RFC 2812 (rfc2812) - Internet Relay Chat: Client Protocol
Description: RFC 2812 - Internet Relay Chat: Client Protocol

# RFC 2812 (RFC2812)

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### RFC 2812 - Internet Relay Chat: Client Protocol

    Network Working Group                                            C. Kalt
    Request for Comments: 2812                                    April 2000
    Updates: 1459
    Category: Informational

                      Internet Relay Chat: Client Protocol

    Status of this Memo

       This memo provides information for the Internet community.  It does
       not specify an Internet standard of any kind.  Distribution of this
       memo is unlimited.

    Copyright Notice

       Copyright (C) The Internet Society (2000).  All Rights Reserved.

    IESG NOTE:

       The IRC protocol itself enables several possibilities of transferring
       data between clients, and just like with other transfer mechanisms
       like email, the receiver of the data has to be careful about how the
       data is handled. For more information on security issues with the IRC
       protocol, see for example http://www.irchelp.org/irchelp/security/.

    Abstract

       The IRC (Internet Relay Chat) protocol is for use with text based
       conferencing; the simplest client being any socket program capable of
       connecting to the server.

       This document defines the Client Protocol, and assumes that the
       reader is familiar with the IRC Architecture [IRC-ARCH].

    Table of Contents

       1.  Labels .....................................................   3
          1.1  Servers ................................................   3
          1.2  Clients ................................................   3
             1.2.1  Users .............................................   4
                1.2.1.1  Operators ....................................   4
             1.2.2  Services ..........................................   4
          1.3  Channels ...............................................   4
       2.  The IRC Client Specification ...............................   5
          2.1  Overview ...............................................   5
          2.2  Character codes ........................................   5
          2.3  Messages ...............................................   5

             2.3.1  Message format in Augmented BNF ...................   6
          2.4  Numeric replies ........................................   8
          2.5  Wildcard expressions ...................................   9
       3.  Message Details ............................................   9
          3.1  Connection Registration ................................  10
             3.1.1  Password message ..................................  10
             3.1.2  Nick message ......................................  10
             3.1.3  User message ......................................  11
             3.1.4  Oper message ......................................  12
             3.1.5  User mode message .................................  12
             3.1.6  Service message ...................................  13
             3.1.7  Quit ..............................................  14
             3.1.8  Squit .............................................  15
          3.2  Channel operations .....................................  15
             3.2.1  Join message ......................................  16
             3.2.2  Part message ......................................  17
             3.2.3  Channel mode message ..............................  18
             3.2.4  Topic message .....................................  19
             3.2.5  Names message .....................................  20
             3.2.6  List message ......................................  21
             3.2.7  Invite message ....................................  21
             3.2.8  Kick command ......................................  22
          3.3  Sending messages .......................................  23
             3.3.1  Private messages ..................................  23
             3.3.2  Notice ............................................  24
          3.4  Server queries and commands ............................  25
             3.4.1  Motd message ......................................  25
             3.4.2  Lusers message ....................................  25
             3.4.3  Version message ...................................  26
             3.4.4  Stats message .....................................  26
             3.4.5  Links message .....................................  27
             3.4.6  Time message ......................................  28
             3.4.7  Connect message ...................................  28
             3.4.8  Trace message .....................................  29
             3.4.9  Admin command .....................................  30
             3.4.10 Info command ......................................  31
          3.5  Service Query and Commands .............................  31
             3.5.1  Servlist message ..................................  31
             3.5.2  Squery ............................................  32
          3.6  User based queries .....................................  32
             3.6.1  Who query .........................................  32
             3.6.2  Whois query .......................................  33
             3.6.3  Whowas ............................................  34
          3.7  Miscellaneous messages .................................  34
             3.7.1  Kill message ......................................  35
             3.7.2  Ping message ......................................  36
             3.7.3  Pong message ......................................  37
             3.7.4  Error .............................................  37

       4.  Optional features ..........................................  38
          4.1  Away ...................................................  38
          4.2  Rehash message .........................................  39
          4.3  Die message ............................................  39
          4.4  Restart message ........................................  40
          4.5  Summon message .........................................  40
          4.6  Users ..................................................  41
          4.7  Operwall message .......................................  41
          4.8  Userhost message .......................................  42
          4.9  Ison message ...........................................  42
       5.  Replies ....................................................  43
          5.1  Command responses ......................................  43
          5.2  Error Replies ..........................................  53
          5.3  Reserved numerics ......................................  59
       6.  Current implementations ....................................  60
       7.  Current problems ...........................................  60
          7.1  Nicknames ..............................................  60
          7.2  Limitation of wildcards ................................  61
          7.3  Security considerations ................................  61
       8.  Current support and availability ...........................  61
       9.  Acknowledgements ...........................................  61
       10.  References ................................................  62
       11.  Author's Address ..........................................  62
       12.  Full Copyright Statement ..................................  63

    1. Labels

       This section defines the identifiers used for the various components
       of the IRC protocol.

    1.1 Servers

       Servers are uniquely identified by their name, which has a maximum
       length of sixty three (63) characters.  See the protocol grammar
       rules (section 2.3.1) for what may and may not be used in a server
       name.

    1.2 Clients

       For each client all servers MUST have the following information: a
       netwide unique identifier (whose format depends on the type of
       client) and the server which introduced the client.

    1.2.1 Users

       Each user is distinguished from other users by a unique nickname
       having a maximum length of nine (9) characters.  See the protocol
       grammar rules (section 2.3.1) for what may and may not be used in a
       nickname.

       While the maximum length is limited to nine characters, clients
       SHOULD accept longer strings as they may become used in future
       evolutions of the protocol.

    1.2.1.1 Operators

       To allow a reasonable amount of order to be kept within the IRC
       network, a special class of users (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 often necessary.  Operators SHOULD be able to perform
       basic network tasks such as disconnecting and reconnecting servers as
       needed.  In recognition of this need, the protocol discussed herein
       provides for operators only to be able to perform such functions.
       See sections 3.1.8 (SQUIT) and 3.4.7 (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 very delicate since its abuse is both
       destructive and annoying, and its benefits close to inexistent.  For
       further details on this type of action, see section 3.7.1 (KILL).

    1.2.2 Services

       Each service is distinguished from other services by a service name
       composed of a nickname and a server name.  As for users, the nickname
       has a maximum length of nine (9) characters.  See the protocol
       grammar rules (section 2.3.1) for what may and may not be used in a
       nickname.

    1.3 Channels

       Channels names are strings (beginning with a '&', '#', '+' or '!'
       character) of length up to fifty (50) characters.  Apart from the
       requirement that the first character is either '&', '#', '+' or '!',
       the only restriction on a channel name is that it SHALL NOT contain
       any spaces (' '), a control G (^G or ASCII 7), a comma (',').  Space
       is used as parameter separator and command is used as a list item
       separator by the protocol).  A colon (':') can also be used as a
       delimiter for the channel mask.  Channel names are case insensitive.

       See the protocol grammar rules (section 2.3.1) for the exact syntax
       of a channel name.

       Each prefix characterizes a different channel type.  The definition
       of the channel types is not relevant to the client-server protocol
       and thus it is beyond the scope of this document.  More details can
       be found in "Internet Relay Chat: Channel Management" [IRC-CHAN].

    2. The IRC Client Specification

    2.1 Overview

       The protocol as described herein is for use only with client to
       server connections when the client registers as a user.

    2.2 Character codes

       No specific character set is specified. The protocol is based on 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 US-ASCII terminal and a
       telnet connection.

       Because of IRC's Scandinavian 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 or channel names.

    2.3 Messages

       Servers and clients send each other 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 by nature.

       Each IRC message may consist of up to three main parts: the prefix
       (OPTIONAL), the command, and the command parameters (maximum of
       fifteen (15)).  The prefix, command, and all parameters are separated
       by one ASCII space character (0x20) each.

       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
       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 from.  Clients SHOULD NOT use a prefix when sending a
       message; if they use one, the only valid prefix is the registered
       nickname associated with the client.

       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 of message lines.  See section 6 for more details about
       current implementations.

    2.3.1 Message format in Augmented 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 (<params>).

        The Augmented BNF representation for this is:

        message    =  [ ":" prefix SPACE ] command [ params ] crlf
        prefix     =  servername / ( nickname [ [ "!" user ] "@" host ] )
        command    =  1*letter / 3digit
        params     =  *14( SPACE middle ) [ SPACE ":" trailing ]
                   =/ 14( SPACE middle ) [ SPACE [ ":" ] trailing ]

        nospcrlfcl =  %x01-09 / %x0B-0C / %x0E-1F / %x21-39 / %x3B-FF
                        ; any octet except NUL, CR, LF, " " and ":"
        middle     =  nospcrlfcl *( ":" / nospcrlfcl )
        trailing   =  *( ":" / " " / nospcrlfcl )

        SPACE      =  %x20        ; space character
        crlf       =  %x0D %x0A   ; "carriage return" "linefeed"

       NOTES:
          1) 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 the parameter.

          2) The NUL (%x00) character is not special in message framing, and
             basically could end up inside a parameter, but it would cause
             extra complexities in normal C string handling. Therefore, NUL
             is not allowed within messages.

       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     =  nickname / server
      msgtarget  =  msgto *( "," msgto )
      msgto      =  channel / ( user [ "%" host ] "@" servername )
      msgto      =/ ( user "%" host ) / targetmask
      msgto      =/ nickname / ( nickname "!" user "@" host )
      channel    =  ( "#" / "+" / ( "!" channelid ) / "&" ) chanstring
                    [ ":" chanstring ]
      servername =  hostname
      host       =  hostname / hostaddr
      hostname   =  shortname *( "." shortname )
      shortname  =  ( letter / digit ) *( letter / digit / "-" )
                    *( letter / digit )
                      ; as specified in RFC 1123 [HNAME]
      hostaddr   =  ip4addr / ip6addr
      ip4addr    =  1*3digit "." 1*3digit "." 1*3digit "." 1*3digit
      ip6addr    =  1*hexdigit 7( ":" 1*hexdigit )
      ip6addr    =/ "0:0:0:0:0:" ( "0" / "FFFF" ) ":" ip4addr
      nickname   =  ( letter / special ) *8( letter / digit / special / "-" )
      targetmask =  ( "$" / "#" ) mask
                      ; see details on allowed masks in section 3.3.1
      chanstring =  %x01-07 / %x08-09 / %x0B-0C / %x0E-1F / %x21-2B
      chanstring =/ %x2D-39 / %x3B-FF
                      ; any octet except NUL, BELL, CR, LF, " ", "," and ":"
      channelid  = 5( %x41-5A / digit )   ; 5( A-Z / 0-9 )

      Other parameter syntaxes are:

      user       =  1*( %x01-09 / %x0B-0C / %x0E-1F / %x21-3F / %x41-FF )
                      ; any octet except NUL, CR, LF, " " and "@"
      key        =  1*23( %x01-05 / %x07-08 / %x0C / %x0E-1F / %x21-7F )
                      ; any 7-bit US_ASCII character,
                      ; except NUL, CR, LF, FF, h/v TABs, and " "
      letter     =  %x41-5A / %x61-7A       ; A-Z / a-z
      digit      =  %x30-39                 ; 0-9
      hexdigit   =  digit / "A" / "B" / "C" / "D" / "E" / "F"
      special    =  %x5B-60 / %x7B-7D
                       ; "[", "]", "\", "`", "_", "^", "{", "|", "}"

      NOTES:
          1) The <hostaddr> syntax is given here for the sole purpose of
             indicating the format to follow for IP addresses.  This
             reflects the fact that the only available implementations of
             this protocol uses TCP/IP as underlying network protocol but is
             not meant to prevent other protocols to be used.

