RFC 1459

Network Working Group                                      J. Oikarinen

Request for Comments: 1459                                      D. Reed

                                                               May 1993



                      Internet Relay Chat Protocol


Status of This Memo


   This memo defines an Experimental Protocol for the Internet

   community.  Discussion and suggestions for improvement are requested.

   Please refer to the current edition of the "IAB Official Protocol

   Standards" for the standardization state and status of this protocol.

   Distribution of this memo is unlimited.


Abstract


   The IRC protocol was developed over the last 4 years since it was

   first implemented as a means for users on a BBS to chat amongst

   themselves.  Now it supports a world-wide network of servers and

   clients, and is stringing to cope with growth. Over the past 2 years,

   the average number of users connected to the main IRC network has

   grown by a factor of 10.


   The IRC protocol is a text-based protocol, with the simplest client

   being any socket program capable of connecting to the server.


Table of Contents


   1.  INTRODUCTION ...............................................    4

      1.1  Servers ................................................    4

      1.2  Clients ................................................    5

         1.2.1 Operators ..........................................    5

      1.3 Channels ................................................    5

      1.3.1  Channel Operators ....................................    6

   2. THE IRC SPECIFICATION .......................................    7

      2.1 Overview ................................................    7

      2.2 Character codes .........................................    7

      2.3 Messages ................................................    7

         2.3.1  Message format in 'pseudo' BNF ....................    8

      2.4 Numeric replies .........................................   10

   3. IRC Concepts ................................................   10

      3.1 One-to-one communication ................................   10

      3.2 One-to-many .............................................   11

         3.2.1 To a list ..........................................   11

         3.2.2 To a group (channel) ...............................   11

         3.2.3 To a host/server mask ..............................   12

      3.3 One to all ..............................................   12




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         3.3.1 Client to Client ...................................   12

         3.3.2 Clients to Server ..................................   12

         3.3.3 Server to Server ...................................   12

   4. MESSAGE DETAILS .............................................   13

      4.1 Connection Registration .................................   13

         4.1.1 Password message ...................................   14

         4.1.2 Nickname message ...................................   14

         4.1.3 User message .......................................   15

         4.1.4 Server message .....................................   16

         4.1.5 Operator message ...................................   17

         4.1.6 Quit message .......................................   17

         4.1.7 Server Quit message ................................   18

      4.2 Channel operations ......................................   19

         4.2.1 Join message .......................................   19

         4.2.2 Part message .......................................   20

         4.2.3 Mode message .......................................   21

            4.2.3.1 Channel modes .................................   21

            4.2.3.2 User modes ....................................   22

         4.2.4 Topic message ......................................   23

         4.2.5 Names message ......................................   24

         4.2.6 List message .......................................   24

         4.2.7 Invite message .....................................   25

         4.2.8 Kick message .......................................   25

      4.3 Server queries and commands .............................   26

         4.3.1 Version message ....................................   26

         4.3.2 Stats message ......................................   27

         4.3.3 Links message ......................................   28

         4.3.4 Time message .......................................   29

         4.3.5 Connect message ....................................   29

         4.3.6 Trace message ......................................   30

         4.3.7 Admin message ......................................   31

         4.3.8 Info message .......................................   31

      4.4 Sending messages ........................................   32

         4.4.1 Private messages ...................................   32

         4.4.2 Notice messages ....................................   33

      4.5 User-based queries ......................................   33

         4.5.1 Who query ..........................................   33

         4.5.2 Whois query ........................................   34

         4.5.3 Whowas message .....................................   35

      4.6 Miscellaneous messages ..................................   35

         4.6.1 Kill message .......................................   36

         4.6.2 Ping message .......................................   37

         4.6.3 Pong message .......................................   37

         4.6.4 Error message ......................................   38

   5. OPTIONAL MESSAGES ...........................................   38

      5.1 Away message ............................................   38

      5.2 Rehash command ..........................................   39

      5.3 Restart command .........................................   39




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      5.4 Summon message ..........................................   40

      5.5 Users message ...........................................   40

      5.6 Operwall command ........................................   41

      5.7 Userhost message ........................................   42

      5.8 Ison message ............................................   42

   6. REPLIES .....................................................   43

      6.1 Error Replies ...........................................   43

      6.2 Command responses .......................................   48

      6.3 Reserved numerics .......................................   56

   7. Client and server authentication ............................   56

   8. Current Implementations Details .............................   56

      8.1 Network protocol: TCP ...................................   57

         8.1.1 Support of Unix sockets ............................   57

      8.2 Command Parsing .........................................   57

      8.3 Message delivery ........................................   57

      8.4 Connection 'Liveness' ...................................   58

      8.5 Establishing a server-client connection .................   58

      8.6 Establishing a server-server connection .................   58

         8.6.1 State information exchange when connecting .........   59

      8.7 Terminating server-client connections ...................   59

      8.8 Terminating server-server connections ...................   59

      8.9 Tracking nickname changes ...............................   60

      8.10 Flood control of clients ...............................   60

      8.11 Non-blocking lookups ...................................   61

         8.11.1 Hostname (DNS) lookups ............................   61

         8.11.2 Username (Ident) lookups ..........................   61

      8.12 Configuration file .....................................   61

         8.12.1 Allowing clients to connect .......................   62

         8.12.2 Operators .........................................   62

         8.12.3 Allowing servers to connect .......................   62

         8.12.4 Administrivia .....................................   63

      8.13 Channel membership .....................................   63

   9. Current problems ............................................   63

      9.1 Scalability .............................................   63

      9.2 Labels ..................................................   63

         9.2.1 Nicknames ..........................................   63

         9.2.2 Channels ...........................................   64

         9.2.3 Servers ............................................   64

      9.3 Algorithms ..............................................   64

   10. Support and availability ...................................   64

   11. Security Considerations ....................................   65

   12. Authors' Addresses .........................................   65










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1.  INTRODUCTION


   The IRC (Internet Relay Chat) protocol has been designed over a

   number of years for use with text based conferencing.  This document

   describes the current IRC protocol.


   The IRC protocol has been developed on systems using the TCP/IP

   network protocol, although there is no requirement that this remain

   the only sphere in which it operates.


   IRC itself is a teleconferencing system, which (through the use of

   the client-server model) is well-suited to running on many machines

   in a distributed fashion.  A typical setup involves a single process

   (the server) forming a central point for clients (or other servers)

   to connect to, performing the required message delivery/multiplexing

   and other functions.


1.1 Servers


   The server forms the backbone of IRC, providing a point to which

   clients may connect to to talk to each other, and a point for other

   servers to connect to, forming an IRC network.  The only network

   configuration allowed for IRC servers is that of a spanning tree [see

   Fig. 1] where each server acts as a central node for the rest of the

   net it sees.



                           [ Server 15 ]  [ Server 13 ] [ Server 14]

                                 /                \         /

                                /                  \       /

        [ Server 11 ] ------ [ Server 1 ]       [ Server 12]

                              /        \          /

                             /          \        /

                  [ Server 2 ]          [ Server 3 ]

                    /       \                      \

                   /         \                      \

           [ Server 4 ]    [ Server 5 ]         [ Server 6 ]

            /    |    \                           /

           /     |     \                         /

          /      |      \____                   /

         /       |           \                 /

 [ Server 7 ] [ Server 8 ] [ Server 9 ]   [ Server 10 ]


                                  :

                               [ etc. ]

                                  :


                 [ Fig. 1. Format of IRC server network ]




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1.2 Clients


   A client is anything connecting to a server that is not another

   server.  Each client is distinguished from other clients by a unique

   nickname having a maximum length of nine (9) characters.  See the

   protocol grammar rules for what may and may not be used in a

   nickname.  In addition to the nickname, all servers must have the

   following information about all clients: the real name of the host

   that the client is running on, the username of the client on that

   host, and the server to which the client is connected.


