667 replies.
1669 RPL_TRACECONNECTING RPL_TRACEHANDSHAKE
1670 RPL_TRACEUNKNOWN RPL_TRACEOPERATOR
1671 RPL_TRACEUSER RPL_TRACESERVER
1672 RPL_TRACESERVICE RPL_TRACENEWTYPE
1673 RPL_TRACECLASS
1675 Examples:
1677 TRACE *.oulu.fi ; TRACE to a server matching *.oulu.fi
1682 Oikarinen & Reed [Page 30]
1683 \f
1684 RFC 1459 Internet Relay Chat Protocol May 1993
1687 :WiZ TRACE AngelDust ; TRACE issued by WiZ to nick AngelDust
1689 4.3.7 Admin command
1691 Command: ADMIN
1692 Parameters: [<server>]
1694 The admin message is used to find the name of the administrator of
1695 the given server, or current server if <server> parameter is omitted.
1696 Each server must have the ability to forward ADMIN messages to other
1697 servers.
1699 Numeric Replies:
1701 ERR_NOSUCHSERVER
1702 RPL_ADMINME RPL_ADMINLOC1
1703 RPL_ADMINLOC2 RPL_ADMINEMAIL
1705 Examples:
1707 ADMIN tolsun.oulu.fi ; request an ADMIN reply from
1708 tolsun.oulu.fi
1710 :WiZ ADMIN *.edu ; ADMIN request from WiZ for first
1711 server found to match *.edu.
1713 4.3.8 Info command
1715 Command: INFO
1716 Parameters: [<server>]
1718 The INFO command is required to return information which describes
1719 the server: its version, when it was compiled, the patchlevel, when
1720 it was started, and any other miscellaneous information which may be
1721 considered to be relevant.
1723 Numeric Replies:
1725 ERR_NOSUCHSERVER
1726 RPL_INFO RPL_ENDOFINFO
1728 Examples:
1730 INFO csd.bu.edu ; request an INFO reply from
1731 csd.bu.edu
1733 :Avalon INFO *.fi ; INFO request from Avalon for first
1734 server found to match *.fi.
1738 Oikarinen & Reed [Page 31]
1739 \f
1740 RFC 1459 Internet Relay Chat Protocol May 1993
1743 INFO Angel ; request info from the server that
1744 Angel is connected to.
1746 4.4 Sending messages
1748 The main purpose of the IRC protocol is to provide a base for clients
1749 to communicate with each other. PRIVMSG and NOTICE are the only
1750 messages available which actually perform delivery of a text message
1751 from one client to another - the rest just make it possible and try
1752 to ensure it happens in a reliable and structured manner.
1754 4.4.1 Private messages
1756 Command: PRIVMSG
1757 Parameters: <receiver>{,<receiver>} <text to be sent>
1759 PRIVMSG is used to send private messages between users. <receiver>
1760 is the nickname of the receiver of the message. <receiver> can also
1761 be a list of names or channels separated with commas.
1763 The <receiver> parameter may also me a host mask (#mask) or server
1764 mask ($mask). In both cases the server will only send the PRIVMSG
1765 to those who have a server or host matching the mask. The mask must
1766 have at least 1 (one) "." in it and no wildcards following the
1767 last ".". This requirement exists to prevent people sending messages
1768 to "#*" or "$*", which would broadcast to all users; from
1769 experience, this is abused more than used responsibly and properly.
1770 Wildcards are the '*' and '?' characters. This extension to
1771 the PRIVMSG command is only available to Operators.
1773 Numeric Replies:
1775 ERR_NORECIPIENT ERR_NOTEXTTOSEND
1776 ERR_CANNOTSENDTOCHAN ERR_NOTOPLEVEL
1777 ERR_WILDTOPLEVEL ERR_TOOMANYTARGETS
1778 ERR_NOSUCHNICK
1779 RPL_AWAY
1781 Examples:
1783 :Angel PRIVMSG Wiz :Hello are you receiving this message ?
1784 ; Message from Angel to Wiz.
1786 PRIVMSG Angel :yes I'm receiving it !receiving it !'u>(768u+1n) .br ;
1787 Message to Angel.
1789 PRIVMSG jto@tolsun.oulu.fi :Hello !
1790 ; Message to a client on server
1794 Oikarinen & Reed [Page 32]
1795 \f
1796 RFC 1459 Internet Relay Chat Protocol May 1993
1799 tolsun.oulu.fi with username of "jto".
1801 PRIVMSG $*.fi :Server tolsun.oulu.fi rebooting.
1802 ; Message to everyone on a server which
1803 has a name matching *.fi.
1805 PRIVMSG #*.edu :NSFNet is undergoing work, expect interruptions
1806 ; Message to all users who come from a
1807 host which has a name matching *.edu.
1809 4.4.2 Notice
1811 Command: NOTICE
1812 Parameters: <nickname> <text>
1814 The NOTICE message is used similarly to PRIVMSG. The difference
1815 between NOTICE and PRIVMSG is that automatic replies must never be
1816 sent in response to a NOTICE message. This rule applies to servers
1817 too - they must not send any error reply back to the client on
1818 receipt of a notice. The object of this rule is to avoid loops
1819 between a client automatically sending something in response to
1820 something it received. This is typically used by automatons (clients
1821 with either an AI or other interactive program controlling their
1822 actions) which are always seen to be replying lest they end up in a
1823 loop with another automaton.
1825 See PRIVMSG for more details on replies and examples.
1827 4.5 User based queries
1829 User queries are a group of commands which are primarily concerned
1830 with finding details on a particular user or group users. When using
1831 wildcards with any of these commands, if they match, they will only
1832 return information on users who are 'visible' to you. The visibility
1833 of a user is determined as a combination of the user's mode and the
1834 common set of channels you are both on.
1836 4.5.1 Who query
1838 Command: WHO
1839 Parameters: [<name> [<o>]]
1841 The WHO message is used by a client to generate a query which returns
1842 a list of information which 'matches' the <name> parameter given by
1843 the client. In the absence of the <name> parameter, all visible
1844 (users who aren't invisible (user mode +i) and who don't have a
1845 common channel with the requesting client) are listed. The same
1846 result can be achieved by using a <name> of "0" or any wildcard which
1850 Oikarinen & Reed [Page 33]
1851 \f
1852 RFC 1459 Internet Relay Chat Protocol May 1993
1855 will end up matching every entry possible.
1857 The <name> passed to WHO is matched against users' host, server, real
1858 name and nickname if the channel <name> cannot be found.
1860 If the "o" parameter is passed only operators are returned according
1861 to the name mask supplied.
1863 Numeric Replies:
1865 ERR_NOSUCHSERVER
1866 RPL_WHOREPLY RPL_ENDOFWHO
1868 Examples:
1870 WHO *.fi ; List all users who match against
1871 "*.fi".
1873 WHO jto* o ; List all users with a match against
1874 "jto*" if they are an operator.
1876 4.5.2 Whois query
1878 Command: WHOIS
1879 Parameters: [<server>] <nickmask>[,<nickmask>[,...]]
1881 This message is used to query information about particular user. The
1882 server will answer this message with several numeric messages
1883 indicating different statuses of each user which matches the nickmask
1884 (if you are entitled to see them). If no wildcard is present in the
1885 <nickmask>, any information about that nick which you are allowed to
1886 see is presented. A comma (',') separated list of nicknames may be
1887 given.
1889 The latter version sends the query to a specific server. It is
1890 useful if you want to know how long the user in question has been
1891 idle as only local server (ie. the server the user is directly
1892 connected to) knows that information, while everything else is
1893 globally known.