          2) <hostname> has a maximum length of 63 characters.  This is a
             limitation of the protocol as internet hostnames (in
             particular) can be longer.  Such restriction is necessary
             because IRC messages are limited to 512 characters in length.
             Clients connecting from a host which name is longer than 63
             characters are registered using the host (numeric) address
             instead of the host name.

          3) Some parameters used in the following sections of this
             documents are not defined here as there is nothing specific
             about them besides the name that is used for convenience.
             These parameters follow the general syntax defined for
             <params>.

    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. 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 5 (Replies).

    2.5 Wildcard expressions

       When wildcards are allowed in a string, it is referred as a "mask".

       For string matching purposes, the protocol allows the use of two
       special characters: '?' (%x3F) to match one and only one character,
       and '*' (%x2A) to match any number of any characters.  These two
       characters can be escaped using the character '\' (%x5C).

       The Augmented BNF syntax for this is:

        mask       =  *( nowild / noesc wildone / noesc wildmany )
        wildone    =  %x3F
        wildmany   =  %x2A
        nowild     =  %x01-29 / %x2B-3E / %x40-FF
                        ; any octet except NUL, "*", "?"
        noesc      =  %x01-5B / %x5D-FF
                        ; any octet except NUL and "\"
        matchone   =  %x01-FF
                        ; matches wildone
        matchmany  =  *matchone
                        ; matches wildmany

       Examples:

       a?c         ; Matches any string of 3 characters in length starting
                   with "a" and ending with "c"

       a*c         ; Matches any string of at least 2 characters in length
                   starting with "a" and ending with "c"

    3. Message Details

       On the following pages there 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 returned, it means that the
       target of the message could not be found.  The server MUST NOT send
       any other replies after this error for that command.

       The server to which a client is connected is required to parse the
       complete message, and return any appropriate errors.

       If multiple parameters is presented, then each MUST be checked for
       validity and appropriate responses MUST be sent back to the client.
       In the case of incorrect messages which use parameter lists with
       comma as an item separator, a reply MUST be sent for each item.

    3.1 Connection Registration

       The commands described here are used to register a connection with an
       IRC server as a user as well as to correctly disconnect.

       A "PASS" command is not required for a client connection to be
       registered, but it MUST precede the latter of the NICK/USER
       combination (for a user connection) or the SERVICE command (for a
       service connection). The RECOMMENDED order for a client to register
       is as follows:

                               1. Pass message
               2. Nick message                 2. Service message
               3. User message

       Upon success, the client will receive an RPL_WELCOME (for users) or
       RPL_YOURESERVICE (for services) message indicating that the
       connection is now registered and known the to the entire IRC network.
       The reply message MUST contain the full client identifier upon which
       it was registered.

    3.1.1 Password message

          Command: PASS
       Parameters: <password>

       The PASS command is used to set a 'connection password'.  The
       optional password can and MUST be set before any attempt to register
       the connection is made.  Currently this requires that user send a
       PASS command before sending the NICK/USER combination.

       Numeric Replies:

               ERR_NEEDMOREPARAMS              ERR_ALREADYREGISTRED

       Example:

               PASS secretpasswordhere

    3.1.2 Nick message

          Command: NICK
       Parameters: <nickname>

       NICK command is used to give user a nickname or change the existing
       one.

       Numeric Replies:

               ERR_NONICKNAMEGIVEN             ERR_ERRONEUSNICKNAME
               ERR_NICKNAMEINUSE               ERR_NICKCOLLISION
               ERR_UNAVAILRESOURCE             ERR_RESTRICTED

       Examples:

       NICK Wiz                ; Introducing new nick "Wiz" if session is
                               still unregistered, or user changing his
                               nickname to "Wiz"

       :WiZ!jto@tolsun.oulu.fi NICK Kilroy
                               ; Server telling that WiZ changed his
                               nickname to Kilroy.

    3.1.3 User message

          Command: USER
       Parameters: <user> <mode> <unused> <realname>

       The USER command is used at the beginning of connection to specify
       the username, hostname and realname of a new user.

       The <mode> parameter should be a numeric, and can be used to
       automatically set user modes when registering with the server.  This
       parameter is a bitmask, with only 2 bits having any signification: if
       the bit 2 is set, the user mode 'w' will be set and if the bit 3 is
       set, the user mode 'i' will be set.  (See Section 3.1.5 "User
       Modes").

       The <realname> may contain space characters.

       Numeric Replies:

               ERR_NEEDMOREPARAMS              ERR_ALREADYREGISTRED

       Example:

       USER guest 0 * :Ronnie Reagan   ; User registering themselves with a
                                       username of "guest" and real name
                                       "Ronnie Reagan".

       USER guest 8 * :Ronnie Reagan   ; User registering themselves with a
                                       username of "guest" and real name
                                       "Ronnie Reagan", and asking to be set
                                       invisible.

    3.1.4 Oper message

          Command: OPER
       Parameters: <name> <password>

       A normal user uses the OPER command to obtain operator privileges.
       The combination of <name> and <password> are REQUIRED to gain
       Operator privileges.  Upon success, the user will receive a MODE
       message (see section 3.1.5) indicating the new user modes.

       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.

    3.1.5 User mode message

          Command: MODE
       Parameters: <nickname>
                   *( ( "+" / "-" ) *( "i" / "w" / "o" / "O" / "r" ) )

       The user MODE's 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 MUST only be accepted if both the sender of the
       message and the nickname given as a parameter are both the same.  If
       no other parameter is given, then the server will return the current
       settings for the nick.

          The available modes are as follows:

               a - user is flagged as away;
               i - marks a users as invisible;
               w - user receives wallops;
               r - restricted user connection;
               o - operator flag;
               O - local operator flag;
               s - marks a user for receipt of server notices.

       Additional modes may be available later on.

       The flag 'a' SHALL NOT be toggled by the user using the MODE command,
       instead use of the AWAY command is REQUIRED.

       If a user attempts to make themselves an operator using the "+o" or
       "+O" flag, the attempt SHOULD be ignored as users could bypass the
       authentication mechanisms of the OPER command.  There is no
       restriction, however, on anyone `deopping' themselves (using "-o" or
       "-O").

       On the other hand, if a user attempts to make themselves unrestricted
       using the "-r" flag, the attempt SHOULD be ignored.  There is no
       restriction, however, on anyone `deopping' themselves (using "+r").
       This flag is typically set by the server upon connection for
       administrative reasons.  While the restrictions imposed are left up
       to the implementation, it is typical that a restricted user not be
       allowed to change nicknames, nor make use of the channel operator
       status on channels.

       The flag 's' is obsolete but MAY still be used.

       Numeric Replies:

               ERR_NEEDMOREPARAMS              ERR_USERSDONTMATCH
               ERR_UMODEUNKNOWNFLAG            RPL_UMODEIS

       Examples:

       MODE WiZ -w                     ; Command by WiZ to turn off
                                       reception of WALLOPS messages.

       MODE Angel +i                   ; Command from Angel to make herself
                                       invisible.

       MODE WiZ -o                     ; WiZ 'deopping' (removing operator
                                       status).

    3.1.6 Service message

          Command: SERVICE
       Parameters: <nickname> <reserved> <distribution> <type>
                   <reserved> <info>

       The SERVICE command to register a new service.  Command parameters
       specify the service nickname, distribution, type and info of a new
       service.

       The <distribution> parameter is used to specify the visibility of a
       service.  The service may only be known to servers which have a name
       matching the distribution.  For a matching server to have knowledge
       of the service, the network path between that server and the server
       on which the service is connected MUST be composed of servers which
       names all match the mask.

       The <type> parameter is currently reserved for future usage.

       Numeric Replies:

               ERR_ALREADYREGISTRED            ERR_NEEDMOREPARAMS
               ERR_ERRONEUSNICKNAME
               RPL_YOURESERVICE                RPL_YOURHOST
               RPL_MYINFO

       Example:

       SERVICE dict * *.fr 0 0 :French Dictionary ; Service registering
                                       itself with a name of "dict".  This
                                       service will only be available on
                                       servers which name matches "*.fr".

    3.1.7 Quit

          Command: QUIT
       Parameters: [ <Quit Message> ]

       A client session is terminated with a quit message.  The server
       acknowledges this by sending an ERROR message to the client.

       Numeric Replies:

               None.

       Example:

       QUIT :Gone to have lunch        ; Preferred message format.

       :syrk!kalt@millennium.stealth.net QUIT :Gone to have lunch ; User
                                       syrk has quit IRC to have lunch.

    3.1.8 Squit

          Command: SQUIT
       Parameters: <server> <comment>

       The SQUIT command is available only to operators.  It is used to
       disconnect server links.  Also servers can generate SQUIT messages on
       error conditions.  A SQUIT message may also target a remote server
       connection.  In this case, the SQUIT message will simply be sent to
       the remote server without affecting the servers in between the
       operator and the remote server.

       The <comment> SHOULD be supplied by all operators who execute a SQUIT
       for a remote server.  The server ordered to disconnect its peer
       generates a WALLOPS message with <comment> included, so that other
       users may be aware of the reason of this action.

       Numeric replies:

               ERR_NOPRIVILEGES                ERR_NOSUCHSERVER
               ERR_NEEDMOREPARAMS

       Examples:

       SQUIT tolsun.oulu.fi :Bad Link ?  ; Command to uplink of the server
                                       tolson.oulu.fi to terminate its
                                       connection with comment "Bad Link".

       :Trillian SQUIT cm22.eng.umd.edu :Server out of control ; Command
                                       from Trillian from to disconnect
                                       "cm22.eng.umd.edu" from the net with
                                       comment "Server out of control".

