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.nr LT 7.2i
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.ds RF FORMFEED[Page %]
.ds CF
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.ds RH 15 January 2007
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.nf
Network Working Group                                        P. Riikonen
Internet-Draft
draft-riikonen-silc-commands-07.txt                      15 January 2007
Expires: 15 July 2007

.in 3

.ce 2
SILC Commands
<draft-riikonen-silc-commands-07.txt>

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Status of this Draft

By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79.

Internet-Drafts are working documents of the Internet Engineering
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The list of current Internet-Drafts can be accessed at
http://www.ietf.org/1id-abstracts.html
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.


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Abstract

This memo describes the commands used in the Secure Internet Live
Conferencing (SILC) protocol, specified in the Secure Internet Live
Conferencing, Protocol Specification [SILC1].  The SILC Commands are
very important part of the SILC protocol.  Usually the commands are used
by SILC clients to manage the SILC session, but also SILC servers may
use the commands.  This memo specifies detailed command messages and
command reply messages.








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Table of Contents

.nf
1 Introduction ..................................................  2
  1.1 Requirements Terminology ..................................  2
2 SILC Commands .................................................  2
  2.1 SILC Commands Syntax ......................................  4
  2.2 SILC Command Argument Idioms ..............................  4
  2.3 SILC Commands List ........................................  5
  2.4 SILC Command Status Payload ............................... 43
3 SILC Status Types ............................................. 44
4 Security Considerations ....................................... 51
5 References .................................................... 51
6 Author's Address .............................................. 52
Appendix A ...................................................... 52
Full Copyright Statement ........................................ 54


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1. Introduction

This document describes the commands used in the Secure Internet Live
Conferencing (SILC) protocol, specified in the Secure Internet Live
Conferencing, Protocol Specification [SILC1].  This document specifies
detailed command messages and command reply messages.

Commands are very important part on SILC network especially for client
which uses commands to operate on the SILC network.  Commands are used
to set nickname, join to channel, change modes and many other things.

See the [SILC1] for the requirements and the restrictions for the usage
of the SILC commands.  The [SILC2] defines the command packet type and
the Command Payload which is actually used to deliver the commands and
command reply messages.


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1.1 Requirements Terminology

The keywords MUST, MUST NOT, REQUIRED, SHOULD, SHOULD NOT, RECOMMENDED,
MAY, and OPTIONAL, when they appear in this document, are to be
interpreted as described in [RFC2119].


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2 SILC Commands

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2.1 SILC Commands Syntax

This section briefly describes the syntax of the command notions
in this document.  Every field in command is separated from each
other by whitespaces (` ') indicating that each field is independent
argument and each argument MUST have own Command Argument Payload.
The number of maximum arguments are defined with each command
separately.  The Command Argument Payload is described in [SILC2].

Every command defines specific number for each argument.  Currently,
they are defined in ascending order; first argument has number one
(1), second has number two (2) and so on.  This number is set into the
Argument Type field in the Command Argument Payload.  This makes it
possible to send the arguments in free order as the number MUST be
used to identify the type of the argument.  This makes is it also
possible to have multiple optional arguments in commands and in
command replies.  The number of argument is marked in parentheses
before the actual argument.



.in 6
Example:  Arguments:  (1) <nickname> (2) <username@host>
.in 3


Every command replies with Status Payload.  This payload tells the
sender of the command whether the command was completed successfully or
whether there was an error.  If error occurred the payload includes the
error type.  In the next section the Status Payload is not described
as it is common to all commands and has been described here.  Commands
MAY reply with other arguments as well.  These arguments are command
specific and are described in the next section.

Example command:
.in 6

EXAMPLE_COMMAND

.in 8
Max Arguments:  3
    Arguments:  (1) <nickname>[@<server>]  (2) <message>
                (3) [<count>]

The command has maximum of 3 arguments.  However, only first
and second arguments are mandatory.

First argument <nickname> is mandatory but may have optional
<nickname@server> format as well.  Second argument is mandatory
<message> argument.  Third argument is optional <count> argument.