1895 Numeric Replies:
1897 ERR_NOSUCHSERVER ERR_NONICKNAMEGIVEN
1898 RPL_WHOISUSER RPL_WHOISCHANNELS
1899 RPL_WHOISCHANNELS RPL_WHOISSERVER
1900 RPL_AWAY RPL_WHOISOPERATOR
1901 RPL_WHOISIDLE ERR_NOSUCHNICK
1902 RPL_ENDOFWHOIS
1906 Oikarinen & Reed [Page 34]
1907 \f
1908 RFC 1459 Internet Relay Chat Protocol May 1993
1911 Examples:
1913 WHOIS wiz ; return available user information
1914 about nick WiZ
1916 WHOIS eff.org trillian ; ask server eff.org for user
1917 information about trillian
1919 4.5.3 Whowas
1921 Command: WHOWAS
1922 Parameters: <nickname> [<count> [<server>]]
1924 Whowas asks for information about a nickname which no longer exists.
1925 This may either be due to a nickname change or the user leaving IRC.
1926 In response to this query, the server searches through its nickname
1927 history, looking for any nicks which are lexically the same (no wild
1928 card matching here). The history is searched backward, returning the
1929 most recent entry first. If there are multiple entries, up to
1930 <count> replies will be returned (or all of them if no <count>
1931 parameter is given). If a non-positive number is passed as being
1932 <count>, then a full search is done.
1934 Numeric Replies:
1936 ERR_NONICKNAMEGIVEN ERR_WASNOSUCHNICK
1937 RPL_WHOWASUSER RPL_WHOISSERVER
1938 RPL_ENDOFWHOWAS
1940 Examples:
1942 WHOWAS Wiz ; return all information in the nick
1943 history about nick "WiZ";
1945 WHOWAS Mermaid 9 ; return at most, the 9 most recent
1946 entries in the nick history for
1947 "Mermaid";
1949 WHOWAS Trillian 1 *.edu ; return the most recent history for
1950 "Trillian" from the first server found
1951 to match "*.edu".
1953 4.6 Miscellaneous messages
1955 Messages in this category do not fit into any of the above categories
1956 but are nonetheless still a part of and required by the protocol.
1962 Oikarinen & Reed [Page 35]
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1964 RFC 1459 Internet Relay Chat Protocol May 1993
1967 4.6.1 Kill message
1969 Command: KILL
1970 Parameters: <nickname> <comment>
1972 The KILL message is used to cause a client-server connection to be
1973 closed by the server which has the actual connection. KILL is used
1974 by servers when they encounter a duplicate entry in the list of valid
1975 nicknames and is used to remove both entries. It is also available
1976 to operators.
1978 Clients which have automatic reconnect algorithms effectively make
1979 this command useless since the disconnection is only brief. It does
1980 however break the flow of data and can be used to stop large amounts
1981 of being abused, any user may elect to receive KILL messages
1982 generated for others to keep an 'eye' on would be trouble spots.
1984 In an arena where nicknames are required to be globally unique at all
1985 times, KILL messages are sent whenever 'duplicates' are detected
1986 (that is an attempt to register two users with the same nickname) in
1987 the hope that both of them will disappear and only 1 reappear.
1989 The comment given must reflect the actual reason for the KILL. For
1990 server-generated KILLs it usually is made up of details concerning
1991 the origins of the two conflicting nicknames. For users it is left
1992 up to them to provide an adequate reason to satisfy others who see
1993 it. To prevent/discourage fake KILLs from being generated to hide
1994 the identify of the KILLer, the comment also shows a 'kill-path'
1995 which is updated by each server it passes through, each prepending
1996 its name to the path.
1998 Numeric Replies:
2000 ERR_NOPRIVILEGES ERR_NEEDMOREPARAMS
2001 ERR_NOSUCHNICK ERR_CANTKILLSERVER
2004 KILL David (csd.bu.edu <- tolsun.oulu.fi)
2005 ; Nickname collision between csd.bu.edu
2006 and tolson.oulu.fi
2009 NOTE:
2010 It is recommended that only Operators be allowed to kill other users
2011 with KILL message. In an ideal world not even operators would need
2012 to do this and it would be left to servers to deal with.
2018 Oikarinen & Reed [Page 36]
2019 \f
2020 RFC 1459 Internet Relay Chat Protocol May 1993
2023 4.6.2 Ping message
2025 Command: PING
2026 Parameters: <server1> [<server2>]
2028 The PING message is used to test the presence of an active client at
2029 the other end of the connection. A PING message is sent at regular
2030 intervals if no other activity detected coming from a connection. If
2031 a connection fails to respond to a PING command within a set amount
2032 of time, that connection is closed.
2034 Any client which receives a PING message must respond to <server1>
2035 (server which sent the PING message out) as quickly as possible with
2036 an appropriate PONG message to indicate it is still there and alive.
2037 Servers should not respond to PING commands but rely on PINGs from
2038 the other end of the connection to indicate the connection is alive.
2039 If the <server2> parameter is specified, the PING message gets
2040 forwarded there.
2042 Numeric Replies:
2044 ERR_NOORIGIN ERR_NOSUCHSERVER
2046 Examples:
2048 PING tolsun.oulu.fi ; server sending a PING message to
2049 another server to indicate it is still
2050 alive.
2052 PING WiZ ; PING message being sent to nick WiZ
2054 4.6.3 Pong message
2056 Command: PONG
2057 Parameters: <daemon> [<daemon2>]
2059 PONG message is a reply to ping message. If parameter <daemon2> is
2060 given this message must be forwarded to given daemon. The <daemon>
2061 parameter is the name of the daemon who has responded to PING message
2062 and generated this message.
2064 Numeric Replies:
2066 ERR_NOORIGIN ERR_NOSUCHSERVER
2068 Examples:
2070 PONG csd.bu.edu tolsun.oulu.fi ; PONG message from csd.bu.edu to
2074 Oikarinen & Reed [Page 37]
2075 \f
2076 RFC 1459 Internet Relay Chat Protocol May 1993
2079 tolsun.oulu.fi
2081 4.6.4 Error
2083 Command: ERROR
2084 Parameters: <error message>
2086 The ERROR command is for use by servers when reporting a serious or
2087 fatal error to its operators. It may also be sent from one server to
2088 another but must not be accepted from any normal unknown clients.
2090 An ERROR message is for use for reporting errors which occur with a
2091 server-to-server link only. An ERROR message is sent to the server
2092 at the other end (which sends it to all of its connected operators)
2093 and to all operators currently connected. It is not to be passed
2094 onto any other servers by a server if it is received from a server.
2096 When a server sends a received ERROR message to its operators, the
2097 message should be encapsulated inside a NOTICE message, indicating
2098 that the client was not responsible for the error.
2100 Numerics:
2102 None.
2104 Examples:
2106 ERROR :Server *.fi already exists; ERROR message to the other server
2107 which caused this error.
2109 NOTICE WiZ :ERROR from csd.bu.edu -- Server *.fi already exists
2110 ; Same ERROR message as above but sent
2111 to user WiZ on the other server.
2113 5. OPTIONALS
2115 This section describes OPTIONAL messages. They are not required in a
2116 working server implementation of the protocol described herein. In
2117 the absence of the option, an error reply message must be generated
2118 or an unknown command error. If the message is destined for another
2119 server to answer then it must be passed on (elementary parsing
2120 required) The allocated numerics for this are listed with the
2121 messages below.
2123 5.1 Away
2125 Command: AWAY
2126 Parameters: [message]
2130 Oikarinen & Reed [Page 38]
2131 \f
2132 RFC 1459 Internet Relay Chat Protocol May 1993
2135 With the AWAY message, clients can set an automatic reply string for
2136 any PRIVMSG commands directed at them (not to a channel they are on).
2137 The automatic reply is sent by the server to client sending the
2138 PRIVMSG command. The only replying server is the one to which the
2139 sending client is connected to.
2141 The AWAY message is used either with one parameter (to set an AWAY
2142 message) or with no parameters (to remove the AWAY message).
2144 Numeric Replies:
2146 RPL_UNAWAY RPL_NOWAWAY
2148 Examples:
2150 AWAY :Gone to lunch. Back in 5 ; set away message to "Gone to lunch.
2151 Back in 5".
2153 :WiZ AWAY ; unmark WiZ as being away.