    3.2 Channel operations

       This group of messages is concerned with manipulating channels, their
       properties (channel modes), and their contents (typically users).
       For this reason, these messages SHALL NOT be made available to
       services.

       All of these messages are requests which will or will not be granted
       by the server.  The server MUST send a reply informing the user
       whether the request was granted, denied or generated an error.  When
       the server grants the request, the message is typically sent back
       (eventually reformatted) to the user with the prefix set to the user
       itself.

       The rules governing how channels are managed are enforced by the
       servers.  These rules are beyond the scope of this document.  More
       details are found in "Internet Relay Chat: Channel Management" [IRC-
       CHAN].

    3.2.1 Join message

          Command: JOIN
       Parameters: ( <channel> *( "," <channel> ) [ <key> *( "," <key> ) ] )
                   / "0"

       The JOIN command is used by a user to request to start listening to
       the specific channel.  Servers MUST be able to parse arguments in the
       form of a list of target, but SHOULD NOT use lists when sending JOIN
       messages to clients.

       Once a user has joined a channel, he receives information about
       all commands his server receives affecting the channel.  This
       includes JOIN, MODE, KICK, PART, QUIT and of course PRIVMSG/NOTICE.
       This allows channel members to keep track of the other channel
       members, as well as channel modes.

       If a JOIN is successful, the user receives a JOIN message as
       confirmation and 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.

       Note that this message accepts a special argument ("0"), which is
       a special request to leave all channels the user is currently a member
       of.  The server will process this message as if the user had sent
       a PART command (See Section 3.2.2) for each channel he is a member
       of.

       Numeric Replies:

               ERR_NEEDMOREPARAMS              ERR_BANNEDFROMCHAN
               ERR_INVITEONLYCHAN              ERR_BADCHANNELKEY
               ERR_CHANNELISFULL               ERR_BADCHANMASK
               ERR_NOSUCHCHANNEL               ERR_TOOMANYCHANNELS
               ERR_TOOMANYTARGETS              ERR_UNAVAILRESOURCE
               RPL_TOPIC

       Examples:

       JOIN #foobar                    ; Command to join channel #foobar.

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

       JOIN #foo,&bar fubar            ; Command to join channel #foo using
                                       key "fubar" and &bar using no key.

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

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

       JOIN 0                          ; Leave all currently joined
                                       channels.

       :WiZ!jto@tolsun.oulu.fi JOIN #Twilight_zone ; JOIN message from WiZ
                                       on channel #Twilight_zone

    3.2.2 Part message

          Command: PART
       Parameters: <channel> *( "," <channel> ) [ <Part Message> ]

       The PART command causes the user sending the message to be removed
       from the list of active members for all given channels listed in the
       parameter string.  If a "Part Message" is given, this will be sent
       instead of the default message, the nickname.  This request is always
       granted by the server.

       Servers MUST be able to parse arguments in the form of a list of
       target, but SHOULD NOT use lists when sending PART messages to
       clients.

       Numeric Replies:

               ERR_NEEDMOREPARAMS              ERR_NOSUCHCHANNEL
               ERR_NOTONCHANNEL

       Examples:

       PART #twilight_zone             ; Command to leave channel
                                       "#twilight_zone"

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

       :WiZ!jto@tolsun.oulu.fi PART #playzone :I lost
                                       ; User WiZ leaving channel
                                       "#playzone" with the message "I
                                       lost".

    3.2.3 Channel mode message

          Command: MODE
       Parameters: <channel> *( ( "-" / "+" ) *<modes> *<modeparams> )

       The MODE command is provided so that users may query and change the
       characteristics of a channel.  For more details on available modes
       and their uses, see "Internet Relay Chat: Channel Management" [IRC-
       CHAN].  Note that there is a maximum limit of three (3) changes per
       command for modes that take a parameter.

       Numeric Replies:

               ERR_NEEDMOREPARAMS              ERR_KEYSET
               ERR_NOCHANMODES                 ERR_CHANOPRIVSNEEDED
               ERR_USERNOTINCHANNEL            ERR_UNKNOWNMODE
               RPL_CHANNELMODEIS
               RPL_BANLIST                     RPL_ENDOFBANLIST
               RPL_EXCEPTLIST                  RPL_ENDOFEXCEPTLIST
               RPL_INVITELIST                  RPL_ENDOFINVITELIST
               RPL_UNIQOPIS

       The following examples are given to help understanding the syntax of
       the MODE command, but refer to modes defined in "Internet Relay Chat:
       Channel Management" [IRC-CHAN].

       Examples:

       MODE #Finnish +imI *!*@*.fi     ; Command to make #Finnish channel
                                       moderated and 'invite-only' with user
                                       with a hostname matching *.fi
                                       automatically invited.

       MODE #Finnish +o Kilroy         ; Command to give 'chanop' privileges
                                       to Kilroy on channel #Finnish.

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

       MODE #Fins -s                   ; Command to remove 'secret' flag
                                       from channel #Fins.

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

       MODE #42 -k oulu                ; Command to remove the "oulu"
                                       channel key on channel "#42".

       MODE #eu-opers +l 10            ; Command to set the limit for the
                                       number of users on channel
                                       "#eu-opers" to 10.

       :WiZ!jto@tolsun.oulu.fi MODE #eu-opers -l
                                       ; User "WiZ" removing the limit for
                                       the number of users on channel "#eu-
                                       opers".

       MODE &oulu +b                   ; Command to list ban masks set for
                                       the channel "&oulu".

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

       MODE &oulu +b *!*@*.edu +e *!*@*.bu.edu
                                       ; Command to prevent any user from a
                                       hostname matching *.edu from joining,
                                       except if matching *.bu.edu

       MODE #bu +be *!*@*.edu *!*@*.bu.edu
                                       ; Comment to prevent any user from a
                                       hostname matching *.edu from joining,
                                       except if matching *.bu.edu

       MODE #meditation e              ; Command to list exception masks set
                                       for the channel "#meditation".

       MODE #meditation I              ; Command to list invitations masks
                                       set for the channel "#meditation".

       MODE !12345ircd O               ; Command to ask who the channel
                                       creator for "!12345ircd" is

    3.2.4 Topic message

          Command: TOPIC
       Parameters: <channel> [ <topic> ]

       The TOPIC command 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 this action is allowed for the user
       requesting it.  If the <topic> parameter is an empty string, the
       topic for that channel will be removed.

       Numeric Replies:

               ERR_NEEDMOREPARAMS              ERR_NOTONCHANNEL
               RPL_NOTOPIC                     RPL_TOPIC
               ERR_CHANOPRIVSNEEDED            ERR_NOCHANMODES

       Examples:

       :WiZ!jto@tolsun.oulu.fi TOPIC #test :New topic ; User Wiz setting the
                                       topic.

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

       TOPIC #test :                   ; Command to clear the topic on
                                       #test.

       TOPIC #test                     ; Command to check the topic for
                                       #test.

    3.2.5 Names message

          Command: NAMES
       Parameters: [ <channel> *( "," <channel> ) [ <target> ] ]

       By using the NAMES command, a user can list all nicknames that are
       visible to him. For more details on what is visible and what is not,
       see "Internet Relay Chat: Channel Management" [IRC-CHAN].  The
       <channel> parameter specifies which channel(s) to return information
       about.  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' "*".

       If the <target> parameter is specified, the request is forwarded to
       that server which will generate the reply.

       Wildcards are allowed in the <target> parameter.

       Numerics:

               ERR_TOOMANYMATCHES              ERR_NOSUCHSERVER
               RPL_NAMREPLY                    RPL_ENDOFNAMES

       Examples:

       NAMES #twilight_zone,#42        ; Command to list visible users on
                                       #twilight_zone and #42

       NAMES                           ; Command to list all visible
                                       channels and users

    3.2.6 List message

          Command: LIST
       Parameters: [ <channel> *( "," <channel> ) [ <target> ] ]

       The list command is used to list channels and their topics.  If the
       <channel> parameter is used, only the status of that channel is
       displayed.

       If the <target> parameter is specified, the request is forwarded to
       that server which will generate the reply.

       Wildcards are allowed in the <target> parameter.

       Numeric Replies:

               ERR_TOOMANYMATCHES              ERR_NOSUCHSERVER
               RPL_LIST                        RPL_LISTEND

       Examples:

       LIST                            ; Command to list all channels.

       LIST #twilight_zone,#42         ; Command to list channels
                                       #twilight_zone and #42

    3.2.7 Invite message

          Command: INVITE
       Parameters: <nickname> <channel>

       The INVITE command is used to invite a user 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.  However, if the channel exists, only members of the channel
       are allowed to invite other users.  When the channel has invite-only
       flag set, only channel operators may issue INVITE command.

       Only the user inviting and the user being invited will receive
       notification of the invitation.  Other channel members are not
       notified.  (This is unlike the MODE changes, and is occasionally the
       source of trouble for users.)

       Numeric Replies:

               ERR_NEEDMOREPARAMS              ERR_NOSUCHNICK
               ERR_NOTONCHANNEL                ERR_USERONCHANNEL
               ERR_CHANOPRIVSNEEDED
               RPL_INVITING                    RPL_AWAY

       Examples:

       :Angel!wings@irc.org INVITE Wiz #Dust

                                       ; Message to WiZ when he has been
                                       invited by user Angel to channel
                                       #Dust

       INVITE Wiz #Twilight_Zone       ; Command to invite WiZ to
                                       #Twilight_zone

    3.2.8 Kick command

          Command: KICK
       Parameters: <channel> *( "," <channel> ) <user> *( "," <user> )
                   [<comment>]

       The KICK command can be used to request the forced removal of a user
       from a channel.  It causes the <user> to PART from the <channel> by
       force.  For the message to be syntactically correct, there MUST be
       either one channel parameter and multiple user parameter, or as many
       channel parameters as there are user parameters.  If a "comment" is
       given, this will be sent instead of the default message, the nickname
       of the user issuing the KICK.

       The server MUST NOT send KICK messages with multiple channels or
       users to clients.  This is necessarily to maintain backward
       compatibility with old client software.

       Numeric Replies:

               ERR_NEEDMOREPARAMS              ERR_NOSUCHCHANNEL
               ERR_BADCHANMASK                 ERR_CHANOPRIVSNEEDED
               ERR_USERNOTINCHANNEL            ERR_NOTONCHANNEL

       Examples:

       KICK &Melbourne Matthew         ; Command to kick Matthew from
                                       &Melbourne

       KICK #Finnish John :Speaking English
                                       ; Command to kick John from #Finnish
                                       using "Speaking English" as the
                                       reason (comment).