The numbers in parentheses are the argument specific numbers
that specify the type of the argument in Command Argument Payload.
The receiver always knows that, say, argument number two (2) is
<message> argument, regardless of the ordering of the arguments in
the Command Payload.

Reply messages to the command:

Max Arguments:  4
    Arguments:  (1) <Status Payload>  (2) [<channel list>]
                (3) <idle time>       (4) [<away message>]

This command may reply with maximum of 4 arguments.  However,
only the first and third arguments are mandatory.  The numbers
in the parentheses have the same meaning as in the upper
command sending specification.

Every command reply with <Status Payload>, it is mandatory
argument for all command replies and for this reason it is not
described in the command reply descriptions.



Status messages:

    SILC_STATUS_OK
    SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
    SILC_STATUS_ERR_NO_SUCH_NICK

Every command reply also defines set of status message that it
may return inside the <Status Payload>.  All status messages
are defined in the section 2.3 SILC Command Status Payload
The status messages defined with the command are recommendations.
It is possible to return other status messages not listed with
the command reply definition.
.in 3


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2.2 SILC Command Argument Idioms

All commands that has an ID as argument (for example <Client ID>) are
actually ID Payloads, defined in [SILC2] that includes the type of the
ID, length of the ID and the actual ID data.  This way variable length
ID's can be sent as arguments.

All passphrases that may be sent in commands as arguments MUST be
UTF-8 [RFC3629] encoded.  All strings sent as arguments in command and
command reply are also UTF-8 encoded, unless otherwise defined.  See
the [SILC1] for general UTF-8 definition in SILC protocol.

All public keys and certificates that are sent as arguments are actually
Public Key Payloads [SILC2].  This way it is possible to send different
kind of public keys and certificate types as arguments.




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2.3 SILC Commands List

This section lists all SILC commands, however, it is expected that a
implementation and especially client implementation has many more
commands that has only local affect.  These commands are official
SILC commands that has both client and server sides and cannot be
characterized as local commands.

List of all defined commands in SILC follows.

.in 0
   0    SILC_COMMAND_NONE

        None.  This is reserved command and MUST NOT be sent.


   1    SILC_COMMAND_WHOIS

        Max Arguments:  256
            Arguments:  (1) [<nickname>[@<server>]]   (2) [<count>]
                        (3) [<Requested Attributes>]  (4) [<Client ID>]
                        (n) [...]

        Whois command is used to query various information about specific
        user.  The user may be requested by their nickname and server name.
        The query may find multiple matching users as there are no unique
        nicknames in the SILC.  The <count> option may be given to narrow
        down the number of accepted results.  If this is not defined there
        are no limit of accepted results.  The query may also be narrowed
        down by defining the server name of the nickname.  The <count> is
        32 bit MSB first order integer.

        It is also possible to search the user by Client ID.  If the
        <Client ID> is provided server MUST use it as the search value
        instead of the <nickname>.  It is also possible to define multiple
        Client ID's to search multiple users sending only one WHOIS
        command.  In this case the Client ID's are appended as normal
        arguments.

        The <Requested Attributes> is defined in [ATTRS] and can be used
        to request various information about the client.  See Appendix A
        for definition of using these attributes in SILC.  If neither the
        <nickname> or <Client ID> arguments are present but the attributes
        are, the server MUST use the attributes to do the searching.  If
        none of the arguments, <nickname>, <Client ID> and <Requested
        Attributes> are present, error MUST be retuned.  Server MAY
        use the <Requested Attributes> to narrow down the search if they
        present at any time.

        To prevent miss-use of this command wildcards in the nickname
        or in the server name are not permitted.  It is not allowed
        to request all users on some server.  The WHOIS requests MUST
        be based on explicit nickname request.

        The WHOIS request MUST be always sent to the router by normal
        server so that all users are searched.  However, the server still
        MUST search its locally connected clients.  The router MUST send
        this command to the server which owns the requested client, if
        the router is unable to provide all mandatory information about
        the client.  That server MUST reply to the command.  Server MUST
        NOT send whois replies to the client until it has received the
        reply from its router.