2156 5.2 Rehash message
2158 Command: REHASH
2159 Parameters: None
2161 The rehash message can be used by the operator to force the server to
2162 re-read and process its configuration file.
2164 Numeric Replies:
2166 RPL_REHASHING ERR_NOPRIVILEGES
2168 Examples:
2170 REHASH ; message from client with operator
2171 status to server asking it to reread its
2172 configuration file.
2174 5.3 Restart message
2176 Command: RESTART
2177 Parameters: None
2179 The restart message can only be used by an operator to force a server
2180 restart itself. This message is optional since it may be viewed as a
2181 risk to allow arbitrary people to connect to a server as an operator
2182 and execute this command, causing (at least) a disruption to service.
2186 Oikarinen & Reed [Page 39]
2187 \f
2188 RFC 1459 Internet Relay Chat Protocol May 1993
2191 The RESTART command must always be fully processed by the server to
2192 which the sending client is connected and not be passed onto other
2193 connected servers.
2195 Numeric Replies:
2197 ERR_NOPRIVILEGES
2199 Examples:
2201 RESTART ; no parameters required.
2203 5.4 Summon message
2205 Command: SUMMON
2206 Parameters: <user> [<server>]
2208 The SUMMON command can be used to give users who are on a host
2209 running an IRC server a message asking them to please join IRC. This
2210 message is only sent if the target server (a) has SUMMON enabled, (b)
2211 the user is logged in and (c) the server process can write to the
2212 user's tty (or similar).
2214 If no <server> parameter is given it tries to summon <user> from the
2215 server the client is connected to is assumed as the target.
2217 If summon is not enabled in a server, it must return the
2218 ERR_SUMMONDISABLED numeric and pass the summon message onwards.
2220 Numeric Replies:
2222 ERR_NORECIPIENT ERR_FILEERROR
2223 ERR_NOLOGIN ERR_NOSUCHSERVER
2224 RPL_SUMMONING
2226 Examples:
2228 SUMMON jto ; summon user jto on the server's host
2230 SUMMON jto tolsun.oulu.fi ; summon user jto on the host which a
2231 server named "tolsun.oulu.fi" is
2232 running.
2235 5.5 Users
2237 Command: USERS
2238 Parameters: [<server>]
2242 Oikarinen & Reed [Page 40]
2243 \f
2244 RFC 1459 Internet Relay Chat Protocol May 1993
2247 The USERS command returns a list of users logged into the server in a
2248 similar format to who(1), rusers(1) and finger(1). Some people
2249 may disable this command on their server for security related
2250 reasons. If disabled, the correct numeric must be returned to
2251 indicate this.
2253 Numeric Replies:
2255 ERR_NOSUCHSERVER ERR_FILEERROR
2256 RPL_USERSSTART RPL_USERS
2257 RPL_NOUSERS RPL_ENDOFUSERS
2258 ERR_USERSDISABLED
2260 Disabled Reply:
2262 ERR_USERSDISABLED
2264 Examples:
2266 USERS eff.org ; request a list of users logged in on
2267 server eff.org
2269 :John USERS tolsun.oulu.fi ; request from John for a list of users
2270 logged in on server tolsun.oulu.fi
2272 5.6 Operwall message
2274 Command: WALLOPS
2275 Parameters: Text to be sent to all operators currently online
2277 Sends a message to all operators currently online. After
2278 implementing WALLOPS as a user command it was found that it was
2279 often and commonly abused as a means of sending a message to a lot
2280 of people (much similar to WALL). Due to this it is recommended
2281 that the current implementation of WALLOPS be used as an
2282 example by allowing and recognising only servers as the senders of
2283 WALLOPS.
2285 Numeric Replies:
2287 ERR_NEEDMOREPARAMS
2289 Examples:
2291 :csd.bu.edu WALLOPS :Connect '*.uiuc.edu 6667' from Joshua; WALLOPS
2292 message from csd.bu.edu announcing a
2293 CONNECT message it received and acted
2294 upon from Joshua.
2298 Oikarinen & Reed [Page 41]
2299 \f
2300 RFC 1459 Internet Relay Chat Protocol May 1993
2303 5.7 Userhost message
2305 Command: USERHOST
2306 Parameters: <nickname>{<space><nickname>}
2308 The USERHOST command takes a list of up to 5 nicknames, each
2309 separated by a space character and returns a list of information
2310 about each nickname that it found. The returned list has each reply
2311 separated by a space.
2313 Numeric Replies:
2315 RPL_USERHOST ERR_NEEDMOREPARAMS
2317 Examples:
2319 USERHOST Wiz Michael Marty p ;USERHOST request for information on
2320 nicks "Wiz", "Michael", "Marty" and "p"
2322 5.8 Ison message
2324 Command: ISON
2325 Parameters: <nickname>{<space><nickname>}
2327 The ISON command was implemented to provide a quick and efficient
2328 means to get a response about whether a given nickname was currently
2329 on IRC. ISON only takes one (1) parameter: a space-separated list of
2330 nicks. For each nickname in the list that is present, the server
2331 adds that to its reply string. Thus the reply string may return
2332 empty (none of the given nicks are present), an exact copy of the
2333 parameter string (all of them present) or as any other subset of the
2334 set of nicks given in the parameter. The only limit on the number
2335 of nicks that may be checked is that the combined length must not be
2336 too large as to cause the server to chop it off so it fits in 512
2337 characters.
2339 ISON is only be processed by the server local to the client sending
2340 the command and thus not passed onto other servers for further
2341 processing.
2343 Numeric Replies:
2345 RPL_ISON ERR_NEEDMOREPARAMS
2347 Examples:
2349 ISON phone trillian WiZ jarlek Avalon Angel Monstah
2350 ; Sample ISON request for 7 nicks.
2354 Oikarinen & Reed [Page 42]
2355 \f
2356 RFC 1459 Internet Relay Chat Protocol May 1993
2359 6. REPLIES
2361 The following is a list of numeric replies which are generated in
2362 response to the commands given above. Each numeric is given with its
2363 number, name and reply string.
2365 6.1 Error Replies.
2367 401 ERR_NOSUCHNICK
2368 "<nickname> :No such nick/channel"
2370 - Used to indicate the nickname parameter supplied to a
2371 command is currently unused.
2373 402 ERR_NOSUCHSERVER
2374 "<server name> :No such server"
2376 - Used to indicate the server name given currently
2377 doesn't exist.
2379 403 ERR_NOSUCHCHANNEL
2380 "<channel name> :No such channel"
2382 - Used to indicate the given channel name is invalid.
2384 404 ERR_CANNOTSENDTOCHAN
2385 "<channel name> :Cannot send to channel"
2387 - Sent to a user who is either (a) not on a channel
2388 which is mode +n or (b) not a chanop (or mode +v) on
2389 a channel which has mode +m set and is trying to send
2390 a PRIVMSG message to that channel.
2392 405 ERR_TOOMANYCHANNELS
2393 "<channel name> :You have joined too many \
2394 channels"
2395 - Sent to a user when they have joined the maximum
2396 number of allowed channels and they try to join
2397 another channel.
2399 406 ERR_WASNOSUCHNICK
2400 "<nickname> :There was no such nickname"
2402 - Returned by WHOWAS to indicate there is no history
2403 information for that nickname.
2405 407 ERR_TOOMANYTARGETS
2406 "<target> :Duplicate recipients. No message \
2410 Oikarinen & Reed [Page 43]
2411 \f
2412 RFC 1459 Internet Relay Chat Protocol May 1993
2415 delivered"
2417 - Returned to a client which is attempting to send a
2418 PRIVMSG/NOTICE using the user@host destination format
2419 and for a user@host which has several occurrences.
2421 409 ERR_NOORIGIN
2422 ":No origin specified"
2424 - PING or PONG message missing the originator parameter
2425 which is required since these commands must work
2426 without valid prefixes.