       :WiZ!jto@tolsun.oulu.fi KICK #Finnish John
                                       ; KICK message on channel #Finnish
                                       from WiZ to remove John from channel

    3.3 Sending messages

       The main purpose of the IRC protocol is to provide a base for clients
       to communicate with each other.  PRIVMSG, NOTICE and SQUERY
       (described in Section 3.5 on Service Query and Commands) 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.

    3.3.1 Private messages

          Command: PRIVMSG
       Parameters: <msgtarget> <text to be sent>

       PRIVMSG is used to send private messages between users, as well as to
       send messages to channels.  <msgtarget> is usually the nickname of
       the recipient of the message, or a channel name.

       The <msgtarget> parameter may also be 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.  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!wings@irc.org PRIVMSG Wiz :Are you receiving this message ?
                                       ; Message from Angel to Wiz.

       PRIVMSG Angel :yes I'm receiving it !
                                       ; Command to send a message to Angel.

       PRIVMSG jto@tolsun.oulu.fi :Hello !
                                       ; Command to send a message to a user
                                       on server tolsun.oulu.fi with
                                       username of "jto".

       PRIVMSG kalt%millennium.stealth.net@irc.stealth.net :Are you a frog?
                                       ; Message to a user on server
                                       irc.stealth.net with username of
                                       "kalt", and connected from the host
                                       millennium.stealth.net.

       PRIVMSG kalt%millennium.stealth.net :Do you like cheese?
                                       ; Message to a user on the local
                                       server with username of "kalt", and
                                       connected from the host
                                       millennium.stealth.net.

       PRIVMSG Wiz!jto@tolsun.oulu.fi :Hello !
                                       ; Message to the user with nickname
                                       Wiz who is connected from the host
                                       tolsun.oulu.fi and has the username
                                       "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.

    3.3.2 Notice

          Command: NOTICE
       Parameters: <msgtarget> <text>

       The NOTICE command 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 clients automatically sending something in response to
       something it received.

       This command is available to services as well as users.

       This is typically used by services, and automatons (clients with
       either an AI or other interactive program controlling their actions).

       See PRIVMSG for more details on replies and examples.

    3.4 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.

       In these queries, where a parameter appears as <target>, wildcard
       masks are usually valid.  For each parameter, however, only one query
       and set of replies is to be generated.  In most cases, if a nickname
       is given, it will mean the server to which the user is connected.

       These messages typically have little value for services, it is
       therefore RECOMMENDED to forbid services from using them.

    3.4.1 Motd message

          Command: MOTD
       Parameters: [ <target> ]

       The MOTD command is used to get the "Message Of The Day" of the given
       server, or current server if <target> is omitted.

       Wildcards are allowed in the <target> parameter.

       Numeric Replies:
               RPL_MOTDSTART                   RPL_MOTD
               RPL_ENDOFMOTD                   ERR_NOMOTD

    3.4.2 Lusers message

          Command: LUSERS
       Parameters: [ <mask> [ <target> ] ]

       The LUSERS command is used to get statistics about the size of the
       IRC network.  If no parameter is given, the reply will be about the
       whole net.  If a <mask> is specified, then the reply will only

       concern the part of the network formed by the servers matching the
       mask.  Finally, if the <target> parameter is specified, the request
       is forwarded to that server which will generate the reply.

       Wildcards are allowed in the <target> parameter.

       Numeric Replies:

               RPL_LUSERCLIENT                 RPL_LUSEROP
               RPL_LUSERUNKOWN                 RPL_LUSERCHANNELS
               RPL_LUSERME                     ERR_NOSUCHSERVER

    3.4.3 Version message

          Command: VERSION
       Parameters: [ <target> ]

       The VERSION command is used to query the version of the server
       program.  An optional parameter <target> is used to query the version
       of the server program which a client is not directly connected to.

       Wildcards are allowed in the <target> parameter.

       Numeric Replies:

               ERR_NOSUCHSERVER                RPL_VERSION

       Examples:

       VERSION tolsun.oulu.fi          ; Command to check the version of
                                       server "tolsun.oulu.fi".

    3.4.4 Stats message

          Command: STATS
       Parameters: [ <query> [ <target> ] ]

       The stats command is used to query statistics of certain server.  If
       <query> parameter is omitted, only the end of stats reply is sent
       back.

       A query may be given for any single letter which is only checked by
       the destination server and is otherwise passed on by intermediate
       servers, ignored and unaltered.

       Wildcards are allowed in the <target> parameter.

       Except for the ones below, the list of valid queries is
       implementation dependent.  The standard queries below SHOULD be
       supported by the server:

                l - returns a list of the server's connections, showing how
                    long each connection has been established and the
                    traffic over that connection in Kbytes and messages for
                    each direction;
                m - returns the usage count for each of commands supported
                    by the server; commands for which the usage count is
                    zero MAY be omitted;
                o - returns a list of configured privileged users,
                    operators;
                u - returns a string showing how long the server has been
                    up.

       It is also RECOMMENDED that client and server access configuration be
       published this way.

       Numeric Replies:

               ERR_NOSUCHSERVER
               RPL_STATSLINKINFO                RPL_STATSUPTIME
               RPL_STATSCOMMANDS                RPL_STATSOLINE
               RPL_ENDOFSTATS

       Examples:

       STATS m                         ; Command to check the command usage
                                       for the server you are connected to

    3.4.5 Links message

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

       With LINKS, a user can list all servernames, 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:

       LINKS *.au                      ; Command to list all servers which
                                       have a name that matches *.au;

       LINKS *.edu *.bu.edu            ; Command to list servers matching
                                       *.bu.edu as seen by the first server
                                       matching *.edu.

    3.4.6 Time message

          Command: TIME
       Parameters: [ <target> ]

       The time command is used to query local time from the specified
       server. If the <target> parameter is not given, the server receiving
       the command must reply to the query.

       Wildcards are allowed in the <target> parameter.

       Numeric Replies:

               ERR_NOSUCHSERVER              RPL_TIME

       Examples:
       TIME tolsun.oulu.fi             ; check the time on the server
                                       "tolson.oulu.fi"

    3.4.7 Connect message

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

       The CONNECT command can be used to request a server to try to
       establish a new connection to another server immediately.  CONNECT is
       a privileged command and SHOULD be available only to IRC Operators.
       If a <remote server> is given and its mask doesn't match name of the
       parsing server, the CONNECT attempt is sent to the first match of
       remote server. Otherwise the CONNECT attempt is made by the server
       processing the request.

       The server receiving a remote CONNECT command SHOULD generate a
       WALLOPS message describing the source and target of the request.

       Numeric Replies:

               ERR_NOSUCHSERVER              ERR_NOPRIVILEGES
               ERR_NEEDMOREPARAMS

       Examples:

       CONNECT tolsun.oulu.fi 6667     ; Command to attempt to connect local
                                       server to tolsun.oulu.fi on port 6667

    3.4.8 Trace message

          Command: TRACE
       Parameters: [ <target> ]

       TRACE command is used to find the route to specific server and
       information about its peers.  Each server that processes this command
       MUST report to the sender about it.  The replies from pass-through
       links form a chain, which shows route to destination.  After sending
       this reply back, the query MUST be sent to the next server until
       given <target> server is reached.

       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.  After sending this reply back, it MUST then send the
       TRACE message to the next server until given server is reached.  If
       the <target> parameter is omitted, it is RECOMMENDED that TRACE
       command sends a message to the sender telling which servers the local
       server has direct connection to.

       If the destination given by <target> is an actual server, the
       destination server is REQUIRED to report all servers, services and
       operators which are connected to it; if the command was issued by an
       operator, the server MAY also report all users which are connected to
       it.  If the destination given by <target> is a nickname, then only a
       reply for that nickname is given.  If the <target> parameter is
       omitted, it is RECOMMENDED that the TRACE command is parsed as
       targeted to the processing server.

       Wildcards are allowed in the <target> parameter.

       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 it is 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                RPL_TRACELOG
               RPL_TRACEEND

       Examples:

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

    3.4.9 Admin command

          Command: ADMIN
       Parameters: [ <target> ]

       The admin command is used to find information about the administrator
       of the given server, or current server if <target> parameter is
       omitted.  Each server MUST have the ability to forward ADMIN messages
       to other servers.

       Wildcards are allowed in the <target> parameter.

       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

       ADMIN syrk                      ; ADMIN request for the server to
                                       which the user syrk is connected

    3.4.10 Info command

          Command: INFO
       Parameters: [ <target> ]

       The INFO command is REQUIRED to return information describing 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.

       Wildcards are allowed in the <target> parameter.

       Numeric Replies:

               ERR_NOSUCHSERVER
               RPL_INFO                      RPL_ENDOFINFO

       Examples:

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

       INFO Angel                      ; request info from the server that
                                       Angel is connected to.

    3.5 Service Query and Commands

       The service query group of commands has been designed to return
       information about any service which is connected to the network.

    3.5.1 Servlist message

          Command: SERVLIST
       Parameters: [ <mask> [ <type> ] ]

       The SERVLIST command is used to list services currently connected to
       the network and visible to the user issuing the command.  The
       optional parameters may be used to restrict the result of the query
       (to matching services names, and services type).

       Numeric Replies:

               RPL_SERVLIST                  RPL_SERVLISTEND

    3.5.2 Squery

          Command: SQUERY
       Parameters: <servicename> <text>

       The SQUERY command is used similarly to PRIVMSG.  The only difference
       is that the recipient MUST be a service.  This is the only way for a
       text message to be delivered to a service.

       See PRIVMSG for more details on replies and example.

       Examples:

       SQUERY irchelp :HELP privmsg
                                       ; Message to the service with
                                       nickname irchelp.

       SQUERY dict@irc.fr :fr2en blaireau
                                       ; Message to the service with name
                                       dict@irc.fr.

    3.6 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.

       Although services SHOULD NOT be using this class of message, they are
       allowed to.

    3.6.1 Who query

          Command: WHO
       Parameters: [ <mask> [ "o" ] ]

       The WHO command is used by a client to generate a query which returns
       a list of information which 'matches' the <mask> parameter given by
       the client.  In the absence of the <mask> 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 <mask> of "0" or any wildcard which
       will end up matching every visible user.

       The <mask> passed to WHO is matched against users' host, server, real
       name and nickname if the channel <mask> cannot be found.

       If the "o" parameter is passed only operators are returned according
       to the <mask> supplied.

       Numeric Replies:

               ERR_NOSUCHSERVER
               RPL_WHOREPLY                  RPL_ENDOFWHO

       Examples:

       WHO *.fi                        ; Command to list all users who match
                                       against "*.fi".

       WHO jto* o                      ; Command to list all users with a
                                       match against "jto*" if they are an
                                       operator.