        Reply messages to the command:

        Max Arguments:  11
            Arguments:  (1) <Status Payload>       (2) <Client ID>
                        (3) <nickname>[@<server>]  (4) <username@host>
                        (5) <real name>            (6) [<Channel Payload
                                                         list>]
                        (7) [<user mode>]          (8) [<idle time>]
                        (9) [<fingerprint>]        (10) <channel user
                                                         mode list>
                        (11) [<Attributes>]


        This command may reply with several command reply messages to
        form a list of results.  In this case the status payload will
        include STATUS_LIST_START status in the first reply and
        STATUS_LIST_END in the last reply to indicate the end of the
        list.  If there are only one reply the status is set to normal
        STATUS_OK.  If multiple Client IDs was requested then each found
        and unfound client MUST cause successful or error reply,
        respectively.

        The command replies include the Client ID of the nickname,
        nickname and server name, user name and host name and user's real
        name.  Client should process these replies only after the last
        reply has been received with the STATUS_LIST_END status.  If the
        <count> option were defined in the query there will be only
        <count> many replies from the server.

        The server returns the list of channels if the client has
        joined channels.  In this case the list is list of Channel
        Payloads.  The Mode Mask in the Channel Payload is the channel's
        mode.  The list is encoded by adding the Channel Payloads one
        after the other.  Private and secret channels MUST NOT be sent,
        except if the sender of this command is on those channels, or
        the sender is server.  The <channel user mode list> MUST also
        be sent if client is joined channels.  This list includes 32 bit
        MSB first order values one after the other and each indicate
        the user's mode on a channel.  The order of these values MUST
        be same as the channel order in the <Channel Payload list>.

        The server also returns client's user mode, idle time, and the
        fingerprint of the client's public key.  The <fingerprint> is the
        binary hash digest of the public key.  The fingerprint MUST NOT
        be sent if the server has not verified the proof of possession of
        the corresponding private key.  Server can do this during the
        SILC Key Exchange protocol.  The <fingerprint> is SHA1 digest.

        The <Attributes> is the reply to the <Requested Attributes>.
        See the Appendix A for more information.

        Status messages:

            SILC_STATUS_OK
            SILC_STATUS_LIST_START
            SILC_STATUS_LIST_END
            SILC_STATUS_ERR_NO_SUCH_NICK
            SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
            SILC_STATUS_ERR_WILDCARDS
            SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
            SILC_STATUS_ERR_TOO_MANY_PARAMS


   2    SILC_COMMAND_WHOWAS

        Max Arguments:  2
            Arguments:  (1) <nickname>[@<server>]  (2) [<count>]

        Whowas.  This command is used to query history information about
        specific user.  The user may be requested by their nickname and
        server name.  The query may find multiple matching users as there
        are no unique nicknames in the SILC.  The <count> option may be
        given to narrow down the number of accepted results.  If this
        is not defined there are no limit of accepted results.  The query
        may also be narrowed down by defining the server name of the
        nickname.  The <count> is 32 bit MSB first order integer.

        To prevent miss-use of this command wildcards in the nickname
        or in the server name are not permitted.  The WHOWAS requests MUST
        be based on specific nickname request.

        The WHOWAS request MUST be always sent to the router by server
        so that all users are searched.  However, the server still must
        search its locally connected clients.

        Reply messages to the command:

        Max Arguments:  5
            Arguments:  (1) <Status Payload>        (2) <Client ID>
                        (3) <nickname>[@<server>]   (4) <username@host>
                        (5) [<real name>]

        This command may reply with several command reply messages to form
        a list of results.  In this case the status payload will include
        STATUS_LIST_START status in the first reply and STATUS_LIST_END in
        the last reply to indicate the end of the list.  If there are only
        one reply the status is set to normal STATUS_OK.

        The command replies with nickname and user name and host name.
        Every server MUST keep history for some period of time of its
        locally connected clients.

