# RFC2812

The IRC protocol specification (revised)

    Network Working Group, C.Kalt, April 2000
    Request for Comments: 2812
    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

- 1.1 Servers
- 1.2 Clients

- 1.2.1 Users

- 1.2.1.1 Operators

- 1.2.2 Services

- 1.3 Channels

- 2. The IRC Client Specification

- 2.1 Overview
- 2.2 Character codes
- 2.3 Messages

- 2.3.1 Message format in Augmented BNF

- 2.4 Numeric replies
- 2.5 Wildcard expressions

- 3. Message Details

- 3.1 Connection Registration

- 3.1.1 Password message
- 3.1.2 Nick message
- 3.1.3 User message
- 3.1.4 Oper message
- 3.1.5 User mode message
- 3.1.6 Service message
- 3.1.7 Quit
- 3.1.8 Squit

- 3.2 Channel operations

- 3.2.1 Join message
- 3.2.2 Part message
- 3.2.3 Channel mode message
- 3.2.4 Topic message
- 3.2.5 Names message
- 3.2.6 List message
- 3.2.7 Invite message
- 3.2.8 Kick command

- 3.3 Sending messages

- 3.3.1 Private messages
- 3.3.2 Notice

- 3.4 Server queries and commands

- 3.4.1 Motd message
- 3.4.2 Lusers message
- 3.4.3 Version message
- 3.4.4 Stats message
- 3.4.5 Links message
- 3.4.6 Time message
- 3.4.7 Connect message
- 3.4.8 Trace message
- 3.4.9 Admin command
- 3.4.10 Info command

- 3.5 Service Query and Commands

- 3.5.1 Servlist message
- 3.5.2 Squery

- 3.6 User based queries

- 3.6.1 Who query
- 3.6.2 Whois query
- 3.6.3 Whowas

- 3.7 Miscellaneous messages

- 3.7.1 Kill message
- 3.7.2 Ping message
- 3.7.3 Pong message
- 3.7.4 Error

- 4. Optional features

- 4.1 Away
- 4.2 Rehash message
- 4.3 Die message
- 4.4 Restart message
- 4.5 Summon message
- 4.6 Users
- 4.7 Operwall message
- 4.8 Userhost message
- 4.9 Ison message

- 5. Replies

- 5.1 Command responses
- 5.2 Error Replies
- 5.3 Reserved numerics

- 6. Current implementations
- 7. Current problems

- 7.1 Nicknames
- 7.2 Limitation of wildcards
- 7.3 Security considerations

- 8. Current support and availability
- 9. Acknowledgements
- 10. References
- 11. Author's Address
- 12. Full Copyright Statement

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_LINKSRPL_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.

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