    3.6.2 Whois query

          Command: WHOIS
       Parameters: [ <target> ] <mask> *( "," <mask> )

       This command is used to query information about particular user.
       The server will answer this command with several numeric messages
       indicating different statuses of each user which matches the mask (if
       you are entitled to see them).  If no wildcard is present in the
       <mask>, any information about that nick which you are allowed to see
       is presented.

       If the <target> parameter is specified, it 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 (i.e., the server the
       user is directly connected to) knows that information, while
       everything else is globally known.

       Wildcards are allowed in the <target> parameter.

       Numeric Replies:

               ERR_NOSUCHSERVER              ERR_NONICKNAMEGIVEN
               RPL_WHOISUSER                 RPL_WHOISCHANNELS
               RPL_WHOISCHANNELS             RPL_WHOISSERVER
               RPL_AWAY                      RPL_WHOISOPERATOR
               RPL_WHOISIDLE                 ERR_NOSUCHNICK
               RPL_ENDOFWHOIS

       Examples:

       WHOIS wiz                       ; return available user information
                                       about nick WiZ

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

    3.6.3 Whowas

          Command: WHOWAS
       Parameters: <nickname> *( "," <nickname> ) [ <count> [ <target> ] ]

       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.

       Wildcards are allowed in the <target> parameter.

       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".

    3.7 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.

    3.7.1 Kill message

          Command: KILL
       Parameters: <nickname> <comment>

       The KILL command is used to cause a client-server connection to be
       closed by the server which has the actual connection.  Servers
       generate KILL messages on nickname collisions.  It MAY also be
       available available to users who have the operator status.

       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 'flooding' from abusive users or accidents.  Abusive users usually
       don't care as they will reconnect promptly and resume their abusive
       behaviour.  To prevent this command from 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.

       When a client is removed as the result of a KILL message, the server
       SHOULD add the nickname to the list of unavailable nicknames in an
       attempt to avoid clients to reuse this name immediately which is
       usually the pattern of abusive behaviour often leading to useless
       "KILL loops".  See the "IRC Server Protocol" document [IRC-SERVER]
       for more information on this procedure.

       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

       NOTE:
       It is RECOMMENDED that only Operators be allowed to kill other users
       with KILL command.  This command has been the subject of many
       controversies over the years, and along with the above
       recommendation, it is also widely recognized that not even operators
       should be allowed to kill users on remote servers.

    3.7.2 Ping message

          Command: PING
       Parameters: <server1> [ <server2> ]

       The PING command is used to test the presence of an active client or
       server at the other end of the connection.  Servers send a PING
       message at regular intervals if no other activity detected coming
       from a connection.  If a connection fails to respond to a PING
       message within a set amount of time, that connection is closed.  A
       PING message MAY be sent even if the connection is active.

       When a PING message is received, the appropriate PONG message MUST be
       sent as reply to <server1> (server which sent the PING message out)
       as soon as possible.  If the <server2> parameter is specified, it
       represents the target of the ping, and the message gets forwarded
       there.

       Numeric Replies:

               ERR_NOORIGIN                  ERR_NOSUCHSERVER

       Examples:

       PING tolsun.oulu.fi             ; Command to send a PING message to
                                       server

       PING WiZ tolsun.oulu.fi         ; Command from WiZ to send a PING
                                       message to server "tolsun.oulu.fi"

       PING :irc.funet.fi              ; Ping message sent by server
                                       "irc.funet.fi"

    3.7.3 Pong message

          Command: PONG
       Parameters: <server> [ <server2> ]

       PONG message is a reply to ping message.  If parameter <server2> is
       given, this message MUST be forwarded to given target.  The <server>
       parameter is the name of the entity who has responded to PING message
       and generated this message.

       Numeric Replies:

               ERR_NOORIGIN                  ERR_NOSUCHSERVER

       Example:

       PONG csd.bu.edu tolsun.oulu.fi  ; PONG message from csd.bu.edu to
                                       tolsun.oulu.fi

    3.7.4 Error

          Command: ERROR
       Parameters: <error message>

       The ERROR command is for use by servers when reporting a serious or
       fatal error to its peers.  It may also be sent from one server to
       another but MUST NOT be accepted from any normal unknown clients.

       Only an ERROR message SHOULD be used for reporting errors which occur
       with a server-to-server link.  An ERROR message is sent to the server
       at the other end (which reports it to appropriate local users and
       logs) and to appropriate local users and logs.  It is not to be
       passed onto any other servers by a server if it is received from a
       server.

       The ERROR message is also used before terminating a client
       connection.

       When a server sends a received ERROR message to its operators, the
       message SHOULD be encapsulated inside a NOTICE message, indicating
       that the client was not responsible for the error.

       Numerics:

               None.

       Examples:

       ERROR :Server *.fi already exists ; ERROR message to the other server
                                       which caused this error.

       NOTICE WiZ :ERROR from csd.bu.edu -- Server *.fi already exists
                                       ; Same ERROR message as above but
                                       sent to user WiZ on the other server.

    4. Optional features

       This section describes OPTIONAL messages.  They are not required in a
       working server implementation of the protocol described herein.  In
       the absence of the feature, an error reply message MUST be generated
       or an unknown command error.  If the message is destined for another
       server to answer then it MUST be passed on (elementary parsing
       REQUIRED) The allocated numerics for this are listed with the
       messages below.

       From this section, only the USERHOST and ISON messages are available
       to services.

    4.1 Away

          Command: AWAY
       Parameters: [ <text> ]

       With the AWAY command, clients can set an automatic reply string for
       any PRIVMSG commands directed at them (not to a channel they are on).
       The server sends an automatic reply to the client sending the PRIVMSG
       command.  The only replying server is the one to which the sending
       client is connected to.

       The AWAY command is used either with one parameter, to set an AWAY
       message, or with no parameters, to remove the AWAY message.

       Because of its high cost (memory and bandwidth wise), the AWAY
       message SHOULD only be used for client-server communication.  A
       server MAY choose to silently ignore AWAY messages received from
       other servers.  To update the away status of a client across servers,
       the user mode 'a' SHOULD be used instead.  (See Section 3.1.5)

       Numeric Replies:

               RPL_UNAWAY                    RPL_NOWAWAY

       Example:

       AWAY :Gone to lunch.  Back in 5 ; Command to set away message to
                                       "Gone to lunch.  Back in 5".

    4.2 Rehash message

          Command: REHASH
       Parameters: None

       The rehash command is an administrative command which can be used by
       an operator to force the server to re-read and process its
       configuration file.

       Numeric Replies:

               RPL_REHASHING                 ERR_NOPRIVILEGES

       Example:

       REHASH                          ; message from user with operator
                                       status to server asking it to reread
                                       its configuration file.

    4.3 Die message

          Command: DIE
       Parameters: None

       An operator can use the DIE command to shutdown the server.  This
       message is optional since it may be viewed as a risk to allow
       arbitrary people to connect to a server as an operator and execute
       this command.

       The DIE command MUST always be fully processed by the server to which
       the sending client is connected and MUST NOT be passed onto other
       connected servers.

       Numeric Replies:

               ERR_NOPRIVILEGES

       Example:

       DIE                             ; no parameters required.

    4.4 Restart message

          Command: RESTART
       Parameters: None

       An operator can use the restart command to force the server to
       restart itself.  This message is optional since it may be viewed as a
       risk to allow arbitrary people to connect to a server as an operator
       and execute this command, causing (at least) a disruption to service.

       The RESTART command MUST always be fully processed by the server to
       which the sending client is connected and MUST NOT be passed onto
       other connected servers.

       Numeric Replies:

               ERR_NOPRIVILEGES

       Example:

       RESTART                         ; no parameters required.

    4.5 Summon message

          Command: SUMMON
       Parameters: <user> [ <target> [ <channel> ] ]

       The SUMMON command can be used to give users who are on a host
       running an IRC server a message asking them to please join IRC.  This
       message is only sent if the target server (a) has SUMMON enabled, (b)
       the user is logged in and (c) the server process can write to the
       user's tty (or similar).

       If no <server> parameter is given it tries to summon <user> from the
       server the client is connected to is assumed as the target.

       If summon is not enabled in a server, it MUST return the
       ERR_SUMMONDISABLED numeric.

       Numeric Replies:

               ERR_NORECIPIENT               ERR_FILEERROR
               ERR_NOLOGIN                   ERR_NOSUCHSERVER
               ERR_SUMMONDISABLED            RPL_SUMMONING

       Examples:

       SUMMON jto                      ; summon user jto on the server's
                                       host

       SUMMON jto tolsun.oulu.fi       ; summon user jto on the host which a
                                       server named "tolsun.oulu.fi" is
                                       running.

    4.6 Users

          Command: USERS
       Parameters: [ <target> ]

       The USERS command returns a list of users logged into the server in a
       format similar to the UNIX commands who(1), rusers(1) and finger(1).
       If disabled, the correct numeric MUST be returned to indicate this.

       Because of the security implications of such a command, it SHOULD be
       disabled by default in server implementations.  Enabling it SHOULD
       require recompiling the server or some equivalent change rather than
       simply toggling an option and restarting the server.  The procedure
       to enable this command SHOULD also include suitable large comments.

       Numeric Replies:

               ERR_NOSUCHSERVER              ERR_FILEERROR
               RPL_USERSSTART                RPL_USERS
               RPL_NOUSERS                   RPL_ENDOFUSERS
               ERR_USERSDISABLED

       Disabled Reply:

               ERR_USERSDISABLED

       Example:

       USERS eff.org                   ; request a list of users logged in
                                       on server eff.org

    4.7 Operwall message

          Command: WALLOPS
       Parameters: <Text to be sent>

       The WALLOPS command is used to send a message to all currently
       connected users who have set the 'w' user mode for themselves.  (See
       Section 3.1.5 "User modes").

       After implementing WALLOPS as a user command it was found that it was
       often and commonly abused as a means of sending a message to a lot of
       people.  Due to this, it is RECOMMENDED that the implementation of
       WALLOPS allows and recognizes only servers as the originators of
       WALLOPS.

       Numeric Replies:

               ERR_NEEDMOREPARAMS

       Example:

       :csd.bu.edu WALLOPS :Connect '*.uiuc.edu 6667' from Joshua ; WALLOPS
                                       message from csd.bu.edu announcing a
                                       CONNECT message it received from
                                       Joshua and acted upon.

    4.8 Userhost message

          Command: USERHOST
       Parameters: <nickname> *( SPACE <nickname> )

       The USERHOST command takes a list of up to 5 nicknames, each
       separated by a space character and returns a list of information
       about each nickname that it found.  The returned list has each reply
       separated by a space.