        Status messages:

            SILC_STATUS_OK
            SILC_STATUS_LIST_START
            SILC_STATUS_LIST_END
            SILC_STATUS_ERR_NO_SUCH_NICK
            SILC_STATUS_ERR_WILDCARDS
            SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
            SILC_STATUS_ERR_TOO_MANY_PARAMS


   3    SILC_COMMAND_IDENTIFY

        Max Arguments:  256
            Arguments:  (1) [<nickname>[@<server>]]  (2) [<server name>]
                        (3) [<channel name>]         (4) [<count>]
                        (5) [<ID Payload>]           (n) [...]

        Identify command is used to query information about an entity by
        the entity's name or ID.  This command can be used to query
        information about clients, servers and channels.

        The query may find multiple matching entities.  The <count> option
        may be given to narrow down the number of accepted results.  If
        this is not defined there are no limit of accepted results.  The
        <count> is 32 bit MSB first order integer.

        It is also possible to search the entity by its ID.  If the
        <ID Payload> is provided server must use it as the search value
        instead of the entity's name.  One of the arguments MUST be given.
        It is also possible to define multiple ID Payloads to search
        multiple entities sending only one IDENTIFY command.  In this case
        the ID Payloads are appended as normal arguments.  The type of the
        entity is defined by the type of the ID Payload.

        To prevent miss-use of this command wildcards in the names are
        not permitted.  It is not allowed to request for example all users
        on server.

        Implementations may not want to give interface access to this
        command as it is hardly a command that would be used by an end
        user.  However, it must be implemented as it is most likely used
        with private message sending.

        The IDENTIFY command MUST be always sent to the router by server
        so that all users are searched.  However, server MUST still search
        its locally connected clients.

        Reply messages to the command:

        Max Arguments:  4
            Arguments:  (1) <Status Payload>   (2) <ID Payload>
                        (3) [<entity's name>]  (4) [<info>]

        This command may reply with several command reply messages to form
        a list of results.  In this case the status payload will include
        STATUS_LIST_START status in the first reply and STATUS_LIST_END in
        the last reply to indicate the end of the list.  If there are only
        one reply the status is set to normal STATUS_OK.  If multiple Client
        IDs was requested then each found and unfound client must cause
        successful or error reply, respectively.

        When querying clients the <entity's name> must include the client's
        nickname in the following format: nickname[@server].  The
        <info> must include the client's username and host in the following
        format: username@host.

        When querying servers the <entity's name> must include the server's
        full name.  The <info> may be omitted.

        When querying channels the <entity's name> must include the
        channel's name.  The <info> may be omitted.

        If the <count> option were defined in the query there will be only
        <count> many replies from the server.

        Status messages:

            SILC_STATUS_OK
            SILC_STATUS_LIST_START
            SILC_STATUS_LIST_END
            SILC_STATUS_ERR_NO_SUCH_NICK
            SILC_STATUS_ERR_NO_SUCH_SERVER
            SILC_STATUS_ERR_NO_SUCH_CHANNEL
            SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
            SILC_STATUS_ERR_NO_SUCH_SERVER_ID
            SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
            SILC_STATUS_ERR_WILDCARDS
            SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
            SILC_STATUS_ERR_TOO_MANY_PARAMS


   4    SILC_COMMAND_NICK

        Max Arguments:  1
            Arguments:  (1) <nickname>

        Set/change nickname.  This command is used to set nickname for
        user.  See [SILC1] for definition of correctly formatted
        nickname.

        When nickname is changed new Client ID is generated.  Server MUST
        distribute SILC_NOTIFY_TYPE_NICK_CHANGE to local clients on the
        channels (if any) the client is joined on.  Then it MUST send
        SILC_NOTIFY_TYPE_NICK_CHANGE notify to its primary route to
        notify about nickname and Client ID change.

        Reply messages to the command:

        Max Arguments:  3
            Arguments:  (1) <Status Payload>  (2) <New ID Payload>
                        (3) <nickname>

        This command replies always with <New ID Payload> that is
        generated by the server every time user changes their nickname.
        Client receiving this payload MUST start using the received
        Client ID as its current valid Client ID.  The New ID Payload
        is described in [SILC2].  The <nickname> is the user's new
        nickname.