2428 411 ERR_NORECIPIENT
2429 ":No recipient given (<command>)"
2430 412 ERR_NOTEXTTOSEND
2431 ":No text to send"
2432 413 ERR_NOTOPLEVEL
2433 "<mask> :No toplevel domain specified"
2434 414 ERR_WILDTOPLEVEL
2435 "<mask> :Wildcard in toplevel domain"
2437 - 412 - 414 are returned by PRIVMSG to indicate that
2438 the message wasn't delivered for some reason.
2439 ERR_NOTOPLEVEL and ERR_WILDTOPLEVEL are errors that
2440 are returned when an invalid use of
2441 "PRIVMSG $<server>" or "PRIVMSG #<host>" is attempted.
2443 421 ERR_UNKNOWNCOMMAND
2444 "<command> :Unknown command"
2446 - Returned to a registered client to indicate that the
2447 command sent is unknown by the server.
2449 422 ERR_NOMOTD
2450 ":MOTD File is missing"
2452 - Server's MOTD file could not be opened by the server.
2454 423 ERR_NOADMININFO
2455 "<server> :No administrative info available"
2457 - Returned by a server in response to an ADMIN message
2458 when there is an error in finding the appropriate
2459 information.
2461 424 ERR_FILEERROR
2462 ":File error doing <file op> on <file>"
2466 Oikarinen & Reed [Page 44]
2467 \f
2468 RFC 1459 Internet Relay Chat Protocol May 1993
2471 - Generic error message used to report a failed file
2472 operation during the processing of a message.
2474 431 ERR_NONICKNAMEGIVEN
2475 ":No nickname given"
2477 - Returned when a nickname parameter expected for a
2478 command and isn't found.
2480 432 ERR_ERRONEUSNICKNAME
2481 "<nick> :Erroneus nickname"
2483 - Returned after receiving a NICK message which contains
2484 characters which do not fall in the defined set. See
2485 section x.x.x for details on valid nicknames.
2487 433 ERR_NICKNAMEINUSE
2488 "<nick> :Nickname is already in use"
2490 - Returned when a NICK message is processed that results
2491 in an attempt to change to a currently existing
2492 nickname.
2494 436 ERR_NICKCOLLISION
2495 "<nick> :Nickname collision KILL"
2497 - Returned by a server to a client when it detects a
2498 nickname collision (registered of a NICK that
2499 already exists by another server).
2501 441 ERR_USERNOTINCHANNEL
2502 "<nick> <channel> :They aren't on that channel"
2504 - Returned by the server to indicate that the target
2505 user of the command is not on the given channel.
2507 442 ERR_NOTONCHANNEL
2508 "<channel> :You're not on that channel"
2510 - Returned by the server whenever a client tries to
2511 perform a channel effecting command for which the
2512 client isn't a member.
2514 443 ERR_USERONCHANNEL
2515 "<user> <channel> :is already on channel"
2517 - Returned when a client tries to invite a user to a
2518 channel they are already on.
2522 Oikarinen & Reed [Page 45]
2523 \f
2524 RFC 1459 Internet Relay Chat Protocol May 1993
2527 444 ERR_NOLOGIN
2528 "<user> :User not logged in"
2530 - Returned by the summon after a SUMMON command for a
2531 user was unable to be performed since they were not
2532 logged in.
2534 445 ERR_SUMMONDISABLED
2535 ":SUMMON has been disabled"
2537 - Returned as a response to the SUMMON command. Must be
2538 returned by any server which does not implement it.
2540 446 ERR_USERSDISABLED
2541 ":USERS has been disabled"
2543 - Returned as a response to the USERS command. Must be
2544 returned by any server which does not implement it.
2546 451 ERR_NOTREGISTERED
2547 ":You have not registered"
2549 - Returned by the server to indicate that the client
2550 must be registered before the server will allow it
2551 to be parsed in detail.
2553 461 ERR_NEEDMOREPARAMS
2554 "<command> :Not enough parameters"
2556 - Returned by the server by numerous commands to
2557 indicate to the client that it didn't supply enough
2558 parameters.
2560 462 ERR_ALREADYREGISTRED
2561 ":You may not reregister"
2563 - Returned by the server to any link which tries to
2564 change part of the registered details (such as
2565 password or user details from second USER message).
2568 463 ERR_NOPERMFORHOST
2569 ":Your host isn't among the privileged"
2571 - Returned to a client which attempts to register with
2572 a server which does not been setup to allow
2573 connections from the host the attempted connection
2574 is tried.
2578 Oikarinen & Reed [Page 46]
2579 \f
2580 RFC 1459 Internet Relay Chat Protocol May 1993
2583 464 ERR_PASSWDMISMATCH
2584 ":Password incorrect"
2586 - Returned to indicate a failed attempt at registering
2587 a connection for which a password was required and
2588 was either not given or incorrect.
2590 465 ERR_YOUREBANNEDCREEP
2591 ":You are banned from this server"
2593 - Returned after an attempt to connect and register
2594 yourself with a server which has been setup to
2595 explicitly deny connections to you.
2597 467 ERR_KEYSET
2598 "<channel> :Channel key already set"
2599 471 ERR_CHANNELISFULL
2600 "<channel> :Cannot join channel (+l)"
2601 472 ERR_UNKNOWNMODE
2602 "<char> :is unknown mode char to me"
2603 473 ERR_INVITEONLYCHAN
2604 "<channel> :Cannot join channel (+i)"
2605 474 ERR_BANNEDFROMCHAN
2606 "<channel> :Cannot join channel (+b)"
2607 475 ERR_BADCHANNELKEY
2608 "<channel> :Cannot join channel (+k)"
2609 481 ERR_NOPRIVILEGES
2610 ":Permission Denied- You're not an IRC operator"
2612 - Any command requiring operator privileges to operate
2613 must return this error to indicate the attempt was
2614 unsuccessful.
2616 482 ERR_CHANOPRIVSNEEDED
2617 "<channel> :You're not channel operator"
2619 - Any command requiring 'chanop' privileges (such as
2620 MODE messages) must return this error if the client
2621 making the attempt is not a chanop on the specified
2622 channel.
2624 483 ERR_CANTKILLSERVER
2625 ":You cant kill a server!"
2627 - Any attempts to use the KILL command on a server
2628 are to be refused and this error returned directly
2629 to the client.
2634 Oikarinen & Reed [Page 47]
2635 \f
2636 RFC 1459 Internet Relay Chat Protocol May 1993
2639 491 ERR_NOOPERHOST
2640 ":No O-lines for your host"
2642 - If a client sends an OPER message and the server has
2643 not been configured to allow connections from the
2644 client's host as an operator, this error must be
2645 returned.
2647 501 ERR_UMODEUNKNOWNFLAG
2648 ":Unknown MODE flag"
2650 - Returned by the server to indicate that a MODE
2651 message was sent with a nickname parameter and that
2652 the a mode flag sent was not recognized.
2654 502 ERR_USERSDONTMATCH
2655 ":Cant change mode for other users"
2657 - Error sent to any user trying to view or change the
2658 user mode for a user other than themselves.
2660 6.2 Command responses.
2662 300 RPL_NONE
2663 Dummy reply number. Not used.
2665 302 RPL_USERHOST
2666 ":[<reply>{<space><reply>}]"
2668 - Reply format used by USERHOST to list replies to
2669 the query list. The reply string is composed as
2670 follows:
2672 <reply> ::= <nick>['*'] '=' <'+'|'-'><hostname>
2674 The '*' indicates whether the client has registered
2675 as an Operator. The '-' or '+' characters represent
2676 whether the client has set an AWAY message or not
2677 respectively.
2679 303 RPL_ISON
2680 ":[<nick> {<space><nick>}]"
2682 - Reply format used by ISON to list replies to the
2683 query list.