       Numeric Replies:

               RPL_USERHOST                  ERR_NEEDMOREPARAMS

       Example:

       USERHOST Wiz Michael syrk       ; USERHOST request for information on
                                       nicks "Wiz", "Michael", and "syrk"

       :ircd.stealth.net 302 yournick :syrk=+syrk@millennium.stealth.net
                                       ; Reply for user syrk

    4.9 Ison message

          Command: ISON
       Parameters: <nickname> *( SPACE <nickname> )

       The ISON command was implemented to provide a quick and efficient
       means to get a response about whether a given nickname was currently
       on IRC. ISON only takes one (1) type of parameter: a space-separated
       list of nicks.  For each nickname in the list that is present, the

       server adds that to its reply string.  Thus the reply string may
       return empty (none of the given nicks are present), an exact copy of
       the parameter string (all of them present) or any other subset of the
       set of nicks given in the parameter.  The only limit on the number of
       nicks that may be checked is that the combined length MUST NOT be too
       large as to cause the server to chop it off so it fits in 512
       characters.

       ISON is only processed by the server local to the client sending the
       command and thus not passed onto other servers for further
       processing.

       Numeric Replies:

               RPL_ISON                      ERR_NEEDMOREPARAMS

       Example:

       ISON phone trillian WiZ jarlek Avalon Angel Monstah syrk
                                       ; Sample ISON request for 7 nicks.

    5. Replies

       The following is a list of numeric replies which are generated in
       response to the commands given above.  Each numeric is given with its
       number, name and reply string.

    5.1 Command responses

       Numerics in the range from 001 to 099 are used for client-server
       connections only and should never travel between servers.  Replies
       generated in the response to commands are found in the range from 200
       to 399.

           001    RPL_WELCOME
                  "Welcome to the Internet Relay Network
                   <nick>!<user>@<host>"
           002    RPL_YOURHOST
                  "Your host is <servername>, running version <ver>"
           003    RPL_CREATED
                  "This server was created <date>"
           004    RPL_MYINFO
                  "<servername> <version> <available user modes>
                   <available channel modes>"

             - The server sends Replies 001 to 004 to a user upon
               successful registration.

           005    RPL_BOUNCE
                  "Try server <server name>, port <port number>"

             - Sent by the server to a user to suggest an alternative
               server.  This is often used when the connection is
               refused because the server is already full.

           302    RPL_USERHOST
                  ":*1<reply> *( " " <reply> )"

             - Reply format used by USERHOST to list replies to
               the query list.  The reply string is composed as
               follows:

               reply = nickname [ "*" ] "=" ( "+" / "-" ) hostname

               The '*' indicates whether the client has registered
               as an Operator.  The '-' or '+' characters represent
               whether the client has set an AWAY message or not
               respectively.

           303    RPL_ISON
                  ":*1<nick> *( " " <nick> )"

             - Reply format used by ISON to list replies to the
               query list.

           301    RPL_AWAY
                  "<nick> :<away message>"
           305    RPL_UNAWAY
                  ":You are no longer marked as being away"
           306    RPL_NOWAWAY
                  ":You have been marked as being away"

             - These replies are used with the AWAY command (if
               allowed).  RPL_AWAY is sent to any client sending a
               PRIVMSG to a client which is away.  RPL_AWAY is only
               sent by the server to which the client is connected.
               Replies RPL_UNAWAY and RPL_NOWAWAY are sent when the
               client removes and sets an AWAY message.

           311    RPL_WHOISUSER
                  "<nick> <user> <host> * :<real name>"
           312    RPL_WHOISSERVER
                  "<nick> <server> :<server info>"
           313    RPL_WHOISOPERATOR
                  "<nick> :is an IRC operator"

           317    RPL_WHOISIDLE
                  "<nick> <integer> :seconds idle"
           318    RPL_ENDOFWHOIS
                  "<nick> :End of WHOIS list"
           319    RPL_WHOISCHANNELS
                  "<nick> :*( ( "@" / "+" ) <channel> " " )"

             - Replies 311 - 313, 317 - 319 are all replies
               generated in response to a WHOIS message.  Given that
               there are enough parameters present, the answering
               server MUST either formulate a reply out of the above
               numerics (if the query nick is found) or return an
               error reply.  The '*' in RPL_WHOISUSER is there as
               the literal character and not as a wild card.  For
               each reply set, only RPL_WHOISCHANNELS may appear
               more than once (for long lists of channel names).
               The '@' and '+' characters next to the channel name
               indicate whether a client is a channel operator or
               has been granted permission to speak on a moderated
               channel.  The RPL_ENDOFWHOIS reply is used to mark
               the end of processing a WHOIS message.

           314    RPL_WHOWASUSER
                  "<nick> <user> <host> * :<real name>"
           369    RPL_ENDOFWHOWAS
                  "<nick> :End of WHOWAS"

             - When replying to a WHOWAS message, a server MUST use
               the replies RPL_WHOWASUSER, RPL_WHOISSERVER or
               ERR_WASNOSUCHNICK for each nickname in the presented
               list.  At the end of all reply batches, there MUST
               be RPL_ENDOFWHOWAS (even if there was only one reply
               and it was an error).

           321    RPL_LISTSTART
                  Obsolete. Not used.

           322    RPL_LIST
                  "<channel> <# visible> :<topic>"
           323    RPL_LISTEND
                  ":End of LIST"

             - Replies RPL_LIST, RPL_LISTEND mark the actual replies
               with data and end of the server's response to a LIST
               command.  If there are no channels available to return,
               only the end reply MUST be sent.

           325    RPL_UNIQOPIS
                  "<channel> <nickname>"

           324    RPL_CHANNELMODEIS
                  "<channel> <mode> <mode params>"

           331    RPL_NOTOPIC
                  "<channel> :No topic is set"
           332    RPL_TOPIC
                  "<channel> :<topic>"

             - When sending a TOPIC message to determine the
               channel topic, one of two replies is sent.  If
               the topic is set, RPL_TOPIC is sent back else
               RPL_NOTOPIC.

           341    RPL_INVITING
                  "<channel> <nick>"

             - Returned by the server to indicate that the
               attempted INVITE message was successful and is
               being passed onto the end client.

           342    RPL_SUMMONING
                  "<user> :Summoning user to IRC"

             - Returned by a server answering a SUMMON message to
               indicate that it is summoning that user.

           346    RPL_INVITELIST
                  "<channel> <invitemask>"
           347    RPL_ENDOFINVITELIST
                  "<channel> :End of channel invite list"

             - When listing the 'invitations masks' for a given channel,
               a server is required to send the list back using the
               RPL_INVITELIST and RPL_ENDOFINVITELIST messages.  A
               separate RPL_INVITELIST is sent for each active mask.
               After the masks have been listed (or if none present) a
               RPL_ENDOFINVITELIST MUST be sent.

           348    RPL_EXCEPTLIST
                  "<channel> <exceptionmask>"
           349    RPL_ENDOFEXCEPTLIST
                  "<channel> :End of channel exception list"

             - When listing the 'exception masks' for a given channel,
               a server is required to send the list back using the
               RPL_EXCEPTLIST and RPL_ENDOFEXCEPTLIST messages.  A
               separate RPL_EXCEPTLIST is sent for each active mask.
               After the masks have been listed (or if none present)
               a RPL_ENDOFEXCEPTLIST MUST be sent.

           351    RPL_VERSION
                  "<version>.<debuglevel> <server> :<comments>"

             - Reply by the server showing its version details.
               The <version> is the version of the software being
               used (including any patchlevel revisions) and the
               <debuglevel> is used to indicate if the server is
               running in "debug mode".

               The "comments" field may contain any comments about
               the version or further version details.

           352    RPL_WHOREPLY
                  "<channel> <user> <host> <server> <nick>
                  ( "H" / "G" > ["*"] [ ( "@" / "+" ) ]
                  :<hopcount> <real name>"

           315    RPL_ENDOFWHO
                  "<name> :End of WHO list"

             - The RPL_WHOREPLY and RPL_ENDOFWHO pair are used
               to answer a WHO message.  The RPL_WHOREPLY is only
               sent if there is an appropriate match to the WHO
               query.  If there is a list of parameters supplied
               with a WHO message, a RPL_ENDOFWHO MUST be sent
               after processing each list item with <name> being
               the item.

           353    RPL_NAMREPLY
                  "( "=" / "*" / "@" ) <channel>
                   :[ "@" / "+" ] <nick> *( " " [ "@" / "+" ] <nick> )
             - "@" is used for secret channels, "*" for private
               channels, and "=" for others (public channels).

           366    RPL_ENDOFNAMES
                  "<channel> :End of NAMES list"

             - To reply to a NAMES message, a reply pair consisting
               of RPL_NAMREPLY and RPL_ENDOFNAMES is sent by the
               server back to the client.  If there is no channel
               found as in the query, then only RPL_ENDOFNAMES is

               returned.  The exception to this is when a NAMES
               message is sent with no parameters and all visible
               channels and contents are sent back in a series of
               RPL_NAMEREPLY messages with a RPL_ENDOFNAMES to mark
               the end.

           364    RPL_LINKS
                  "<mask> <server> :<hopcount> <server info>"
           365    RPL_ENDOFLINKS
                  "<mask> :End of LINKS list"

             - In replying to the LINKS message, a server MUST send
               replies back using the RPL_LINKS numeric and mark the
               end of the list using an RPL_ENDOFLINKS reply.

           367    RPL_BANLIST
                  "<channel> <banmask>"
           368    RPL_ENDOFBANLIST
                  "<channel> :End of channel ban list"

             - When listing the active 'bans' for a given channel,
               a server is required to send the list back using the
               RPL_BANLIST and RPL_ENDOFBANLIST messages.  A separate
               RPL_BANLIST is sent for each active banmask.  After the
               banmasks have been listed (or if none present) a
               RPL_ENDOFBANLIST MUST be sent.

           371    RPL_INFO
                  ":<string>"
           374    RPL_ENDOFINFO
                  ":End of INFO list"

             - A server responding to an INFO message is required to
               send all its 'info' in a series of RPL_INFO messages
               with a RPL_ENDOFINFO reply to indicate the end of the
               replies.

           375    RPL_MOTDSTART
                  ":- <server> Message of the day - "
           372    RPL_MOTD
                  ":- <text>"
           376    RPL_ENDOFMOTD
                  ":End of MOTD command"

             - When responding to the MOTD message and the MOTD file
               is found, the file is displayed line by line, with
               each line no longer than 80 characters, using

               RPL_MOTD format replies.  These MUST be surrounded
               by a RPL_MOTDSTART (before the RPL_MOTDs) and an
               RPL_ENDOFMOTD (after).