1.2.1 Operators


   To allow a reasonable amount of order to be kept within the IRC

   network, a special class of clients (operators) is allowed to perform

   general maintenance functions on the network.  Although the powers

   granted to an operator can be considered as 'dangerous', they are

   nonetheless required.  Operators should be able to perform basic

   network tasks such as disconnecting and reconnecting servers as

   needed to prevent long-term use of bad network routing.  In

   recognition of this need, the protocol discussed herein provides for

   operators only to be able to perform such functions.  See sections

   4.1.7 (SQUIT) and 4.3.5 (CONNECT).


   A more controversial power of operators is the ability  to  remove  a

   user  from  the connected network by 'force', i.e. operators are able

   to close the connection between any client and server.   The

   justification for  this  is delicate since its abuse is both

   destructive and annoying.  For further details on this type of

   action, see section 4.6.1 (KILL).


1.3 Channels


   A channel is a named group of one or more clients which will all

   receive messages addressed to that channel.  The channel is created

   implicitly when the first client joins it, and the channel ceases to

   exist when the last client leaves it.  While channel exists, any

   client can reference the channel using the name of the channel.


   Channels names are strings (beginning with a '&' or '#' character) of

   length up to 200 characters.  Apart from the the requirement that the

   first character being either '&' or '#'; the only restriction on a

   channel name is that it may not contain any spaces (' '), a control G

   (^G or ASCII 7), or a comma (',' which is used as a list item

   separator by the protocol).


   There are two types of channels allowed by this protocol.  One is a

   distributed channel which is known to all the servers that are




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   connected to the network. These channels are marked by the first

   character being a only clients on the server where it exists may join

   it.  These are distinguished by a leading '&' character.  On top of

   these two types, there are the various channel modes available to

   alter the characteristics of individual channels.  See section 4.2.3

   (MODE command) for more details on this.


   To create a new channel or become part of an existing channel, a user

   is required to JOIN the channel.  If the channel doesn't exist prior

   to joining, the channel is created and the creating user becomes a

   channel operator.  If the channel already exists, whether or not your

   request to JOIN that channel is honoured depends on the current modes

   of the channel. For example, if the channel is invite-only, (+i),

   then you may only join if invited.  As part of the protocol, a user

   may be a part of several channels at once, but a limit of ten (10)

   channels is recommended as being ample for both experienced and

   novice users.  See section 8.13 for more information on this.


   If the IRC network becomes disjoint because of a split between two

   servers, the channel on each side is only composed of those clients

   which are connected to servers on the respective sides of the split,

   possibly ceasing to exist on one side of the split.  When the split

   is healed, the connecting servers announce to each other who they

   think is in each channel and the mode of that channel.  If the

   channel exists on both sides, the JOINs and MODEs are interpreted in

   an inclusive manner so that both sides of the new connection will

   agree about which clients are in the channel and what modes the

   channel has.


1.3.1 Channel Operators


   The channel operator (also referred to as a "chop" or "chanop") on a

   given channel is considered to 'own' that channel.  In recognition of

   this status, channel operators are endowed with certain powers which

   enable them to keep control and some sort of sanity in their channel.

   As an owner of a channel, a channel operator is not required to have

   reasons for their actions, although if their actions are generally

   antisocial or otherwise abusive, it might be reasonable to ask an IRC

   operator to intervene, or for the usersjust leave and go elsewhere

   and form their own channel.


   The commands which may only be used by channel operators are:


        KICK    - Eject a client from the channel

        MODE    - Change the channel's mode

        INVITE  - Invite a client to an invite-only channel (mode +i)

        TOPIC   - Change the channel topic in a mode +t channel





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   A channel operator is identified by the '@' symbol next to their

   nickname whenever it is associated with a channel (ie replies to the

   NAMES, WHO and WHOIS commands).


2. The IRC Specification


2.1 Overview


   The protocol as described herein is for use both with server to

   server and client to server connections.  There are, however, more

   restrictions on client connections (which are considered to be

   untrustworthy) than on server connections.


2.2 Character codes


   No specific character set is specified. The protocol is based on a a

   set of codes which are composed of eight (8) bits, making up an

   octet.  Each message may be composed of any number of these octets;

   however, some octet values are used for control codes which act as

   message delimiters.


   Regardless of being an 8-bit protocol, the delimiters and keywords

   are such that protocol is mostly usable from USASCII terminal and a

   telnet connection.


   Because of IRC's scandanavian origin, the characters {}| are

   considered to be the lower case equivalents of the characters []\,

   respectively. This is a critical issue when determining the

   equivalence of two nicknames.


2.3 Messages


   Servers and clients send eachother messages which may or may not

   generate a reply.  If the message contains a valid command, as

   described in later sections, the client should expect a reply as

   specified but it is not advised to wait forever for the reply; client

   to server and server to server communication is essentially

   asynchronous in nature.


   Each IRC message may consist of up to three main parts: the prefix

   (optional), the command, and the command parameters (of which there

   may be up to 15).  The prefix, command, and all parameters are

   separated by one (or more) ASCII space character(s) (0x20).


   The presence of a prefix is indicated with a single leading ASCII

   colon character (':', 0x3b), which must be the first character of the

   message itself.  There must be no gap (whitespace) between the colon

   and the prefix.  The prefix is used by servers to indicate the true




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   origin of the message.  If the prefix is missing from the message, it

   is assumed to have originated from the connection from which it was

   received.  Clients should not use prefix when sending a message from

   themselves; if they use a prefix, the only valid prefix is the

   registered nickname associated with the client.  If the source

   identified by the prefix cannot be found from the server's internal

   database, or if the source is registered from a different link than

   from which the message arrived, the server must ignore the message

   silently.


   The command must either be a valid IRC command or a three (3) digit

   number represented in ASCII text.


   IRC messages are always lines of characters terminated with a CR-LF

   (Carriage Return - Line Feed) pair, and these messages shall not

   exceed 512 characters in length, counting all characters including

   the trailing CR-LF. Thus, there are 510 characters maximum allowed

   for the command and its parameters.  There is no provision for

   continuation message lines.  See section 7 for more details about

   current implementations.


2.3.1 Message format in 'pseudo' BNF


   The protocol messages must be extracted from the contiguous stream of

   octets.  The current solution is to designate two characters, CR and

   LF, as message separators.   Empty  messages  are  silently  ignored,

   which permits  use  of  the  sequence  CR-LF  between  messages

   without extra problems.


   The extracted message is parsed into the components <prefix>,

   <command> and list of parameters matched either by <middle> or

   <trailing> components.


   The BNF representation for this is:



<message>  ::= [':' <prefix> <SPACE> ] <command> <params> <crlf>

<prefix>   ::= <servername> | <nick> [ '!' <user> ] [ '@' <host> ]

<command>  ::= <letter> { <letter> } | <number> <number> <number>

<SPACE>    ::= ' ' { ' ' }

<params>   ::= <SPACE> [ ':' <trailing> | <middle> <params> ]


<middle>   ::= <Any *non-empty* sequence of octets not including SPACE

               or NUL or CR or LF, the first of which may not be ':'>

<trailing> ::= <Any, possibly *empty*, sequence of octets not including

                 NUL or CR or LF>


<crlf>     ::= CR LF




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NOTES:


  1)    <SPACE> is consists only of SPACE character(s) (0x20).