2685 301 RPL_AWAY
2686 "<nick> :<away message>"
2690 Oikarinen & Reed [Page 48]
2691 \f
2692 RFC 1459 Internet Relay Chat Protocol May 1993
2695 305 RPL_UNAWAY
2696 ":You are no longer marked as being away"
2697 306 RPL_NOWAWAY
2698 ":You have been marked as being away"
2700 - These replies are used with the AWAY command (if
2701 allowed). RPL_AWAY is sent to any client sending a
2702 PRIVMSG to a client which is away. RPL_AWAY is only
2703 sent by the server to which the client is connected.
2704 Replies RPL_UNAWAY and RPL_NOWAWAY are sent when the
2705 client removes and sets an AWAY message.
2707 311 RPL_WHOISUSER
2708 "<nick> <user> <host> * :<real name>"
2709 312 RPL_WHOISSERVER
2710 "<nick> <server> :<server info>"
2711 313 RPL_WHOISOPERATOR
2712 "<nick> :is an IRC operator"
2713 317 RPL_WHOISIDLE
2714 "<nick> <integer> :seconds idle"
2715 318 RPL_ENDOFWHOIS
2716 "<nick> :End of /WHOIS list"
2717 319 RPL_WHOISCHANNELS
2718 "<nick> :{[@|+]<channel><space>}"
2720 - Replies 311 - 313, 317 - 319 are all replies
2721 generated in response to a WHOIS message. Given that
2722 there are enough parameters present, the answering
2723 server must either formulate a reply out of the above
2724 numerics (if the query nick is found) or return an
2725 error reply. The '*' in RPL_WHOISUSER is there as
2726 the literal character and not as a wild card. For
2727 each reply set, only RPL_WHOISCHANNELS may appear
2728 more than once (for long lists of channel names).
2729 The '@' and '+' characters next to the channel name
2730 indicate whether a client is a channel operator or
2731 has been granted permission to speak on a moderated
2732 channel. The RPL_ENDOFWHOIS reply is used to mark
2733 the end of processing a WHOIS message.
2735 314 RPL_WHOWASUSER
2736 "<nick> <user> <host> * :<real name>"
2737 369 RPL_ENDOFWHOWAS
2738 "<nick> :End of WHOWAS"
2740 - When replying to a WHOWAS message, a server must use
2741 the replies RPL_WHOWASUSER, RPL_WHOISSERVER or
2742 ERR_WASNOSUCHNICK for each nickname in the presented
2746 Oikarinen & Reed [Page 49]
2747 \f
2748 RFC 1459 Internet Relay Chat Protocol May 1993
2751 list. At the end of all reply batches, there must
2752 be RPL_ENDOFWHOWAS (even if there was only one reply
2753 and it was an error).
2755 321 RPL_LISTSTART
2756 "Channel :Users Name"
2757 322 RPL_LIST
2758 "<channel> <# visible> :<topic>"
2759 323 RPL_LISTEND
2760 ":End of /LIST"
2762 - Replies RPL_LISTSTART, RPL_LIST, RPL_LISTEND mark
2763 the start, actual replies with data and end of the
2764 server's response to a LIST command. If there are
2765 no channels available to return, only the start
2766 and end reply must be sent.
2768 324 RPL_CHANNELMODEIS
2769 "<channel> <mode> <mode params>"
2771 331 RPL_NOTOPIC
2772 "<channel> :No topic is set"
2773 332 RPL_TOPIC
2774 "<channel> :<topic>"
2776 - When sending a TOPIC message to determine the
2777 channel topic, one of two replies is sent. If
2778 the topic is set, RPL_TOPIC is sent back else
2779 RPL_NOTOPIC.
2781 341 RPL_INVITING
2782 "<channel> <nick>"
2784 - Returned by the server to indicate that the
2785 attempted INVITE message was successful and is
2786 being passed onto the end client.
2788 342 RPL_SUMMONING
2789 "<user> :Summoning user to IRC"
2791 - Returned by a server answering a SUMMON message to
2792 indicate that it is summoning that user.
2794 351 RPL_VERSION
2795 "<version>.<debuglevel> <server> :<comments>"
2797 - Reply by the server showing its version details.
2798 The <version> is the version of the software being
2802 Oikarinen & Reed [Page 50]
2803 \f
2804 RFC 1459 Internet Relay Chat Protocol May 1993
2807 used (including any patchlevel revisions) and the
2808 <debuglevel> is used to indicate if the server is
2809 running in "debug mode".
2811 The "comments" field may contain any comments about
2812 the version or further version details.
2814 352 RPL_WHOREPLY
2815 "<channel> <user> <host> <server> <nick> \
2816 <H|G>[*][@|+] :<hopcount> <real name>"
2817 315 RPL_ENDOFWHO
2818 "<name> :End of /WHO list"
2820 - The RPL_WHOREPLY and RPL_ENDOFWHO pair are used
2821 to answer a WHO message. The RPL_WHOREPLY is only
2822 sent if there is an appropriate match to the WHO
2823 query. If there is a list of parameters supplied
2824 with a WHO message, a RPL_ENDOFWHO must be sent
2825 after processing each list item with <name> being
2826 the item.
2828 353 RPL_NAMREPLY
2829 "<channel> :[[@|+]<nick> [[@|+]<nick> [...]]]"
2830 366 RPL_ENDOFNAMES
2831 "<channel> :End of /NAMES list"
2833 - To reply to a NAMES message, a reply pair consisting
2834 of RPL_NAMREPLY and RPL_ENDOFNAMES is sent by the
2835 server back to the client. If there is no channel
2836 found as in the query, then only RPL_ENDOFNAMES is
2837 returned. The exception to this is when a NAMES
2838 message is sent with no parameters and all visible
2839 channels and contents are sent back in a series of
2840 RPL_NAMEREPLY messages with a RPL_ENDOFNAMES to mark
2841 the end.
2843 364 RPL_LINKS
2844 "<mask> <server> :<hopcount> <server info>"
2845 365 RPL_ENDOFLINKS
2846 "<mask> :End of /LINKS list"
2848 - In replying to the LINKS message, a server must send
2849 replies back using the RPL_LINKS numeric and mark the
2850 end of the list using an RPL_ENDOFLINKS reply.
2852 367 RPL_BANLIST
2853 "<channel> <banid>"
2854 368 RPL_ENDOFBANLIST
2858 Oikarinen & Reed [Page 51]
2859 \f
2860 RFC 1459 Internet Relay Chat Protocol May 1993
2863 "<channel> :End of channel ban list"
2865 - When listing the active 'bans' for a given channel,
2866 a server is required to send the list back using the
2867 RPL_BANLIST and RPL_ENDOFBANLIST messages. A separate
2868 RPL_BANLIST is sent for each active banid. After the
2869 banids have been listed (or if none present) a
2870 RPL_ENDOFBANLIST must be sent.
2872 371 RPL_INFO
2873 ":<string>"
2874 374 RPL_ENDOFINFO
2875 ":End of /INFO list"
2877 - A server responding to an INFO message is required to
2878 send all its 'info' in a series of RPL_INFO messages
2879 with a RPL_ENDOFINFO reply to indicate the end of the
2880 replies.
2882 375 RPL_MOTDSTART
2883 ":- <server> Message of the day - "
2884 372 RPL_MOTD
2885 ":- <text>"
2886 376 RPL_ENDOFMOTD
2887 ":End of /MOTD command"
2889 - When responding to the MOTD message and the MOTD file
2890 is found, the file is displayed line by line, with
2891 each line no longer than 80 characters, using
2892 RPL_MOTD format replies. These should be surrounded
2893 by a RPL_MOTDSTART (before the RPL_MOTDs) and an
2894 RPL_ENDOFMOTD (after).
2896 381 RPL_YOUREOPER
2897 ":You are now an IRC operator"
2899 - RPL_YOUREOPER is sent back to a client which has
2900 just successfully issued an OPER message and gained
2901 operator status.