           381    RPL_YOUREOPER
                  ":You are now an IRC operator"

             - RPL_YOUREOPER is sent back to a client which has
               just successfully issued an OPER message and gained
               operator status.

           382    RPL_REHASHING
                  "<config file> :Rehashing"

             - If the REHASH option is used and an operator sends
               a REHASH message, an RPL_REHASHING is sent back to
               the operator.

           383    RPL_YOURESERVICE
                  "You are service <servicename>"

             - Sent by the server to a service upon successful
               registration.

           391    RPL_TIME
                  "<server> :<string showing server's local time>"

             - When replying to the TIME message, a server MUST send
               the reply using the RPL_TIME format above.  The string
               showing the time need only contain the correct day and
               time there.  There is no further requirement for the
               time string.

           392    RPL_USERSSTART
                  ":UserID   Terminal  Host"
           393    RPL_USERS
                  ":<username> <ttyline> <hostname>"
           394    RPL_ENDOFUSERS
                  ":End of users"
           395    RPL_NOUSERS
                  ":Nobody logged in"

             - If the USERS message is handled by a server, the
               replies RPL_USERSTART, RPL_USERS, RPL_ENDOFUSERS and
               RPL_NOUSERS are used.  RPL_USERSSTART MUST be sent
               first, following by either a sequence of RPL_USERS
               or a single RPL_NOUSER.  Following this is
               RPL_ENDOFUSERS.

           200    RPL_TRACELINK
                  "Link <version & debug level> <destination>
                   <next server> V<protocol version>
                   <link uptime in seconds> <backstream sendq>
                   <upstream sendq>"
           201    RPL_TRACECONNECTING
                  "Try. <class> <server>"
           202    RPL_TRACEHANDSHAKE
                  "H.S. <class> <server>"
           203    RPL_TRACEUNKNOWN
                  "???? <class> [<client IP address in dot form>]"
           204    RPL_TRACEOPERATOR
                  "Oper <class> <nick>"
           205    RPL_TRACEUSER
                  "User <class> <nick>"
           206    RPL_TRACESERVER
                  "Serv <class> <int>S <int>C <server>
                   <nick!user|*!*>@<host|server> V<protocol version>"
           207    RPL_TRACESERVICE
                  "Service <class> <name> <type> <active type>"
           208    RPL_TRACENEWTYPE
                  "<newtype> 0 <client name>"
           209    RPL_TRACECLASS
                  "Class <class> <count>"
           210    RPL_TRACERECONNECT
                  Unused.
           261    RPL_TRACELOG
                  "File <logfile> <debug level>"
           262    RPL_TRACEEND
                  "<server name> <version & debug level> :End of TRACE"

             - The RPL_TRACE* are all returned by the server in
               response to the TRACE message.  How many are
               returned is dependent on the TRACE message and
               whether it was sent by an operator or not.  There
               is no predefined order for which occurs first.
               Replies RPL_TRACEUNKNOWN, RPL_TRACECONNECTING and
               RPL_TRACEHANDSHAKE are all used for connections
               which have not been fully established and are either
               unknown, still attempting to connect or in the
               process of completing the 'server handshake'.
               RPL_TRACELINK is sent by any server which handles
               a TRACE message and has to pass it on to another
               server.  The list of RPL_TRACELINKs sent in
               response to a TRACE command traversing the IRC
               network should reflect the actual connectivity of
               the servers themselves along that path.

               RPL_TRACENEWTYPE is to be used for any connection
               which does not fit in the other categories but is
               being displayed anyway.
               RPL_TRACEEND is sent to indicate the end of the list.

           211    RPL_STATSLINKINFO
                  "<linkname> <sendq> <sent messages>
                   <sent Kbytes> <received messages>
                   <received Kbytes> <time open>"

             - reports statistics on a connection.  <linkname>
               identifies the particular connection, <sendq> is
               the amount of data that is queued and waiting to be
               sent <sent messages> the number of messages sent,
               and <sent Kbytes> the amount of data sent, in
               Kbytes. <received messages> and <received Kbytes>
               are the equivalent of <sent messages> and <sent
               Kbytes> for received data, respectively.  <time
               open> indicates how long ago the connection was
               opened, in seconds.

           212    RPL_STATSCOMMANDS
                  "<command> <count> <byte count> <remote count>"

             - reports statistics on commands usage.

           219    RPL_ENDOFSTATS
                  "<stats letter> :End of STATS report"

           242    RPL_STATSUPTIME
                  ":Server Up %d days %d:%02d:%02d"

             - reports the server uptime.

           243    RPL_STATSOLINE
                  "O <hostmask> * <name>"

             - reports the allowed hosts from where user may become IRC
               operators.

           221    RPL_UMODEIS
                  "<user mode string>"

             - To answer a query about a client's own mode,
               RPL_UMODEIS is sent back.

           234    RPL_SERVLIST
                  "<name> <server> <mask> <type> <hopcount> <info>"

           235    RPL_SERVLISTEND
                  "<mask> <type> :End of service listing"

             - When listing services in reply to a SERVLIST message,
               a server is required to send the list back using the
               RPL_SERVLIST and RPL_SERVLISTEND messages.  A separate
               RPL_SERVLIST is sent for each service.  After the
               services have been listed (or if none present) a
               RPL_SERVLISTEND MUST be sent.

           251    RPL_LUSERCLIENT
                  ":There are <integer> users and <integer>
                   services on <integer> servers"
           252    RPL_LUSEROP
                  "<integer> :operator(s) online"
           253    RPL_LUSERUNKNOWN
                  "<integer> :unknown connection(s)"
           254    RPL_LUSERCHANNELS
                  "<integer> :channels formed"
           255    RPL_LUSERME
                  ":I have <integer> clients and <integer>
                    servers"

             - In processing an LUSERS message, the server
               sends a set of replies from RPL_LUSERCLIENT,
               RPL_LUSEROP, RPL_USERUNKNOWN,
               RPL_LUSERCHANNELS and RPL_LUSERME.  When
               replying, a server MUST send back
               RPL_LUSERCLIENT and RPL_LUSERME.  The other
               replies are only sent back if a non-zero count
               is found for them.

           256    RPL_ADMINME
                  "<server> :Administrative info"
           257    RPL_ADMINLOC1
                  ":<admin info>"
           258    RPL_ADMINLOC2
                  ":<admin info>"
           259    RPL_ADMINEMAIL
                  ":<admin info>"

             - When replying to an ADMIN message, a server
               is expected to use replies RPL_ADMINME
               through to RPL_ADMINEMAIL and provide a text
               message with each.  For RPL_ADMINLOC1 a
               description of what city, state and country
               the server is in is expected, followed by
               details of the institution (RPL_ADMINLOC2)

               and finally the administrative contact for the
               server (an email address here is REQUIRED)
               in RPL_ADMINEMAIL.

           263    RPL_TRYAGAIN
                  "<command> :Please wait a while and try again."

             - When a server drops a command without processing it,
               it MUST use the reply RPL_TRYAGAIN to inform the
               originating client.

    5.2 Error Replies

           Error replies are found in the range from 400 to 599.

           401    ERR_NOSUCHNICK
                  "<nickname> :No such nick/channel"

              - Used to indicate the nickname parameter supplied to a
                command is currently unused.

           402    ERR_NOSUCHSERVER
                  "<server name> :No such server"

             - Used to indicate the server name given currently
               does not exist.

           403    ERR_NOSUCHCHANNEL
                  "<channel name> :No such channel"

             - Used to indicate the given channel name is invalid.

           404    ERR_CANNOTSENDTOCHAN
                  "<channel name> :Cannot send to channel"

             - Sent to a user who is either (a) not on a channel
               which is mode +n or (b) not a chanop (or mode +v) on
               a channel which has mode +m set or where the user is
               banned and is trying to send a PRIVMSG message to
               that channel.

           405    ERR_TOOMANYCHANNELS
                  "<channel name> :You have joined too many channels"

             - Sent to a user when they have joined the maximum
               number of allowed channels and they try to join
               another channel.

           406    ERR_WASNOSUCHNICK
                  "<nickname> :There was no such nickname"

             - Returned by WHOWAS to indicate there is no history
               information for that nickname.

           407    ERR_TOOMANYTARGETS
                  "<target> :<error code> recipients. <abort message>"

             - Returned to a client which is attempting to send a
               PRIVMSG/NOTICE using the user@host destination format
               and for a user@host which has several occurrences.

             - Returned to a client which trying to send a
               PRIVMSG/NOTICE to too many recipients.

             - Returned to a client which is attempting to JOIN a safe
               channel using the shortname when there are more than one
               such channel.

           408    ERR_NOSUCHSERVICE
                  "<service name> :No such service"

             - Returned to a client which is attempting to send a SQUERY
               to a service which does not exist.

           409    ERR_NOORIGIN
                  ":No origin specified"

             - PING or PONG message missing the originator parameter.

           411    ERR_NORECIPIENT
                  ":No recipient given (<command>)"
           412    ERR_NOTEXTTOSEND
                  ":No text to send"
           413    ERR_NOTOPLEVEL
                  "<mask> :No toplevel domain specified"
           414    ERR_WILDTOPLEVEL
                  "<mask> :Wildcard in toplevel domain"
           415    ERR_BADMASK
                  "<mask> :Bad Server/host mask"

             - 412 - 415 are returned by PRIVMSG to indicate that
               the message wasn't delivered for some reason.
               ERR_NOTOPLEVEL and ERR_WILDTOPLEVEL are errors that
               are returned when an invalid use of
               "PRIVMSG $<server>" or "PRIVMSG #<host>" is attempted.

           421    ERR_UNKNOWNCOMMAND
                  "<command> :Unknown command"

             - Returned to a registered client to indicate that the
               command sent is unknown by the server.

           422    ERR_NOMOTD
                  ":MOTD File is missing"

             - Server's MOTD file could not be opened by the server.

           423    ERR_NOADMININFO
                  "<server> :No administrative info available"

             - Returned by a server in response to an ADMIN message
               when there is an error in finding the appropriate
               information.

           424    ERR_FILEERROR
                  ":File error doing <file op> on <file>"

             - Generic error message used to report a failed file
               operation during the processing of a message.

           431    ERR_NONICKNAMEGIVEN
                  ":No nickname given"

             - Returned when a nickname parameter expected for a
               command and isn't found.

           432    ERR_ERRONEUSNICKNAME
                  "<nick> :Erroneous nickname"

             - Returned after receiving a NICK message which contains
               characters which do not fall in the defined set.  See
               section 2.3.1 for details on valid nicknames.

           433    ERR_NICKNAMEINUSE
                  "<nick> :Nickname is already in use"

             - Returned when a NICK message is processed that results
               in an attempt to change to a currently existing
               nickname.