        Specially notice that TABULATION, and all other control

        characters are considered NON-WHITE-SPACE.


  2)    After extracting the parameter list, all parameters are equal,

        whether matched by <middle> or <trailing>. <Trailing> is just

        a syntactic trick to allow SPACE within parameter.


  3)    The fact that CR and LF cannot appear in parameter strings is

        just artifact of the message framing. This might change later.


  4)    The NUL character is not special in message framing, and

        basically could end up inside a parameter, but as it would

        cause extra complexities in normal C string handling. Therefore

        NUL is not allowed within messages.


  5)    The last parameter may be an empty string.


  6)    Use of the extended prefix (['!' <user> ] ['@' <host> ]) must

        not be used in server to server communications and is only

        intended for server to client messages in order to provide

        clients with more useful information about who a message is

        from without the need for additional queries.


   Most protocol messages specify additional semantics and syntax for

   the extracted parameter strings dictated by their position in the

   list.  For example, many server commands will assume that the first

   parameter after the command is the list of targets, which can be

   described with:


   <target>     ::= <to> [ "," <target> ]

   <to>         ::= <channel> | <user> '@' <servername> | <nick> | <mask>

   <channel>    ::= ('#' | '&') <chstring>

   <servername> ::= <host>

   <host>       ::= see RFC 952 [DNS:4] for details on allowed hostnames

   <nick>       ::= <letter> { <letter> | <number> | <special> }

   <mask>       ::= ('#' | '$') <chstring>

   <chstring>   ::= <any 8bit code except SPACE, BELL, NUL, CR, LF and

                     comma (',')>


   Other parameter syntaxes are:


   <user>       ::= <nonwhite> { <nonwhite> }

   <letter>     ::= 'a' ... 'z' | 'A' ... 'Z'

   <number>     ::= '0' ... '9'

   <special>    ::= '-' | '[' | ']' | '\' | '`' | '^' | '{' | '}'




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   <nonwhite>   ::= <any 8bit code except SPACE (0x20), NUL (0x0), CR

                     (0xd), and LF (0xa)>


2.4 Numeric replies


   Most of the messages sent to the server generate a reply of some

   sort.  The most common reply is the numeric reply, used for both

   errors and normal replies.  The numeric reply must be sent as one

   message consisting of the sender prefix, the three digit numeric, and

   the target of the reply.  A numeric reply is not allowed to originate

   from a client; any such messages received by a server are silently

   dropped. In all other respects, a numeric reply is just like a normal

   message, except that the keyword is made up of 3 numeric digits

   rather than a string of letters.  A list of different replies is

   supplied in section 6.


3. IRC Concepts.


   This section is devoted to describing the actual concepts behind  the

   organization  of  the  IRC  protocol and how the current

   implementations deliver different classes of messages.




                          1--\

                              A        D---4

                          2--/ \      /

                                B----C

                               /      \

                              3        E


   Servers: A, B, C, D, E         Clients: 1, 2, 3, 4


                    [ Fig. 2. Sample small IRC network ]


3.1 One-to-one communication


   Communication on a one-to-one basis is usually only performed by

   clients, since most server-server traffic is not a result of servers

   talking only to each other.  To provide a secure means for clients to

   talk to each other, it is required that all servers be able to send a

   message in exactly one direction along the spanning tree in order to

   reach any client.  The path of a message being delivered is the

   shortest path between any two points on the spanning tree.


   The following examples all refer to Figure 2 above.






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Example 1:

     A message between clients 1 and 2 is only seen by server A, which

     sends it straight to client 2.


Example 2:

     A message between clients 1 and 3 is seen by servers A & B, and

     client 3.  No other clients or servers are allowed see the message.


Example 3:

     A message between clients 2 and 4 is seen by servers A, B, C & D

     and client 4 only.


3.2 One-to-many


   The main goal of IRC is to provide a  forum  which  allows  easy  and

   efficient  conferencing (one to many conversations).  IRC offers

   several means to achieve this, each serving its own purpose.


3.2.1 To a list


   The least efficient style of one-to-many conversation is through

   clients talking to a 'list' of users.  How this is done is almost

   self explanatory: the client gives a list of destinations to which

   the message is to be delivered and the server breaks it up and

   dispatches a separate copy of the message to each given destination.

   This isn't as efficient as using a group since the destination list

   is broken up and the dispatch sent without checking to make sure

   duplicates aren't sent down each path.


3.2.2 To a group (channel)


   In IRC the channel has a role equivalent to that of the multicast

   group; their existence is dynamic (coming and going as people join

   and leave channels) and the actual conversation carried out on a

   channel is only sent to servers which are supporting users on a given

   channel.  If there are multiple users on a server in the same

   channel, the message text is sent only once to that server and then

   sent to each client on the channel.  This action is then repeated for

   each client-server combination until the original message has fanned

   out and reached each member of the channel.


   The following examples all refer to Figure 2.


Example 4:

     Any channel with 1 client in it. Messages to the channel go to the

     server and then nowhere else.






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Example 5:

     2 clients in a channel. All messages traverse a path as if they

     were private messages between the two clients outside a channel.


Example 6:

     Clients 1, 2 and 3 in a channel.  All messages to the channel are

     sent to all clients and only those servers which must be traversed

     by the message if it were a private message to a single client.  If

     client 1 sends a message, it goes back to client 2 and then via

     server B to client 3.


3.2.3 To a host/server mask


   To provide IRC operators with some mechanism to send  messages  to  a

   large body of related users, host and server mask messages are

   provided.  These messages are sent to users whose host or server

   information  match that  of  the mask.  The messages are only sent to

   locations where users are, in a fashion similar to that of channels.


3.3 One-to-all


   The one-to-all type of message is better described as a broadcast

   message, sent to all clients or servers or both.  On a large network

   of users and servers, a single message can result in a lot of traffic

   being sent over the network in an effort to reach all of the desired

   destinations.


   For some messages, there is no option but to broadcast it to all

   servers so that the state information held by each server is

   reasonably consistent between servers.


3.3.1 Client-to-Client


   There is no class of message which, from a single message, results in

   a message being sent to every other client.


3.3.2 Client-to-Server


   Most of the commands which result in a change of state information

   (such as channel membership, channel mode, user status, etc) must be

   sent to all servers by default, and this distribution may not be

   changed by the client.


3.3.3 Server-to-Server.


   While most messages between servers are distributed to all 'other'

   servers, this is only required for any message that affects either a

   user, channel or server.  Since these are the basic items found in




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   IRC, nearly all messages originating from a server are broadcast to

   all other connected servers.


4. Message details


   On the following pages are descriptions of each message recognized by

   the IRC server and client.  All commands described in this section

   must be implemented by any server for this protocol.


   Where the reply ERR_NOSUCHSERVER is listed, it means that the

   <server> parameter could not be found.  The server must not send any

   other replies after this for that command.


   The server to which a client is connected is required to parse the

   complete message, returning any appropriate errors.  If the server

   encounters a fatal error while parsing a message, an error must be

   sent back to the client and the parsing terminated.  A fatal error

   may be considered to be incorrect command, a destination which is

   otherwise unknown to the server (server, nick or channel names fit

   this category), not enough parameters or incorrect privileges.


   If a full set of parameters is presented, then each must be checked

   for validity and appropriate responses sent back to the client.  In

   the case of messages which use parameter lists using the comma as an

   item separator, a reply must be sent for each item.