2903 382 RPL_REHASHING
2904 "<config file> :Rehashing"
2906 - If the REHASH option is used and an operator sends
2907 a REHASH message, an RPL_REHASHING is sent back to
2908 the operator.
2910 391 RPL_TIME
2914 Oikarinen & Reed [Page 52]
2915 \f
2916 RFC 1459 Internet Relay Chat Protocol May 1993
2919 "<server> :<string showing server's local time>"
2921 - When replying to the TIME message, a server must send
2922 the reply using the RPL_TIME format above. The string
2923 showing the time need only contain the correct day and
2924 time there. There is no further requirement for the
2925 time string.
2927 392 RPL_USERSSTART
2928 ":UserID Terminal Host"
2929 393 RPL_USERS
2930 ":%-8s %-9s %-8s"
2931 394 RPL_ENDOFUSERS
2932 ":End of users"
2933 395 RPL_NOUSERS
2934 ":Nobody logged in"
2936 - If the USERS message is handled by a server, the
2937 replies RPL_USERSTART, RPL_USERS, RPL_ENDOFUSERS and
2938 RPL_NOUSERS are used. RPL_USERSSTART must be sent
2939 first, following by either a sequence of RPL_USERS
2940 or a single RPL_NOUSER. Following this is
2941 RPL_ENDOFUSERS.
2943 200 RPL_TRACELINK
2944 "Link <version & debug level> <destination> \
2945 <next server>"
2946 201 RPL_TRACECONNECTING
2947 "Try. <class> <server>"
2948 202 RPL_TRACEHANDSHAKE
2949 "H.S. <class> <server>"
2950 203 RPL_TRACEUNKNOWN
2951 "???? <class> [<client IP address in dot form>]"
2952 204 RPL_TRACEOPERATOR
2953 "Oper <class> <nick>"
2954 205 RPL_TRACEUSER
2955 "User <class> <nick>"
2956 206 RPL_TRACESERVER
2957 "Serv <class> <int>S <int>C <server> \
2958 <nick!user|*!*>@<host|server>"
2959 208 RPL_TRACENEWTYPE
2960 "<newtype> 0 <client name>"
2961 261 RPL_TRACELOG
2962 "File <logfile> <debug level>"
2964 - The RPL_TRACE* are all returned by the server in
2965 response to the TRACE message. How many are
2966 returned is dependent on the the TRACE message and
2970 Oikarinen & Reed [Page 53]
2971 \f
2972 RFC 1459 Internet Relay Chat Protocol May 1993
2975 whether it was sent by an operator or not. There
2976 is no predefined order for which occurs first.
2977 Replies RPL_TRACEUNKNOWN, RPL_TRACECONNECTING and
2978 RPL_TRACEHANDSHAKE are all used for connections
2979 which have not been fully established and are either
2980 unknown, still attempting to connect or in the
2981 process of completing the 'server handshake'.
2982 RPL_TRACELINK is sent by any server which handles
2983 a TRACE message and has to pass it on to another
2984 server. The list of RPL_TRACELINKs sent in
2985 response to a TRACE command traversing the IRC
2986 network should reflect the actual connectivity of
2987 the servers themselves along that path.
2988 RPL_TRACENEWTYPE is to be used for any connection
2989 which does not fit in the other categories but is
2990 being displayed anyway.
2992 211 RPL_STATSLINKINFO
2993 "<linkname> <sendq> <sent messages> \
2994 <sent bytes> <received messages> \
2995 <received bytes> <time open>"
2996 212 RPL_STATSCOMMANDS
2997 "<command> <count>"
2998 213 RPL_STATSCLINE
2999 "C <host> * <name> <port> <class>"
3000 214 RPL_STATSNLINE
3001 "N <host> * <name> <port> <class>"
3002 215 RPL_STATSILINE
3003 "I <host> * <host> <port> <class>"
3004 216 RPL_STATSKLINE
3005 "K <host> * <username> <port> <class>"
3006 218 RPL_STATSYLINE
3007 "Y <class> <ping frequency> <connect \
3008 frequency> <max sendq>"
3009 219 RPL_ENDOFSTATS
3010 "<stats letter> :End of /STATS report"
3011 241 RPL_STATSLLINE
3012 "L <hostmask> * <servername> <maxdepth>"
3013 242 RPL_STATSUPTIME
3014 ":Server Up %d days %d:%02d:%02d"
3015 243 RPL_STATSOLINE
3016 "O <hostmask> * <name>"
3017 244 RPL_STATSHLINE
3018 "H <hostmask> * <servername>"
3020 221 RPL_UMODEIS
3021 "<user mode string>"
3026 Oikarinen & Reed [Page 54]
3027 \f
3028 RFC 1459 Internet Relay Chat Protocol May 1993
3031 - To answer a query about a client's own mode,
3032 RPL_UMODEIS is sent back.
3034 251 RPL_LUSERCLIENT
3035 ":There are <integer> users and <integer> \
3036 invisible on <integer> servers"
3037 252 RPL_LUSEROP
3038 "<integer> :operator(s) online"
3039 253 RPL_LUSERUNKNOWN
3040 "<integer> :unknown connection(s)"
3041 254 RPL_LUSERCHANNELS
3042 "<integer> :channels formed"
3043 255 RPL_LUSERME
3044 ":I have <integer> clients and <integer> \
3045 servers"
3047 - In processing an LUSERS message, the server
3048 sends a set of replies from RPL_LUSERCLIENT,
3049 RPL_LUSEROP, RPL_USERUNKNOWN,
3050 RPL_LUSERCHANNELS and RPL_LUSERME. When
3051 replying, a server must send back
3052 RPL_LUSERCLIENT and RPL_LUSERME. The other
3053 replies are only sent back if a non-zero count
3054 is found for them.
3056 256 RPL_ADMINME
3057 "<server> :Administrative info"
3058 257 RPL_ADMINLOC1
3059 ":<admin info>"
3060 258 RPL_ADMINLOC2
3061 ":<admin info>"
3062 259 RPL_ADMINEMAIL
3063 ":<admin info>"
3065 - When replying to an ADMIN message, a server
3066 is expected to use replies RLP_ADMINME
3067 through to RPL_ADMINEMAIL and provide a text
3068 message with each. For RPL_ADMINLOC1 a
3069 description of what city, state and country
3070 the server is in is expected, followed by
3071 details of the university and department
3072 (RPL_ADMINLOC2) and finally the administrative
3073 contact for the server (an email address here
3074 is required) in RPL_ADMINEMAIL.
3082 Oikarinen & Reed [Page 55]
3083 \f
3084 RFC 1459 Internet Relay Chat Protocol May 1993
3087 6.3 Reserved numerics.
3089 These numerics are not described above since they fall into one of
3090 the following categories:
3092 1. no longer in use;
3094 2. reserved for future planned use;
3096 3. in current use but are part of a non-generic 'feature' of
3097 the current IRC server.
3099 209 RPL_TRACECLASS 217 RPL_STATSQLINE
3100 231 RPL_SERVICEINFO 232 RPL_ENDOFSERVICES
3101 233 RPL_SERVICE 234 RPL_SERVLIST
3102 235 RPL_SERVLISTEND
3103 316 RPL_WHOISCHANOP 361 RPL_KILLDONE
3104 362 RPL_CLOSING 363 RPL_CLOSEEND
3105 373 RPL_INFOSTART 384 RPL_MYPORTIS
3106 466 ERR_YOUWILLBEBANNED 476 ERR_BADCHANMASK
3107 492 ERR_NOSERVICEHOST
3109 7. Client and server authentication
3111 Clients and servers are both subject to the same level of
3112 authentication. For both, an IP number to hostname lookup (and
3113 reverse check on this) is performed for all connections made to the
3114 server. Both connections are then subject to a password check (if
3115 there is a password set for that connection). These checks are
3116 possible on all connections although the password check is only
3117 commonly used with servers.