           436    ERR_NICKCOLLISION
                  "<nick> :Nickname collision KILL from <user>@<host>"

             - Returned by a server to a client when it detects a
               nickname collision (registered of a NICK that
               already exists by another server).

           437    ERR_UNAVAILRESOURCE
                  "<nick/channel> :Nick/channel is temporarily unavailable"

             - Returned by a server to a user trying to join a channel
               currently blocked by the channel delay mechanism.

             - Returned by a server to a user trying to change nickname
               when the desired nickname is blocked by the nick delay
               mechanism.

           441    ERR_USERNOTINCHANNEL
                  "<nick> <channel> :They aren't on that channel"

             - Returned by the server to indicate that the target
               user of the command is not on the given channel.

           442    ERR_NOTONCHANNEL
                  "<channel> :You're not on that channel"

             - Returned by the server whenever a client tries to
               perform a channel affecting command for which the
               client isn't a member.

           443    ERR_USERONCHANNEL
                  "<user> <channel> :is already on channel"

             - Returned when a client tries to invite a user to a
               channel they are already on.

           444    ERR_NOLOGIN
                  "<user> :User not logged in"

             - Returned by the summon after a SUMMON command for a
               user was unable to be performed since they were not
               logged in.

           445    ERR_SUMMONDISABLED
                  ":SUMMON has been disabled"

             - Returned as a response to the SUMMON command.  MUST be
               returned by any server which doesn't implement it.

           446    ERR_USERSDISABLED
                  ":USERS has been disabled"

             - Returned as a response to the USERS command.  MUST be
               returned by any server which does not implement it.

           451    ERR_NOTREGISTERED
                  ":You have not registered"

             - Returned by the server to indicate that the client
               MUST be registered before the server will allow it
               to be parsed in detail.

           461    ERR_NEEDMOREPARAMS
                  "<command> :Not enough parameters"

             - Returned by the server by numerous commands to
               indicate to the client that it didn't supply enough
               parameters.

           462    ERR_ALREADYREGISTRED
                  ":Unauthorized command (already registered)"

             - Returned by the server to any link which tries to
               change part of the registered details (such as
               password or user details from second USER message).

           463    ERR_NOPERMFORHOST
                  ":Your host isn't among the privileged"

             - Returned to a client which attempts to register with
               a server which does not been setup to allow
               connections from the host the attempted connection
               is tried.

           464    ERR_PASSWDMISMATCH
                  ":Password incorrect"

             - Returned to indicate a failed attempt at registering
               a connection for which a password was required and
               was either not given or incorrect.

           465    ERR_YOUREBANNEDCREEP
                  ":You are banned from this server"

             - Returned after an attempt to connect and register
               yourself with a server which has been setup to
               explicitly deny connections to you.

           466    ERR_YOUWILLBEBANNED

             - Sent by a server to a user to inform that access to the
               server will soon be denied.

           467    ERR_KEYSET
                  "<channel> :Channel key already set"
           471    ERR_CHANNELISFULL
                  "<channel> :Cannot join channel (+l)"
           472    ERR_UNKNOWNMODE
                  "<char> :is unknown mode char to me for <channel>"
           473    ERR_INVITEONLYCHAN
                  "<channel> :Cannot join channel (+i)"
           474    ERR_BANNEDFROMCHAN
                  "<channel> :Cannot join channel (+b)"
           475    ERR_BADCHANNELKEY
                  "<channel> :Cannot join channel (+k)"
           476    ERR_BADCHANMASK
                  "<channel> :Bad Channel Mask"
           477    ERR_NOCHANMODES
                  "<channel> :Channel doesn't support modes"
           478    ERR_BANLISTFULL
                  "<channel> <char> :Channel list is full"

           481    ERR_NOPRIVILEGES
                  ":Permission Denied- You're not an IRC operator"

             - Any command requiring operator privileges to operate
               MUST return this error to indicate the attempt was
               unsuccessful.

           482    ERR_CHANOPRIVSNEEDED
                  "<channel> :You're not channel operator"

             - Any command requiring 'chanop' privileges (such as
               MODE messages) MUST return this error if the client
               making the attempt is not a chanop on the specified
               channel.

           483    ERR_CANTKILLSERVER
                  ":You can't kill a server!"

             - Any attempts to use the KILL command on a server
               are to be refused and this error returned directly
               to the client.

           484    ERR_RESTRICTED
                  ":Your connection is restricted!"

             - Sent by the server to a user upon connection to indicate
               the restricted nature of the connection (user mode "+r").

           485    ERR_UNIQOPPRIVSNEEDED
                  ":You're not the original channel operator"

             - Any MODE requiring "channel creator" privileges MUST
               return this error if the client making the attempt is not
               a chanop on the specified channel.

           491    ERR_NOOPERHOST
                  ":No O-lines for your host"

             - If a client sends an OPER message and the server has
               not been configured to allow connections from the
               client's host as an operator, this error MUST be
               returned.

           501    ERR_UMODEUNKNOWNFLAG
                  ":Unknown MODE flag"

             - Returned by the server to indicate that a MODE
               message was sent with a nickname parameter and that
               the a mode flag sent was not recognized.

           502    ERR_USERSDONTMATCH
                  ":Cannot change mode for other users"

             - Error sent to any user trying to view or change the
               user mode for a user other than themselves.

    5.3 Reserved numerics

       These numerics are not described above since they fall into one of
       the following categories:

       1. no longer in use;

       2. reserved for future planned use;

       3. in current use but are part of a non-generic 'feature' of
          the current IRC server.

                231    RPL_SERVICEINFO     232  RPL_ENDOFSERVICES
                233    RPL_SERVICE
                300    RPL_NONE            316  RPL_WHOISCHANOP
                361    RPL_KILLDONE        362  RPL_CLOSING
                363    RPL_CLOSEEND        373  RPL_INFOSTART
                384    RPL_MYPORTIS

                213    RPL_STATSCLINE      214  RPL_STATSNLINE
                215    RPL_STATSILINE      216  RPL_STATSKLINE
                217    RPL_STATSQLINE      218  RPL_STATSYLINE
                240    RPL_STATSVLINE      241  RPL_STATSLLINE
                244    RPL_STATSHLINE      244  RPL_STATSSLINE
                246    RPL_STATSPING       247  RPL_STATSBLINE
                250    RPL_STATSDLINE

                492    ERR_NOSERVICEHOST

    6. Current implementations

       The IRC software, version 2.10 is the only complete implementation of
       the IRC protocol (client and server).  Because of the small amount of
       changes in the client protocol since the publication of RFC 1459
       [IRC], implementations that follow it are likely to be compliant with
       this protocol or to require a small amount of changes to reach
       compliance.

    7. Current problems

       There are a number of recognized problems with the IRC Client
       Protocol, and more generally with the IRC Server Protocol.  In order
       to preserve backward compatibility with old clients, this protocol
       has almost not evolved since the publication of RFC 1459 [IRC].

    7.1 Nicknames

       The idea of the nickname on IRC is very convenient for users to use
       when talking to each other outside of a channel, but there is only a
       finite nickname space and being what they are, it's not uncommon for
       several people to want to use the same nick.  If a nickname is chosen
       by two people using this protocol, either one will not succeed or
       both will removed by use of a server KILL (See Section 3.7.1).

    7.2 Limitation of wildcards

       There is no way to escape the escape character "\" (%x5C).  While
       this isn't usually a problem, it makes it impossible to form a mask
       with a backslash character ("\") preceding a wildcard.

    7.3 Security considerations

       Security issues related to this protocol are discussed in the "IRC
       Server Protocol" [IRC-SERVER] as they are mostly an issue for the
       server side of the connection.

    8. Current support and availability

            Mailing lists for IRC related discussion:
              General discussion: ircd-users@irc.org
              Protocol development: ircd-dev@irc.org

            Software implementations:
              ftp://ftp.irc.org/irc/server
              ftp://ftp.funet.fi/pub/unix/irc
              ftp://ftp.irc.org/irc/clients

            Newsgroup: alt.irc

    9. Acknowledgements

       Parts of this document were copied from the RFC 1459 [IRC] which
       first formally documented the IRC Protocol.  It has also benefited
       from many rounds of review and comments.  In particular, the
       following people have made significant contributions to this
       document:

       Matthew Green, Michael Neumayer, Volker Paulsen, Kurt Roeckx, Vesa
       Ruokonen, Magnus Tjernstrom, Stefan Zehl.

    10. References

       [KEYWORDS]   Bradner, S., "Key words for use in RFCs to Indicate
                    Requirement Levels", BCP 14, RFC 2119, March 1997.

       [ABNF]       Crocker, D. and P. Overell, "Augmented BNF for Syntax
                    Specifications: ABNF", RFC 2234, November 1997.

       [HNAME]      Braden, R., "Requirements for Internet Hosts --
                    Application and Support", STD 3, RFC 1123, October 1989.

       [IRC]        Oikarinen, J. & D. Reed, "Internet Relay Chat Protocol",
                    RFC 1459, May 1993.

       [IRC-ARCH]   Kalt, C., "Internet Relay Chat: Architecture", RFC 2810,
                    April 2000.

       [IRC-CHAN]   Kalt, C., "Internet Relay Chat: Channel Management", RFC
                    2811, April 2000.

       [IRC-SERVER] Kalt, C., "Internet Relay Chat: Server Protocol", RFC
                    2813, April 2000.

    11. Author's Address

       Christophe Kalt
       99 Teaneck Rd, Apt #117
       Ridgefield Park, NJ 07660
       USA

       EMail: kalt@stealth.net

    12.  Full Copyright Statement

       Copyright (C) The Internet Society (2000).  All Rights Reserved.

       This document and translations of it may be copied and furnished to
       others, and derivative works that comment on or otherwise explain it
       or assist in its implementation may be prepared, copied, published
       and distributed, in whole or in part, without restriction of any
       kind, provided that the above copyright notice and this paragraph are
       included on all such copies and derivative works.  However, this
       document itself may not be modified in any way, such as by removing
       the copyright notice or references to the Internet Society or other
       Internet organizations, except as needed for the purpose of
       developing Internet standards in which case the procedures for
       copyrights defined in the Internet Standards process must be
       followed, or as required to translate it into languages other than
       English.

       The limited permissions granted above are perpetual and will not be
       revoked by the Internet Society or its successors or assigns.

       This document and the information contained herein is provided on an
       "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
       TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
       BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
       HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
       MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

    Acknowledgement

       Funding for the RFC Editor function is currently provided by the
       Internet Society.

Comments about this RFC: RFC 2812: Errata in BNF for "chanstring"? The definition for "chanstring" in section s... by SuD (5/7/2004)

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