   In the examples below, some messages appear using the full format:


   :Name COMMAND parameter list


   Such examples represent a message from "Name" in transit between

   servers, where it is essential to include the name of the original

   sender of the message so remote servers may send back a reply along

   the correct path.


4.1 Connection Registration


   The commands described here are used to register a connection with an

   IRC server as either a user or a server as well as correctly

   disconnect.


   A "PASS" command is not required for either client or server

   connection to be registered, but it must precede the server message

   or the latter of the NICK/USER combination.  It is strongly

   recommended that all server connections have a password in order to

   give some level of security to the actual connections.  The

   recommended order for a client to register is as follows:





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           1. Pass message

           2. Nick message

           3. User message


4.1.1 Password message



      Command: PASS

   Parameters: <password>


   The PASS command is used to set a 'connection password'.  The

   password can and must be set before any attempt to register the

   connection is made.  Currently this requires that clients send a PASS

   command before sending the NICK/USER combination and servers *must*

   send a PASS command before any SERVER command.  The password supplied

   must match the one contained in the C/N lines (for servers) or I

   lines (for clients).  It is possible to send multiple PASS commands

   before registering but only the last one sent is used for

   verification and it may not be changed once registered.  Numeric

   Replies:


           ERR_NEEDMOREPARAMS              ERR_ALREADYREGISTRED


   Example:


           PASS secretpasswordhere


4.1.2 Nick message


      Command: NICK

   Parameters: <nickname> [ <hopcount> ]


   NICK message is used to give user a nickname or change the previous

   one.  The <hopcount> parameter is only used by servers to indicate

   how far away a nick is from its home server.  A local connection has

   a hopcount of 0.  If supplied by a client, it must be ignored.


   If a NICK message arrives at a server which already knows about an

   identical nickname for another client, a nickname collision occurs.

   As a result of a nickname collision, all instances of the nickname

   are removed from the server's database, and a KILL command is issued

   to remove the nickname from all other server's database. If the NICK

   message causing the collision was a nickname change, then the

   original (old) nick must be removed as well.


   If the server recieves an identical NICK from a client which is

   directly connected, it may issue an ERR_NICKCOLLISION to the local

   client, drop the NICK command, and not generate any kills.




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   Numeric Replies:


           ERR_NONICKNAMEGIVEN             ERR_ERRONEUSNICKNAME

           ERR_NICKNAMEINUSE               ERR_NICKCOLLISION


   Example:


   NICK Wiz                        ; Introducing new nick "Wiz".


   :WiZ NICK Kilroy                ; WiZ changed his nickname to Kilroy.


4.1.3 User message


      Command: USER

   Parameters: <username> <hostname> <servername> <realname>


   The USER message is used at the beginning of connection to specify

   the username, hostname, servername and realname of s new user.  It is

   also used in communication between servers to indicate new user

   arriving on IRC, since only after both USER and NICK have been

   received from a client does a user become registered.


   Between servers USER must to be prefixed with client's NICKname.

   Note that hostname and servername are normally ignored by the IRC

   server when the USER command comes from a directly connected client

   (for security reasons), but they are used in server to server

   communication.  This means that a NICK must always be sent to a

   remote server when a new user is being introduced to the rest of the

   network before the accompanying USER is sent.


   It must be noted that realname parameter must be the last parameter,

   because it may contain space characters and must be prefixed with a

   colon (':') to make sure this is recognised as such.


   Since it is easy for a client to lie about its username by relying

   solely on the USER message, the use of an "Identity Server" is

   recommended.  If the host which a user connects from has such a

   server enabled the username is set to that as in the reply from the

   "Identity Server".


   Numeric Replies:


           ERR_NEEDMOREPARAMS              ERR_ALREADYREGISTRED


   Examples:



   USER guest tolmoon tolsun :Ronnie Reagan




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                                   ; User registering themselves with a

                                   username of "guest" and real name

                                   "Ronnie Reagan".



   :testnick USER guest tolmoon tolsun :Ronnie Reagan

                                   ; message between servers with the

                                   nickname for which the USER command

                                   belongs to


4.1.4 Server message


      Command: SERVER

   Parameters: <servername> <hopcount> <info>


   The server message is used to tell a server that the other end of a

   new connection is a server. This message is also used to pass server

   data over whole net.  When a new server is connected to net,

   information about it be broadcast to the whole network.  <hopcount>

   is used to give all servers some internal information on how far away

   all servers are.  With a full server list, it would be possible to

   construct a map of the entire server tree, but hostmasks prevent this

   from being done.


   The SERVER message must only be accepted from either (a) a connection

   which is yet to be registered and is attempting to register as a

   server, or (b) an existing connection to another server, in  which

   case the SERVER message is introducing a new server behind that

   server.


   Most errors that occur with the receipt of a SERVER command result in

   the connection being terminated by the destination host (target

   SERVER).  Error replies are usually sent using the "ERROR" command

   rather than the numeric since the ERROR command has several useful

   properties which make it useful here.


   If a SERVER message is parsed and attempts to introduce a server

   which is already known to the receiving server, the connection from

   which that message must be closed (following the correct procedures),

   since a duplicate route to a server has formed and the acyclic nature

   of the IRC tree broken.


   Numeric Replies:


           ERR_ALREADYREGISTRED


   Example:





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SERVER test.oulu.fi 1 :[tolsun.oulu.fi] Experimental server

                                ; New server test.oulu.fi introducing

                                itself and attempting to register.  The

                                name in []'s is the hostname for the

                                host running test.oulu.fi.



:tolsun.oulu.fi SERVER csd.bu.edu 5 :BU Central Server

                                ; Server tolsun.oulu.fi is our uplink

                                for csd.bu.edu which is 5 hops away.


4.1.5 Oper


      Command: OPER

   Parameters: <user> <password>


   OPER message is used by a normal user to obtain operator privileges.

   The combination of <user> and <password> are required to gain

   Operator privileges.


   If the client sending the OPER command supplies the correct password

   for the given user, the server then informs the rest of the network

   of the new operator by issuing a "MODE +o" for the clients nickname.


   The OPER message is client-server only.


   Numeric Replies:


           ERR_NEEDMOREPARAMS              RPL_YOUREOPER

           ERR_NOOPERHOST                  ERR_PASSWDMISMATCH


   Example:


   OPER foo bar                    ; Attempt to register as an operator

                                   using a username of "foo" and "bar" as

                                   the password.


4.1.6 Quit


      Command: QUIT

   Parameters: [<Quit message>]


   A client session is ended with a quit message.  The server must close

   the connection to a client which sends a QUIT message. If a "Quit

   Message" is given, this will be sent instead of the default message,

   the nickname.


   When netsplits (disconnecting of two servers) occur, the quit message




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   is composed of the names of two servers involved, separated by a

   space.  The first name is that of the server which is still connected

   and the second name is that of the server that has become

   disconnected.


   If, for some other reason, a client connection is closed without  the

   client  issuing  a  QUIT  command  (e.g.  client  dies and EOF occurs

   on socket), the server is required to fill in the quit  message  with

   some sort  of  message  reflecting the nature of the event which

   caused it to happen.


   Numeric Replies:


           None.


   Examples:


   QUIT :Gone to have lunch        ; Preferred message format.


4.1.7 Server quit message


      Command: SQUIT

   Parameters: <server> <comment>


   The SQUIT message is needed to tell about quitting or dead servers.

   If a server wishes to break the connection to another server it must

   send a SQUIT message to the other server, using the the name of the

   other server as the server parameter, which then closes its

   connection to the quitting server.