3119 An additional check that is becoming of more and more common is that
3120 of the username responsible for making the connection. Finding the
3121 username of the other end of the connection typically involves
3122 connecting to an authentication server such as IDENT as described in
3123 RFC 1413.
3125 Given that without passwords it is not easy to reliably determine who
3126 is on the other end of a network connection, use of passwords is
3127 strongly recommended on inter-server connections in addition to any
3128 other measures such as using an ident server.
3130 8. Current implementations
3132 The only current implementation of this protocol is the IRC server,
3133 version 2.8. Earlier versions may implement some or all of the
3134 commands described by this document with NOTICE messages replacing
3138 Oikarinen & Reed [Page 56]
3139 \f
3140 RFC 1459 Internet Relay Chat Protocol May 1993
3143 many of the numeric replies. Unfortunately, due to backward
3144 compatibility requirements, the implementation of some parts of this
3145 document varies with what is laid out. On notable difference is:
3147 * recognition that any LF or CR anywhere in a message marks the
3148 end of that message (instead of requiring CR-LF);
3150 The rest of this section deals with issues that are mostly of
3151 importance to those who wish to implement a server but some parts
3152 also apply directly to clients as well.
3154 8.1 Network protocol: TCP - why it is best used here.
3156 IRC has been implemented on top of TCP since TCP supplies a reliable
3157 network protocol which is well suited to this scale of conferencing.
3158 The use of multicast IP is an alternative, but it is not widely
3159 available or supported at the present time.
3161 8.1.1 Support of Unix sockets
3163 Given that Unix domain sockets allow listen/connect operations, the
3164 current implementation can be configured to listen and accept both
3165 client and server connections on a Unix domain socket. These are
3166 recognized as sockets where the hostname starts with a '/'.
3168 When providing any information about the connections on a Unix domain
3169 socket, the server is required to supplant the actual hostname in
3170 place of the pathname unless the actual socket name is being asked
3171 for.
3173 8.2 Command Parsing
3175 To provide useful 'non-buffered' network IO for clients and servers,
3176 each connection is given its own private 'input buffer' in which the
3177 results of the most recent read and parsing are kept. A buffer size
3178 of 512 bytes is used so as to hold 1 full message, although, this
3179 will usually hold several commands. The private buffer is parsed
3180 after every read operation for valid messages. When dealing with
3181 multiple messages from one client in the buffer, care should be taken
3182 in case one happens to cause the client to be 'removed'.
3184 8.3 Message delivery
3186 It is common to find network links saturated or hosts to which you
3187 are sending data unable to send data. Although Unix typically
3188 handles this through the TCP window and internal buffers, the server
3189 often has large amounts of data to send (especially when a new
3190 server-server link forms) and the small buffers provided in the
3194 Oikarinen & Reed [Page 57]
3195 \f
3196 RFC 1459 Internet Relay Chat Protocol May 1993
3199 kernel are not enough for the outgoing queue. To alleviate this
3200 problem, a "send queue" is used as a FIFO queue for data to be sent.
3201 A typical "send queue" may grow to 200 Kbytes on a large IRC network
3202 with a slow network connection when a new server connects.
3204 When polling its connections, a server will first read and parse all
3205 incoming data, queuing any data to be sent out. When all available
3206 input is processed, the queued data is sent. This reduces the number
3207 of write() system calls and helps TCP make bigger packets.
3209 8.4 Connection 'Liveness'
3211 To detect when a connection has died or become unresponsive, the
3212 server must ping each of its connections that it doesn't get a
3213 response from in a given amount of time.
3215 If a connection doesn't respond in time, its connection is closed
3216 using the appropriate procedures. A connection is also dropped if
3217 its sendq grows beyond the maximum allowed, because it is better to
3218 close a slow connection than have a server process block.
3220 8.5 Establishing a server to client connection
3222 Upon connecting to an IRC server, a client is sent the MOTD (if
3223 present) as well as the current user/server count (as per the LUSER
3224 command). The server is also required to give an unambiguous message
3225 to the client which states its name and version as well as any other
3226 introductory messages which may be deemed appropriate.
3228 After dealing with this, the server must then send out the new user's
3229 nickname and other information as supplied by itself (USER command)
3230 and as the server could discover (from DNS/authentication servers).
3231 The server must send this information out with NICK first followed by
3232 USER.
3234 8.6 Establishing a server-server connection.
3236 The process of establishing of a server-to-server connection is
3237 fraught with danger since there are many possible areas where
3238 problems can occur - the least of which are race conditions.
3240 After a server has received a connection following by a PASS/SERVER
3241 pair which were recognised as being valid, the server should then
3242 reply with its own PASS/SERVER information for that connection as
3243 well as all of the other state information it knows about as
3244 described below.
3246 When the initiating server receives a PASS/SERVER pair, it too then
3250 Oikarinen & Reed [Page 58]
3251 \f
3252 RFC 1459 Internet Relay Chat Protocol May 1993
3255 checks that the server responding is authenticated properly before
3256 accepting the connection to be that server.
3258 8.6.1 Server exchange of state information when connecting
3260 The order of state information being exchanged between servers is
3261 essential. The required order is as follows:
3263 * all known other servers;
3265 * all known user information;
3267 * all known channel information.
3269 Information regarding servers is sent via extra SERVER messages, user
3270 information with NICK/USER/MODE/JOIN messages and channels with MODE
3271 messages.
3273 NOTE: channel topics are *NOT* exchanged here because the TOPIC
3274 command overwrites any old topic information, so at best, the two
3275 sides of the connection would exchange topics.
3277 By passing the state information about servers first, any collisions
3278 with servers that already exist occur before nickname collisions due
3279 to a second server introducing a particular nickname. Due to the IRC
3280 network only being able to exist as an acyclic graph, it may be
3281 possible that the network has already reconnected in another
3282 location, the place where the collision occurs indicating where the
3283 net needs to split.
3285 8.7 Terminating server-client connections
3287 When a client connection closes, a QUIT message is generated on
3288 behalf of the client by the server to which the client connected. No
3289 other message is to be generated or used.
3291 8.8 Terminating server-server connections
3293 If a server-server connection is closed, either via a remotely
3294 generated SQUIT or 'natural' causes, the rest of the connected IRC
3295 network must have its information updated with by the server which
3296 detected the closure. The server then sends a list of SQUITs (one
3297 for each server behind that connection) and a list of QUITs (again,
3298 one for each client behind that connection).
3306 Oikarinen & Reed [Page 59]
3307 \f
3308 RFC 1459 Internet Relay Chat Protocol May 1993
3311 8.9 Tracking nickname changes
3313 All IRC servers are required to keep a history of recent nickname
3314 changes. This is required to allow the server to have a chance of
3315 keeping in touch of things when nick-change race conditions occur
3316 with commands which manipulate them. Commands which must trace nick
3317 changes are:
3319 * KILL (the nick being killed)
3321 * MODE (+/- o,v)
3323 * KICK (the nick being kicked)
3325 No other commands are to have nick changes checked for.
3327 In the above cases, the server is required to first check for the
3328 existence of the nickname, then check its history to see who that
3329 nick currently belongs to (if anyone!). This reduces the chances of
3330 race conditions but they can still occur with the server ending up
3331 affecting the wrong client. When performing a change trace for an
3332 above command it is recommended that a time range be given and
3333 entries which are too old ignored.
3335 For a reasonable history, a server should be able to keep previous
3336 nickname for every client it knows about if they all decided to
3337 change. This size is limited by other factors (such as memory, etc).
3339 8.10 Flood control of clients
3341 With a large network of interconnected IRC servers, it is quite easy
3342 for any single client attached to the network to supply a continuous
3343 stream of messages that result in not only flooding the network, but
3344 also degrading the level of service provided to others. Rather than
3345 require every 'victim' to be provide their own protection, flood
3346 protection was written into the server and is applied to all clients
3347 except services. The current algorithm is as follows:
3349 * check to see if client's `message timer' is less than
3350 current time (set to be equal if it is);
3352 * read any data present from the client;
3354 * while the timer is less than ten seconds ahead of the current
3355 time, parse any present messages and penalize the client by
3356 2 seconds for each message;
3358 which in essence means that the client may send 1 message every 2
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3364 RFC 1459 Internet Relay Chat Protocol May 1993
3367 seconds without being adversely affected.