        Status messages:

            SILC_STATUS_OK
            SILC_STATUS_ERR_WILDCARDS
            SILC_STATUS_ERR_NICKNAME_IN_USE
            SILC_STATUS_ERR_BAD_NICKNAME
            SILC_STATUS_ERR_NOT_REGISTERED
            SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
            SILC_STATUS_ERR_TOO_MANY_PARAMS


   5    SILC_COMMAND_LIST

        Max Arguments:  1
            Arguments:  (1) [<Channel ID>]

        The list command is used to list channels and their topics on the
        current server.  If the <Channel ID> parameter is used, only the
        status of that channel is displayed.  Secret channels are not
        listed at all.  Private channels are listed with status indicating
        that the channel is private.  Router MAY reply with all channels
        it knows about.

        Reply messages to the command:

        Max Arguments:  5
            Arguments:  (1) <Status Payload>  (2) <Channel ID>
                        (3) <channel>         (4) [<topic>]
                        (5) [<user count>]

        This command may reply with several command reply messages to form
        a list of results.  In this case the status payload will include
        STATUS_LIST_START status in the first reply and STATUS_LIST_END in
        the last reply to indicate the end of the list.  If there are only
        one reply the status is set to normal STATUS_OK.

        This command replies with Channel ID, name and the topic of the
        channel.  If the channel is private channel the <topic> SHOULD
        include the "*private*" string.

        Status messages:

            SILC_STATUS_OK
            SILC_STATUS_LIST_START
            SILC_STATUS_LIST_END
            SILC_STATUS_ERR_WILDCARDS
            SILC_STATUS_ERR_NOT_REGISTERED
            SILC_STATUS_ERR_TOO_MANY_PARAMS
            SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
            SILC_STATUS_ERR_NO_CHANNEL_ID
            SILC_STATUS_ERR_NO_SUCH_SERVER


   6    SILC_COMMAND_TOPIC

        Max Arguments:  2
            Arguments:  (1) <Channel ID>  (2) [<topic>]

        This command is used to change or view the topic of a channel.
        The topic for channel <Channel ID> is returned if there is no
        <topic> given.  If the <topic> parameter is present, the topic
        for that channel will be changed, if the channel modes permit
        this action.

        After setting the topic the server MUST send the notify type
        SILC_NOTIFY_TYPE_TOPIC_SET to its primary router and then to
        the channel which topic was changed.

        Reply messages to the command:

        Max Arguments:  2
            Arguments:  (1) <Status Payload>  (2) <Channel ID>
                        (3) [<topic>]

        The command may reply with the topic of the channel if it is
        set.

        Status messages:

            SILC_STATUS_OK
            SILC_STATUS_ERR_NOT_ON_CHANNEL
            SILC_STATUS_ERR_WILDCARDS
            SILC_STATUS_ERR_NOT_REGISTERED
            SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
            SILC_STATUS_ERR_NO_SUCH_CHANNEL
            SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
            SILC_STATUS_ERR_NO_CHANNEL_ID
            SILC_STATUS_ERR_BAD_CHANNEL_ID
            SILC_STATUS_ERR_TOO_MANY_PARAMS
            SILC_STATUS_ERR_NO_CHANNEL_PRIV


   7    SILC_COMMAND_INVITE

        Max Arguments:  4
            Arguments:  (1) <Channel ID>       (2) [<Client ID>]
                        (3) [<add | del>]      (4) [<invite list>]

        This command can be used to invite other clients to join to a
        channel, and to manage the channel's invite list.  The <Client
        ID> argument is the target client's ID that is being invited.
        The <Channel ID> is the Channel ID of the requested channel.
        The sender of this command MUST be on the channel.  The server
        MUST also send the notify type SILC_NOTIFY_TYPE_INVITE to its
        primary router and then to the client indicated by the <Client
        ID>.