   This command is also available operators to help keep a network of

   IRC servers connected in an orderly fashion.  Operators may also

   issue an SQUIT message for a remote server connection.  In this case,

   the SQUIT must be parsed by each server inbetween the operator and

   the remote server, updating the view of the network held by each

   server as explained below.


   The <comment> should be supplied by all operators who execute a SQUIT

   for a remote server (that is not connected to the server they are

   currently on) so that other operators are aware for the reason of

   this action.  The <comment> is also filled in by servers which may

   place an error or similar message here.


   Both of the servers which are on either side of the connection being

   closed are required to to send out a SQUIT message (to all its other

   server connections) for all other servers which are considered to be

   behind that link.





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   Similarly, a QUIT message must be sent to the other connected servers

   rest of the network on behalf of all clients behind that link.  In

   addition to this, all channel members of a channel which lost a

   member due to the split must be sent a QUIT message.


   If a server connection is terminated prematurely (e.g. the server  on

   the  other  end  of  the  link  died),  the  server  which  detects

   this disconnection is required to inform the rest of  the  network

   that  the connection  has  closed  and  fill  in  the comment field

   with something appropriate.


   Numeric replies:


           ERR_NOPRIVILEGES                ERR_NOSUCHSERVER


   Example:


   SQUIT tolsun.oulu.fi :Bad Link ? ; the server link tolson.oulu.fi has

                                   been terminated because of "Bad Link".


   :Trillian SQUIT cm22.eng.umd.edu :Server out of control

                                    ; message from Trillian to disconnect

                                   "cm22.eng.umd.edu" from the net

                                    because "Server out of control".


4.2 Channel operations


   This group of messages is concerned with manipulating channels, their

   properties (channel modes), and their contents (typically clients).

   In implementing these, a number of race conditions are inevitable

   when clients at opposing ends of a network send commands which will

   ultimately clash.  It is also required that servers keep a nickname

   history to ensure that wherever a <nick> parameter is given, the

   server check its history in case it has recently been changed.


4.2.1 Join message


      Command: JOIN

   Parameters: <channel>{,<channel>} [<key>{,<key>}]


   The JOIN command is used by client to start listening a specific

   channel. Whether or not a client is allowed to join a channel is

   checked only by the server the client is connected to; all other

   servers automatically add the user to the channel when it is received

   from other servers.  The conditions which affect this are as follows:


           1.  the user must be invited if the channel is invite-only;





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           2.  the user's nick/username/hostname must not match any

               active bans;


           3.  the correct key (password) must be given if it is set.


   These are discussed in more detail under the MODE command (see

   section 4.2.3 for more details).


   Once a user has joined a channel, they receive notice about all

   commands their server receives which affect the channel.  This

   includes MODE, KICK, PART, QUIT and of course PRIVMSG/NOTICE.  The

   JOIN command needs to be broadcast to all servers so that each server

   knows where to find the users who are on the channel.  This allows

   optimal delivery of PRIVMSG/NOTICE messages to the channel.


   If a JOIN is successful, the user is then sent the channel's topic

   (using RPL_TOPIC) and the list of users who are on the channel (using

   RPL_NAMREPLY), which must include the user joining.


   Numeric Replies:


           ERR_NEEDMOREPARAMS              ERR_BANNEDFROMCHAN

           ERR_INVITEONLYCHAN              ERR_BADCHANNELKEY

           ERR_CHANNELISFULL               ERR_BADCHANMASK

           ERR_NOSUCHCHANNEL               ERR_TOOMANYCHANNELS

           RPL_TOPIC


   Examples:


   JOIN #foobar                    ; join channel #foobar.


   JOIN &foo fubar                 ; join channel &foo using key "fubar".


   JOIN #foo,&bar fubar            ; join channel #foo using key "fubar"

                                   and &bar using no key.


   JOIN #foo,#bar fubar,foobar     ; join channel #foo using key "fubar".

                                   and channel #bar using key "foobar".


   JOIN #foo,#bar                  ; join channels #foo and #bar.


   :WiZ JOIN #Twilight_zone        ; JOIN message from WiZ


4.2.2 Part message


      Command: PART

   Parameters: <channel>{,<channel>}





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   The PART message causes the client sending the message to be removed

   from the list of active users for all given channels listed in the

   parameter string.


   Numeric Replies:


           ERR_NEEDMOREPARAMS              ERR_NOSUCHCHANNEL

           ERR_NOTONCHANNEL


   Examples:


   PART #twilight_zone             ; leave channel "#twilight_zone"


   PART #oz-ops,&group5            ; leave both channels "&group5" and

                                   "#oz-ops".


4.2.3 Mode message


      Command: MODE


   The MODE command is a dual-purpose command in IRC.  It allows both

   usernames and channels to have their mode changed.  The rationale for

   this choice is that one day nicknames will be obsolete and the

   equivalent property will be the channel.


   When parsing MODE messages, it is recommended that the entire message

   be parsed first and then the changes which resulted then passed on.


4.2.3.1 Channel modes


   Parameters: <channel> {[+|-]|o|p|s|i|t|n|b|v} [<limit>] [<user>]

               [<ban mask>]


   The MODE command is provided so that channel operators may change the

   characteristics of `their' channel.  It is also required that servers

   be able to change channel modes so that channel operators may be

   created.


   The various modes available for channels are as follows:


           o - give/take channel operator privileges;

           p - private channel flag;

           s - secret channel flag;

           i - invite-only channel flag;

           t - topic settable by channel operator only flag;

           n - no messages to channel from clients on the outside;

           m - moderated channel;

           l - set the user limit to channel;




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           b - set a ban mask to keep users out;

           v - give/take the ability to speak on a moderated channel;

           k - set a channel key (password).


   When using the 'o' and 'b' options, a restriction on a total of three

   per mode command has been imposed.  That is, any combination of 'o'

   and


4.2.3.2 User modes


   Parameters: <nickname> {[+|-]|i|w|s|o}


   The user MODEs are typically changes which affect either how the

   client is seen by others or what 'extra' messages the client is sent.

   A user MODE command may only be accepted if both the sender of the

   message and the nickname given as a parameter are both the same.


   The available modes are as follows:


           i - marks a users as invisible;

           s - marks a user for receipt of server notices;

           w - user receives wallops;

           o - operator flag.


   Additional modes may be available later on.


   If a user attempts to make themselves an operator using the "+o"

   flag, the attempt should be ignored.  There is no restriction,

   however, on anyone `deopping' themselves (using "-o").  Numeric

   Replies:


           ERR_NEEDMOREPARAMS              RPL_CHANNELMODEIS

           ERR_CHANOPRIVSNEEDED            ERR_NOSUCHNICK

           ERR_NOTONCHANNEL                ERR_KEYSET

           RPL_BANLIST                     RPL_ENDOFBANLIST

           ERR_UNKNOWNMODE                 ERR_NOSUCHCHANNEL


           ERR_USERSDONTMATCH              RPL_UMODEIS

           ERR_UMODEUNKNOWNFLAG


   Examples:


           Use of Channel Modes:


MODE #Finnish +im               ; Makes #Finnish channel moderated and

                                'invite-only'.


MODE #Finnish +o Kilroy         ; Gives 'chanop' privileges to Kilroy on




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                                channel #Finnish.


MODE #Finnish +v Wiz            ; Allow WiZ to speak on #Finnish.


MODE #Fins -s                   ; Removes 'secret' flag from channel

                                #Fins.


MODE #42 +k oulu                ; Set the channel key to "oulu".