3369 8.11 Non-blocking lookups
3371 In a real-time environment, it is essential that a server process do
3372 as little waiting as possible so that all the clients are serviced
3373 fairly. Obviously this requires non-blocking IO on all network
3374 read/write operations. For normal server connections, this was not
3375 difficult, but there are other support operations that may cause the
3376 server to block (such as disk reads). Where possible, such activity
3377 should be performed with a short timeout.
3379 8.11.1 Hostname (DNS) lookups
3381 Using the standard resolver libraries from Berkeley and others has
3382 meant large delays in some cases where replies have timed out. To
3383 avoid this, a separate set of DNS routines were written which were
3384 setup for non-blocking IO operations and then polled from within the
3385 main server IO loop.
3387 8.11.2 Username (Ident) lookups
3389 Although there are numerous ident libraries for use and inclusion
3390 into other programs, these caused problems since they operated in a
3391 synchronous manner and resulted in frequent delays. Again the
3392 solution was to write a set of routines which would cooperate with
3393 the rest of the server and work using non-blocking IO.
3395 8.12 Configuration File
3397 To provide a flexible way of setting up and running the server, it is
3398 recommended that a configuration file be used which contains
3399 instructions to the server on the following:
3401 * which hosts to accept client connections from;
3403 * which hosts to allow to connect as servers;
3405 * which hosts to connect to (both actively and
3406 passively);
3408 * information about where the server is (university,
3409 city/state, company are examples of this);
3411 * who is responsible for the server and an email address
3412 at which they can be contacted;
3414 * hostnames and passwords for clients which wish to be given
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3420 RFC 1459 Internet Relay Chat Protocol May 1993
3423 access to restricted operator commands.
3425 In specifying hostnames, both domain names and use of the 'dot'
3426 notation (127.0.0.1) should both be accepted. It must be possible to
3427 specify the password to be used/accepted for all outgoing and
3428 incoming connections (although the only outgoing connections are
3429 those to other servers).
3431 The above list is the minimum requirement for any server which wishes
3432 to make a connection with another server. Other items which may be
3433 of use are:
3435 * specifying which servers other server may introduce;
3437 * how deep a server branch is allowed to become;
3439 * hours during which clients may connect.
3441 8.12.1 Allowing clients to connect
3443 A server should use some sort of 'access control list' (either in the
3444 configuration file or elsewhere) that is read at startup and used to
3445 decide what hosts clients may use to connect to it.
3447 Both 'deny' and 'allow' should be implemented to provide the required
3448 flexibility for host access control.
3450 8.12.2 Operators
3452 The granting of operator privileges to a disruptive person can have
3453 dire consequences for the well-being of the IRC net in general due to
3454 the powers given to them. Thus, the acquisition of such powers
3455 should not be very easy. The current setup requires two 'passwords'
3456 to be used although one of them is usually easy guessed. Storage of
3457 oper passwords in configuration files is preferable to hard coding
3458 them in and should be stored in a crypted format (ie using crypt(3)
3459 from Unix) to prevent easy theft.
3461 8.12.3 Allowing servers to connect
3463 The interconnection of server is not a trivial matter: a bad
3464 connection can have a large impact on the usefulness of IRC. Thus,
3465 each server should have a list of servers to which it may connect and
3466 which servers may connect to it. Under no circumstances should a
3467 server allow an arbitrary host to connect as a server. In addition
3468 to which servers may and may not connect, the configuration file
3469 should also store the password and other characteristics of that
3470 link.
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3476 RFC 1459 Internet Relay Chat Protocol May 1993
3479 8.12.4 Administrivia
3481 To provide accurate and valid replies to the ADMIN command (see
3482 section 4.3.7), the server should find the relevant details in the
3483 configuration.
3485 8.13 Channel membership
3487 The current server allows any registered local user to join upto 10
3488 different channels. There is no limit imposed on non-local users so
3489 that the server remains (reasonably) consistant with all others on a
3490 channel membership basis
3492 9. Current problems
3494 There are a number of recognized problems with this protocol, all of
3495 which hope to be solved sometime in the near future during its
3496 rewrite. Currently, work is underway to find working solutions to
3497 these problems.
3499 9.1 Scalability
3501 It is widely recognized that this protocol does not scale
3502 sufficiently well when used in a large arena. The main problem comes
3503 from the requirement that all servers know about all other servers
3504 and users and that information regarding them be updated as soon as
3505 it changes. It is also desirable to keep the number of servers low
3506 so that the path length between any two points is kept minimal and
3507 the spanning tree as strongly branched as possible.
3509 9.2 Labels
3511 The current IRC protocol has 3 types of labels: the nickname, the
3512 channel name and the server name. Each of the three types has its
3513 own domain and no duplicates are allowed inside that domain.
3514 Currently, it is possible for users to pick the label for any of the
3515 three, resulting in collisions. It is widely recognized that this
3516 needs reworking, with a plan for unique names for channels and nicks
3517 that don't collide being desirable as well as a solution allowing a
3518 cyclic tree.
3520 9.2.1 Nicknames
3522 The idea of the nickname on IRC is very convenient for users to use
3523 when talking to each other outside of a channel, but there is only a
3524 finite nickname space and being what they are, its not uncommon for
3525 several people to want to use the same nick. If a nickname is chosen
3526 by two people using this protocol, either one will not succeed or
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3532 RFC 1459 Internet Relay Chat Protocol May 1993
3535 both will removed by use of KILL (4.6.1).
3537 9.2.2 Channels
3539 The current channel layout requires that all servers know about all
3540 channels, their inhabitants and properties. Besides not scaling
3541 well, the issue of privacy is also a concern. A collision of
3542 channels is treated as an inclusive event (both people who create the
3543 new channel are considered to be members of it) rather than an
3544 exclusive one such as used to solve nickname collisions.
3546 9.2.3 Servers
3548 Although the number of servers is usually small relative to the
3549 number of users and channels, they two currently required to be known
3550 globally, either each one separately or hidden behind a mask.
3552 9.3 Algorithms
3554 In some places within the server code, it has not been possible to
3555 avoid N^2 algorithms such as checking the channel list of a set
3556 of clients.
3558 In current server versions, there are no database consistency checks,
3559 each server assumes that a neighbouring server is correct. This
3560 opens the door to large problems if a connecting server is buggy or
3561 otherwise tries to introduce contradictions to the existing net.
3563 Currently, because of the lack of unique internal and global labels,
3564 there are a multitude of race conditions that exist. These race
3565 conditions generally arise from the problem of it taking time for
3566 messages to traverse and effect the IRC network. Even by changing to
3567 unique labels, there are problems with channel-related commands being
3568 disrupted.
3570 10. Current support and availability
3572 Mailing lists for IRC related discussion:
3573 Future protocol: ircd-three-request@eff.org
3574 General discussion: operlist-request@eff.org
3576 Software implemenations
3577 cs.bu.edu:/irc
3578 nic.funet.fi:/pub/irc
3579 coombs.anu.edu.au:/pub/irc
3581 Newsgroup: alt.irc
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3588 RFC 1459 Internet Relay Chat Protocol May 1993
3591 Security Considerations
3593 Security issues are discussed in sections 4.1, 4.1.1, 4.1.3, 5.5, and
3594 7.
3596 12. Authors' Addresses
3598 Jarkko Oikarinen
3599 Tuirantie 17 as 9
3600 90500 OULU
3601 FINLAND
3603 Email: jto@tolsun.oulu.fi
3606 Darren Reed
3607 4 Pateman Street
3608 Watsonia, Victoria 3087
3609 Australia
3611 Email: avalon@coombs.anu.edu.au
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