        The <add | del> is an argument of size of 1 byte where 0x00 means
        adding a client to invite list, and 0x01 means deleting a client
        from invite list.  The <invite list>, if present, indicates
        the information to be added to or removed from the invite list.
        It may include a string for matching clients, public key of a
        client (Public Key Payload) or Client ID of a client.  The
        <invite list> is an Argument List Payload.

        The following Argument Types has been defined for invite list
        Argument Payloads:

          0x01 - Argument is an invite string of following format:

            [<nickname>[@<server>]!][<username>]@[<hostname or IP/MASK>]

            The <hostname> may also be in format of IP/MASK to indicate
            a network, for example 10.2.1.0/255.255.0.0.

          0x02 - Argument is the public key of a client
          0x03 - Argument is the Client ID of a client

        If unknown type value is received or there is invalid amount of
        Argument Payloads present in the list, the command MUST be
        discarded.  When argument that is to be deleted from the invite
        list does not exist in the list the argument is ignored.

        When adding to or removing from the invite list the server MUST
        send the notify type SILC_NOTIFY_TYPE_INVITE to its primary router.
        When the SILC_CHANNEL_MODE_INVITE is set the client which executes
        this command MUST have at least channel operator privileges to be
        able to add to or remove from the invite list.  If this channel
        mode is not set the list manipulation is allowed for all clients.
        Wildcards MAY be used with this command.  When this command is
        used to invite explicit client with <Client ID> the ID MUST be
        added to the invite list by the server.

        When this command is given with only <Channel ID> argument then
        the command merely returns the invite list of the channel.   This
        command MUST fail if the requested channel does not exist, the
        requested <Client ID> is already on the channel or if the channel
        is invite only channel and the caller of this command does not
        have at least channel operator privileges on the channel.

        Reply messages to the command:

        Max Arguments:  3
            Arguments:  (1) <Status Payload>  (2) <Channel ID>
                        (3) [<invite list>]

	This command replies with the invite list of the channel if it
	exists.

        Status messages:

            SILC_STATUS_OK
            SILC_STATUS_ERR_NOT_REGISTERED
            SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
            SILC_STATUS_ERR_TOO_MANY_PARAMS
            SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
            SILC_STATUS_ERR_NO_CLIENT_ID
            SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
            SILC_STATUS_ERR_NO_CHANNEL_ID
            SILC_STATUS_ERR_NOT_ON_CHANNEL
            SILC_STATUS_ERR_USER_ON_CHANNEL
            SILC_STATUS_ERR_NO_CHANNEL_PRIV
            SILC_STATUS_ERR_RESOURCE_LIMIT


   8    SILC_COMMAND_QUIT

        Max Arguments:  1
            Arguments:  (1) [<quit message>]

        This command is used by client to end SILC session.  The server
        must close the connection to a client which sends this command.
        if <quit message> is given it will be sent to other clients on
        channel if the client is on channel when quitting.

        Reply messages to the command:

        This command does not reply anything.


    9   SILC_COMMAND_KILL

        Max Arguments:  3
            Arguments:  (1) <Client ID>          (2) [<comment>]
                        (3) [<auth payload>]

        This command can be used by SILC operators to remove a client from
        SILC network.  It also can be used by a normal client to remove
        its own client from network by providing correct authentication
        data.

        Router operator killing a client:

        The removing has temporary effects and client may reconnect to
        SILC network.  The <Client ID> is the client to be removed from SILC.
        The <comment> argument may be provided to give to the removed client
        some information why it was removed from the network.  The killer
        MUST have SILC operator privileges.

        When killing a client the router MUST first send notify type
        SILC_NOTIFY_TYPE_KILLED to all channels the client has joined.
        The packet MUST NOT be sent to the killed client on the channels.
        Then, the router MUST send the same notify type to its primary
        router.  Finally, the router MUST send the same notify type
        destined directly to the client which was killed.  The killed
        client MUST also be removed from the invite lists of joined
        channels if it is explicitly added in the invite lists.