MODE #eu-opers +l 10            ; Set the limit for the number of users

                                on channel to 10.


MODE &oulu +b                   ; list ban masks set for channel.


MODE &oulu +b *!*@*             ; prevent all users from joining.


MODE &oulu +b *!*@*.edu         ; prevent any user from a hostname

                                matching *.edu from joining.


        Use of user Modes:


:MODE WiZ -w                    ; turns reception of WALLOPS messages

                                off for WiZ.


:Angel MODE Angel +i            ; Message from Angel to make themselves

                                invisible.


MODE WiZ -o                     ; WiZ 'deopping' (removing operator

                                status).  The plain reverse of this

                                command ("MODE WiZ +o") must not be

                                allowed from users since would bypass

                                the OPER command.


4.2.4 Topic message


      Command: TOPIC

   Parameters: <channel> [<topic>]


   The TOPIC message is used to change or view the topic of a channel.

   The topic for channel <channel> is returned if there is no <topic>

   given.  If the <topic> parameter is present, the topic for that

   channel will be changed, if the channel modes permit this action.


   Numeric Replies:


           ERR_NEEDMOREPARAMS              ERR_NOTONCHANNEL

           RPL_NOTOPIC                     RPL_TOPIC

           ERR_CHANOPRIVSNEEDED




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   Examples:


   :Wiz TOPIC #test :New topic     ;User Wiz setting the topic.


   TOPIC #test :another topic      ;set the topic on #test to "another

                                   topic".


   TOPIC #test                     ; check the topic for #test.


4.2.5 Names message


      Command: NAMES

   Parameters: [<channel>{,<channel>}]


   By using the NAMES command, a user can list all nicknames that are

   visible to them on any channel that they can see.  Channel names

   which they can see are those which aren't private (+p) or secret (+s)

   or those which they are actually on.  The <channel> parameter

   specifies which channel(s) to return information about if valid.

   There is no error reply for bad channel names.


   If no <channel> parameter is given, a list of all channels and their

   occupants is returned.  At the end of this list, a list of users who

   are visible but either not on any channel or not on a visible channel

   are listed as being on `channel' "*".


   Numerics:


           RPL_NAMREPLY                    RPL_ENDOFNAMES


   Examples:


   NAMES #twilight_zone,#42        ; list visible users on #twilight_zone

                                   and #42 if the channels are visible to

                                   you.


   NAMES                           ; list all visible channels and users


4.2.6 List message


      Command: LIST

   Parameters: [<channel>{,<channel>} [<server>]]


   The list message is used to list channels and their topics.  If  the

   <channel>  parameter  is  used,  only  the  status  of  that  channel

   is displayed.  Private  channels  are  listed  (without  their

   topics)  as channel "Prv" unless the client generating the query is

   actually on that channel.  Likewise, secret channels are not listed




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   at  all  unless  the client is a member of the channel in question.


   Numeric Replies:


           ERR_NOSUCHSERVER                RPL_LISTSTART

           RPL_LIST                        RPL_LISTEND


   Examples:


   LIST                            ; List all channels.


   LIST #twilight_zone,#42         ; List channels #twilight_zone and #42


4.2.7 Invite message


      Command: INVITE

   Parameters: <nickname> <channel>


   The INVITE message is used to invite users to a channel.  The

   parameter <nickname> is the nickname of the person to be invited to

   the target channel <channel>.  There is no requirement that the

   channel the target user is being invited to must exist or be a valid

   channel.  To invite a user to a channel which is invite only (MODE

   +i), the client sending the invite must be recognised as being a

   channel operator on the given channel.


   Numeric Replies:


           ERR_NEEDMOREPARAMS              ERR_NOSUCHNICK

           ERR_NOTONCHANNEL                ERR_USERONCHANNEL

           ERR_CHANOPRIVSNEEDED

           RPL_INVITING                    RPL_AWAY


   Examples:


   :Angel INVITE Wiz #Dust         ; User Angel inviting WiZ to channel

                                   #Dust


   INVITE Wiz #Twilight_Zone       ; Command to invite WiZ to

                                   #Twilight_zone


4.2.8 Kick command


      Command: KICK

   Parameters: <channel> <user> [<comment>]


   The KICK command can be  used  to  forcibly  remove  a  user  from  a

   channel.   It  'kicks  them  out'  of the channel (forced PART).




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   Only a channel operator may kick another user out of a  channel.

   Each  server that  receives  a KICK message checks that it is valid

   (ie the sender is actually a  channel  operator)  before  removing

   the  victim  from  the channel.


   Numeric Replies:


           ERR_NEEDMOREPARAMS              ERR_NOSUCHCHANNEL

           ERR_BADCHANMASK                 ERR_CHANOPRIVSNEEDED

           ERR_NOTONCHANNEL


   Examples:


KICK &Melbourne Matthew         ; Kick Matthew from &Melbourne


KICK #Finnish John :Speaking English

                                ; Kick John from #Finnish using

                                "Speaking English" as the reason

                                (comment).


:WiZ KICK #Finnish John         ; KICK message from WiZ to remove John

                                from channel #Finnish


NOTE:

     It is possible to extend the KICK command parameters to the

following:


<channel>{,<channel>} <user>{,<user>} [<comment>]


4.3 Server queries and commands


   The server query group of commands has been designed to return

   information about any server which is connected to the network.  All

   servers connected must respond to these queries and respond

   correctly.  Any invalid response (or lack thereof) must be considered

   a sign of a broken server and it must be disconnected/disabled as

   soon as possible until the situation is remedied.


   In these queries, where a parameter appears as "<server>", it will

   usually mean it can be a nickname or a server or a wildcard name of

   some sort.  For each parameter, however, only one query and set of

   replies is to be generated.


4.3.1 Version message


      Command: VERSION

   Parameters: [<server>]





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   The VERSION message is used  to  query  the  version  of  the  server

   program.  An optional parameter <server> is used to query the version

   of the server program which a client is not directly connected to.


   Numeric Replies:


           ERR_NOSUCHSERVER                RPL_VERSION


   Examples:


   :Wiz VERSION *.se               ; message from Wiz to check the version

                                   of a server matching "*.se"


   VERSION tolsun.oulu.fi          ; check the version of server

                                   "tolsun.oulu.fi".


4.3.2 Stats message


      Command: STATS

   Parameters: [<query> [<server>]]


   The stats message is used to query statistics of certain server.  If

   <server> parameter is omitted, only the end of stats reply is sent

   back.  The implementation of this command is highly dependent on the

   server which replies, although the server must be able to supply

   information as described by the queries below (or similar).


   A query may be given by any single letter which is only checked by

   the destination server (if given as the <server> parameter) and is

   otherwise passed on by intermediate servers, ignored and unaltered.

   The following queries are those found in the current IRC

   implementation and provide a large portion of the setup information

   for that server.  Although these may not be supported in the same way

   by other versions, all servers should be able to supply a valid reply

   to a STATS query which is consistent with the reply formats currently

   used and the purpose of the query.


   The currently supported queries are:


           c - returns a list of servers which the server may connect

               to or allow connections from;

           h - returns a list of servers which are either forced to be

               treated as leaves or allowed to act as hubs;

           i - returns a list of hosts which the server allows a client

               to connect from;

           k - returns a list of banned username/hostname combinations

               for that server;

           l - returns a list of the server's connections, showing how




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               long each connection has been established and the traffic

               over that connection in bytes and messages for each

               direction;

           m - returns a list of commands supported by the server and

               the usage count for each if the usage count is non zero;

           o - returns a list of hosts from which normal clients may

               become operators;

           y - show Y (Class) lines from server's configuration file;

           u - returns a string showing how long the server has been up.


   Numeric Replies:


           ERR_NOSUCHSERVER

           RPL_STATSCLINE                  RPL_STATSNLINE

           RPL_STATSILINE                  RPL_STATSKLINE

           RPL_STATSQLINE                  RPL_STATSLLINE

           RPL_STATSLINKINFO               RPL_STATSUPTIME

           RPL_STATSCOMMANDS               RPL_STATSOLINE

           RPL_STATSHLINE                  RPL_ENDOFSTATS


   Examples:


STATS m                         ; check the command usage for the server

                                you are connected to


:Wiz STATS c eff.org            ; request by WiZ for C/N line

                                information from server eff.org


4.3.3 Links message


      Command: LINKS

   Parameters: [[<remote server>] <server mask>]


   With LINKS, a user can list all servers which are known by the server

   answering the query.  The returned list of servers must match the

   mask, or if no mask is given, the full list is returned.


   If <remote server> is given in addition to <server mask>, the LINKS

   command is forwarded to the first server found that matches that name

   (if any), and that server is then required to answer the query.


   Numeric Replies:


           ERR_NOSUCHSERVER

           RPL_LINKS                       RPL_ENDOFLINKS


   Examples:





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LINKS *.au                      ; list all servers which have a name

                                that matches *.au;


:WiZ LINKS *.bu.edu *.edu       ; LINKS message from WiZ to the first

                                server matching *.edu for a list of

                                servers matching *.bu.edu.


4.3.4 Time message


      Command: TIME

   Parameters: [<server>]


   The time message is used to query local time from the specified

   server. If the server parameter is not given, the server handling the

   command must reply to the query.


   Numeric Replies:


           ERR_NOSUCHSERVER                RPL_TIME


   Examples:


   TIME tolsun.oulu.fi             ; check the time on the server

                                   "tolson.oulu.fi"


   Angel TIME *.au                 ; user angel checking the time on a

                                   server matching "*.au"


4.3.5 Connect message


      Command: CONNECT

   Parameters: <target server> [<port> [<remote server>]]


   The CONNECT command can be used to force a server to try to establish

   a new connection to another server immediately.  CONNECT is a

   privileged command and is to be available only to IRC Operators.  If

   a remote server is given then the CONNECT attempt is made by that

   server to <target server> and <port>.


   Numeric Replies:


           ERR_NOSUCHSERVER                ERR_NOPRIVILEGES

           ERR_NEEDMOREPARAMS


   Examples:


CONNECT tolsun.oulu.fi          ; Attempt to connect a server to

                                tolsun.oulu.fi




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:WiZ CONNECT eff.org 6667 csd.bu.edu

                                ; CONNECT attempt by WiZ to get servers

                                eff.org and csd.bu.edu connected on port

                                6667.


4.3.6 Trace message


      Command: TRACE

   Parameters: [<server>]


   TRACE command is used to find the route to specific server.  Each

   server that processes this message must tell the sender about it by

   sending a reply indicating it is a pass-through link, forming a chain

   of replies similar to that gained from using "traceroute".  After

   sending this reply back, it must then send the TRACE message to the

   next server until given server is reached.  If the <server> parameter

   is omitted, it is recommended that TRACE command send a message to

   the sender telling which servers the current server has direct

   connection to.


   If the destination given by "<server>" is an actual server, then the

   destination server is required to report all servers and users which

   are connected to it, although only operators are permitted to see

   users present.  If the destination given by <server> is a nickname,

   they only a reply for that nickname is given.


   Numeric Replies:


           ERR_NOSUCHSERVER


   If the TRACE message is destined for another server, all intermediate

   servers must return a RPL_TRACELINK reply to indicate that the TRACE

   passed through it and where its going next.


           RPL_TRACELINK

   A TRACE reply may be composed of any number of the following numeric

   replies.


           RPL_TRACECONNECTING             RPL_TRACEHANDSHAKE

           RPL_TRACEUNKNOWN                RPL_TRACEOPERATOR

           RPL_TRACEUSER                   RPL_TRACESERVER

           RPL_TRACESERVICE                RPL_TRACENEWTYPE

           RPL_TRACECLASS


   Examples:


TRACE *.oulu.fi                 ; TRACE to a server matching *.oulu.fi





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:WiZ TRACE AngelDust            ; TRACE issued by WiZ to nick AngelDust


4.3.7 Admin command


      Command: ADMIN

   Parameters: [<server>]


   The admin message is used to find the name of the administrator of

   the given server, or current server if <server> parameter is omitted.

   Each server must have the ability to forward ADMIN messages to other

   servers.


   Numeric Replies:


           ERR_NOSUCHSERVER

           RPL_ADMINME                     RPL_ADMINLOC1

           RPL_ADMINLOC2                   RPL_ADMINEMAIL


   Examples:


   ADMIN tolsun.oulu.fi            ; request an ADMIN reply from

                                   tolsun.oulu.fi


   :WiZ ADMIN *.edu                ; ADMIN request from WiZ for first

                                   server found to match *.edu.


4.3.8 Info command


      Command: INFO

   Parameters: [<server>]


   The INFO command is required to return information which describes

   the server: its version, when it was compiled, the patchlevel, when

   it was started, and any other miscellaneous information which may be

   considered to be relevant.


   Numeric Replies:


           ERR_NOSUCHSERVER

           RPL_INFO                        RPL_ENDOFINFO


   Examples:


   INFO csd.bu.edu                 ; request an INFO reply from

   csd.bu.edu


   :Avalon INFO *.fi               ; INFO request from Avalon for first

                                   server found to match *.fi.




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   INFO Angel                      ; request info from the server that

                                   Angel is connected to.


4.4 Sending messages


   The main purpose of the IRC protocol is to provide a base for clients

   to communicate with each other.  PRIVMSG and NOTICE are the only

   messages available which actually perform delivery of a text message

   from one client to another - the rest just make it possible and try

   to ensure it happens in a reliable and structured manner.


4.4.1 Private messages


      Command: PRIVMSG

   Parameters: <receiver>{,<receiver>} <text to be sent>


   PRIVMSG is used to send private messages between users.  <receiver>

   is the nickname of the receiver of the message.  <receiver> can also

   be a list of names or channels separated with commas.


   The <receiver> parameter may also me a host mask  (#mask)  or  server

   mask  ($mask).   In  both cases the server will only send the PRIVMSG

   to those who have a server or host matching the mask.  The mask  must

   have at  least  1  (one)  "."  in it and no wildcards following the

   last ".".  This requirement exists to prevent people sending messages

   to  "#*"  or "$*",  which  would  broadcast  to  all  users; from

   experience, this is abused more than used responsibly and properly.

   Wildcards are  the  '*' and  '?'   characters.   This  extension  to

   the PRIVMSG command is only available to Operators.


   Numeric Replies:


           ERR_NORECIPIENT                 ERR_NOTEXTTOSEND

           ERR_CANNOTSENDTOCHAN            ERR_NOTOPLEVEL

           ERR_WILDTOPLEVEL                ERR_TOOMANYTARGETS

           ERR_NOSUCHNICK

           RPL_AWAY


   Examples:


:Angel PRIVMSG Wiz :Hello are you receiving this message ?

                                ; Message from Angel to Wiz.


PRIVMSG Angel :yes I'm receiving it !receiving it !'u>(768u+1n) .br ;

                                Message to Angel.