        Normal client killing by authentication:

        When normal client executes this command the <Client ID> is the
        destination client to be removed from the network.  The client
        MUST provide the <auth payload> which includes a digital signature
        that MUST be verified with the public key of the client indicated
        by <Client ID>.  The <Client ID> MUST be local client to the server.
        If the signature verification is successful the server sends
        SILC_NOTIFY_TYPE_SIGNOFF to network and to the destination client.
        The SILC_NOTIFY_TYPE_KILLED MUST NOT be used in this case.  If the
        verification fails the destination client remains in network.
        The hash function used in <auth payload> computing is selected
        by user or SHA1 otherwise.

        Reply messages to the command:

        Max Arguments:  2
            Arguments:  (1) <Status Payload>  (2) <Client ID>

        This command returns with the requested Client ID.

        Status messages:

            SILC_STATUS_OK
            SILC_STATUS_ERR_WILDCARDS
            SILC_STATUS_ERR_NOT_REGISTERED
            SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
            SILC_STATUS_ERR_TOO_MANY_PARAMS
            SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
            SILC_STATUS_ERR_NO_CLIENT_ID
            SILC_STATUS_ERR_NO_ROUTER_PRIV


   10   SILC_COMMAND_INFO

        Max Arguments:  2
            Arguments:  (1) [<server>]  (2) [<Server ID>]

        This command is used to fetch various information about a server.
        If <server> argument is specified the command MUST be sent to
        the requested server.

        If the <Server ID> is specified the server information if fetched
        by the provided Server ID.  One of the arguments MUST always be
        present.

        Reply messages to the command:

        Max Arguments:  4
            Arguments:  (1) <Status Payload>  (2) <Server ID>
                        (3) <server name>     (4) <string>

        This command replies with the Server ID of the server and a
        string which tells the information about the server.

        Status messages:

            SILC_STATUS_OK
            SILC_STATUS_ERR_WILDCARDS
            SILC_STATUS_ERR_NOT_REGISTERED
            SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
            SILC_STATUS_ERR_TOO_MANY_PARAMS
            SILC_STATUS_ERR_NO_SUCH_SERVER
            SILC_STATUS_ERR_NO_SUCH_SERVER_ID
            SILC_STATUS_ERR_NO_SERVER_ID


   11   SILC_COMMAND_STATS

        Max Arguments:  1
            Arguments:  (1) <Server ID>

        This command is used to fetch various statistical information
        from the server indicated by <Server ID>, which is the ID of
        server where sender is connected to.  Server receiving this
        command MAY also send this further to its router for fetching
        other cell and network wide statistics to accompany the reply.

        Reply messages to the command:

        Max Arguments:  3
            Arguments:  (1) <Status Payload>          (2) <Server ID>
                        (3) [<statistics structure>]

        This command replies with the Server ID of the server and
        optional statistics structure which includes 32 bit MSB first
        ordered integer values to represent various statistical
        information.  The structure is as follows:

          starttime      - time when server was started
          uptime         - uptime of the server
          my clients     - number of locally connected clients
          my channels    - number of locally created channels
          my server ops  - number of local server operators
          my router ops  - number of local router operators
          cell clients   - number of clients in local cell
          cell channels  - number of channels in local cell
          cell servers   - number of servers in local cell
          clients        - number of client in SILC network
          channels       - number of channels in SILC network
          servers        - number of servers in SILC network
          routers        - number of routers in SILC network
          server ops     - number of server operators in SILC network
          router ops     - number of router operators in SILC network

        If some value is unknown it is set to zero (0) value.  The
        "starttime" is the start time of the server, and is seconds
        since Epoch (POSIX.1).  The "uptime" is time difference of
        current time and "starttime" in the server, and is seconds
        in value.

        Status messages:

            SILC_STATUS_OK
            SILC_STATUS_ERR_NOT_REGISTERED
            SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
            SILC_STATUS_ERR_TOO_MANY_PARAMS
            SILC_STATUS_ERR_NO_SUCH_SERVER_ID
            SILC_STATUS_ERR_NO_SUCH_SERVER
            SILC_STATUS_ERR_NO_SERVER_ID


   12   SILC_COMMAND_PING

        Max Arguments:  1
            Arguments:  (1) <Server ID>

        This command is used by client and server to test the communication
        channel to its server if one suspects that the communication is not
        working correctly.  The <Server ID> is the ID of the server the
        sender is connected to.