PRIVMSG jto@tolsun.oulu.fi :Hello !

                                ; Message to a client on server




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                                tolsun.oulu.fi with username of "jto".


PRIVMSG $*.fi :Server tolsun.oulu.fi rebooting.

                                ; Message to everyone on a server which

                                has a name matching *.fi.


PRIVMSG #*.edu :NSFNet is undergoing work, expect interruptions

                                ; Message to all users who come from a

                                host which has a name matching *.edu.


4.4.2 Notice


      Command: NOTICE

   Parameters: <nickname> <text>


   The NOTICE message is used similarly to PRIVMSG.  The difference

   between NOTICE and PRIVMSG is that automatic replies must never be

   sent in response to a NOTICE message.  This rule applies to servers

   too - they must not send any error reply back to the client on

   receipt of a notice.  The object of this rule is to avoid loops

   between a client automatically sending something in response to

   something it received.  This is typically used by automatons (clients

   with either an AI or other interactive program controlling their

   actions) which are always seen to be replying lest they end up in a

   loop with another automaton.


   See PRIVMSG for more details on replies and examples.


4.5 User based queries


   User queries are a group of commands which are primarily concerned

   with finding details on a particular user or group users.  When using

   wildcards with any of these commands, if they match, they will only

   return information on users who are 'visible' to you.  The visibility

   of a user is determined as a combination of the user's mode and the

   common set of channels you are both on.


4.5.1 Who query


      Command: WHO

   Parameters: [<name> [<o>]]


   The WHO message is used by a client to generate a query which returns

   a list of information which 'matches' the <name> parameter given by

   the client.  In the absence of the <name> parameter, all visible

   (users who aren't invisible (user mode +i) and who don't have a

   common channel with the requesting client) are listed.  The same

   result can be achieved by using a <name> of "0" or any wildcard which




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   will end up matching every entry possible.


   The <name> passed to WHO is matched against users' host, server, real

   name and nickname if the channel <name> cannot be found.


   If the "o" parameter is passed only operators are returned according

   to the name mask supplied.


   Numeric Replies:


           ERR_NOSUCHSERVER

           RPL_WHOREPLY                    RPL_ENDOFWHO


   Examples:


   WHO *.fi                        ; List all users who match against

                                   "*.fi".


   WHO jto* o                      ; List all users with a match against

                                   "jto*" if they are an operator.


4.5.2 Whois query


      Command: WHOIS

   Parameters: [<server>] <nickmask>[,<nickmask>[,...]]


   This message is used to query information about particular user.  The

   server will answer this message with several numeric messages

   indicating different statuses of each user which matches the nickmask

   (if you are entitled to see them).  If no wildcard is present in the

   <nickmask>, any information about that nick which you are allowed to

   see is presented.  A comma (',') separated list of nicknames may be

   given.


   The latter version sends the query to a specific server.  It is

   useful if you want to know how long the user in question has been

   idle as only local server (ie. the server the user is directly

   connected to) knows that information, while everything else is

   globally known.


   Numeric Replies:


           ERR_NOSUCHSERVER                ERR_NONICKNAMEGIVEN

           RPL_WHOISUSER                   RPL_WHOISCHANNELS

           RPL_WHOISCHANNELS               RPL_WHOISSERVER

           RPL_AWAY                        RPL_WHOISOPERATOR

           RPL_WHOISIDLE                   ERR_NOSUCHNICK

           RPL_ENDOFWHOIS




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   Examples:


   WHOIS wiz                       ; return available user information

                                   about nick WiZ


   WHOIS eff.org trillian          ; ask server eff.org for user

                                   information about trillian


4.5.3 Whowas


      Command: WHOWAS

   Parameters: <nickname> [<count> [<server>]]


   Whowas asks for information about a nickname which no longer exists.

   This may either be due to a nickname change or the user leaving IRC.

   In response to this query, the server searches through its nickname

   history, looking for any nicks which are lexically the same (no wild

   card matching here).  The history is searched backward, returning the

   most recent entry first.  If there are multiple entries, up to

   <count> replies will be returned (or all of them if no <count>

   parameter is given).  If a non-positive number is passed as being

   <count>, then a full search is done.


   Numeric Replies:


           ERR_NONICKNAMEGIVEN             ERR_WASNOSUCHNICK

           RPL_WHOWASUSER                  RPL_WHOISSERVER

           RPL_ENDOFWHOWAS


   Examples:


   WHOWAS Wiz                      ; return all information in the nick

                                   history about nick "WiZ";


   WHOWAS Mermaid 9                ; return at most, the 9 most recent

                                   entries in the nick history for

                                   "Mermaid";


   WHOWAS Trillian 1 *.edu         ; return the most recent history for

                                   "Trillian" from the first server found

                                   to match "*.edu".


4.6 Miscellaneous messages


   Messages in this category do not fit into any of the above categories

   but are nonetheless still a part of and required by the protocol.






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4.6.1 Kill message


      Command: KILL

   Parameters: <nickname> <comment>


   The KILL message is used to cause a client-server connection to be

   closed by the server which has the actual connection.  KILL is used

   by servers when they encounter a duplicate entry in the list of valid

   nicknames and is used to remove both entries.  It is also available

   to operators.


   Clients which have automatic reconnect algorithms effectively make

   this command useless since the disconnection is only brief.  It does

   however break the flow of data and can be used to stop large amounts

   of being abused, any user may elect to receive KILL messages

   generated for others to keep an 'eye' on would be trouble spots.


   In an arena where nicknames are required to be globally unique at all

   times, KILL messages are sent whenever 'duplicates' are detected

   (that is an attempt to register two users with the same nickname) in

   the hope that both of them will disappear and only 1 reappear.


   The comment given must reflect the actual reason for the KILL.  For

   server-generated KILLs it usually is made up of details concerning

   the origins of the two conflicting nicknames.  For users it is left

   up to them to provide an adequate reason to satisfy others who see

   it.  To prevent/discourage fake KILLs from being generated to hide

   the identify of the KILLer, the comment also shows a 'kill-path'

   which is updated by each server it passes through, each prepending

   its name to the path.


   Numeric Replies:


           ERR_NOPRIVILEGES                ERR_NEEDMOREPARAMS

           ERR_NOSUCHNICK                  ERR_CANTKILLSERVER



   KILL David (csd.bu.edu <- tolsun.oulu.fi)

                                   ; Nickname collision between csd.bu.edu

                                   and tolson.oulu.fi



   NOTE:

   It is recommended that only Operators be allowed to kill other users

   with KILL message.  In an ideal world not even operators would need

   to do this and it would be left to servers to deal with.






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4.6.2 Ping message


      Command: PING

   Parameters: <server1> [<server2>]


   The PING message is used to test the presence of an active client at

   the other end of the connection.  A PING message is sent at regular

   intervals if no other activity detected coming from a connection.  If

   a connection fails to respond to a PING command within a set amount

   of time, that connection is closed.


   Any client which receives a PING message must respond to <server1>

   (server which sent the PING message out) as quickly as possible with

   an appropriate PONG message to indicate it is still there and alive.

   Servers should not respond to PING commands but rely on PINGs from

   the other end of the connection to indicate the connection is alive.

   If the <server2> parameter is specified, the PING message gets

   forwarded there.


   Numeric Replies:


           ERR_NOORIGIN                    ERR_NOSUCHSERVER


   Examples:


   PING tolsun.oulu.fi             ; server sending a PING message to

                                   another server to indicate it is still

                                   alive.


   PING WiZ                        ; PING message being sent to nick WiZ