        Reply messages to the command:

        Max Arguments:  1
            Arguments:  (1) <Status Payload>

        This command replies only with Status Payload.  Server returns
        SILC_STATUS_OK in Status Payload if pinging was successful.



        Status messages:

            SILC_STATUS_OK
            SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
            SILC_STATUS_ERR_TOO_MANY_PARAMS
            SILC_STATUS_ERR_NO_SERVER_ID
            SILC_STATUS_ERR_NO_SUCH_SERVER
            SILC_STATUS_ERR_NOT_REGISTERED


   13   SILC_COMMAND_OPER

        Max Arguments:  2
            Arguments:  (1) <username>  (2) <authentication payload>

        This command is used by normal client to obtain server operator
        privileges on some server or router.  Note that router operator
        has router privileges that supersedes the server operator
        privileges and this does not obtain those privileges.  Client
        MUST use SILCOPER command to obtain router level privileges.

        The <username> is the username set in the server configurations
        as operator.  The <authentication payload> is the data that the
        client is authenticated against.  It may be passphrase prompted
        for user on client's screen or it may be public key authentication
        based on digital signatures.  The public key used to verify the
        signature should be locally saved in the server, and server should
        not use public key received during the SKE to verify this signature.

        After changing the mode the server MUST send the notify type
        SILC_NOTIFY_TYPE_UMODE_CHANGE to its primary router.

        Reply messages to the command:

        Max Arguments:  1
            Arguments:  (1) <Status Payload>

        This command replies only with Status Payload.

        Status messages:

            SILC_STATUS_OK
            SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
            SILC_STATUS_ERR_TOO_MANY_PARAMS
            SILC_STATUS_ERR_NOT_REGISTERED
            SILC_STATUS_ERR_AUTH_FAILED


   14   SILC_COMMAND_JOIN

        Max Arguments:  7
            Arguments:  (1) <channel>         (2) <Client ID>
                        (3) [<passphrase>]    (4) [<cipher>]
                        (5) [<hmac>]          (6) [<founder auth>]
                        (7) [<channel auth>]

        Join to channel/create new channel.  This command is used to
        join to a channel.  If the channel does not exist the channel is
        created.  If server is normal server this command MUST be sent
        to router which will create the channel.  The channel MAY be
        protected with passphrase.  If this is the case the passphrase
        MUST be sent along the join command.  See the [SILC1] for
        definition of correctly formatted channel name, <channel>.

        The second argument <Client ID> is the Client ID of the client
        which is joining to the client.  When client sends this command
        to the server the <Client ID> MUST be the client's own ID.

        Cipher to be used to secure the traffic on the channel MAY be
        requested by sending the name of the requested <cipher>.  This
        is used only if the channel does not exist and is created.  If
        the channel already exists the cipher set previously for the
        channel will be used to secure the traffic.  The computed MACs
        of the channel message are produced by the default HMAC or by
        the <hmac> provided for the command.

        The <founder auth> is Authentication Payload providing the
        authentication for gaining founder privileges on the channel
        when joining the channel.  The client may provide this if it
        knows that it is the founder of the channel and that the
        SILC_CMODE_FOUNDER_AUTH mode is set on the channel.  The server
        MUST verify whether the client is able to gain the founder
        privileges the same way as the client had given the
        SILC_COMMAND_CUMODE command to gain founder privileges.  The
        client is still able to join the channel even if the founder
        privileges could not be gained.  The hash function used with
        the <founder payload> is selected by user or SHA1 otherwise.

        If the <channel auth> is present and the channel mode
        SILC_CMODE_CHANNEL_AUTH is set the server MUST verify the
        <channel auth> with channel public key(s).  If public key that
        can verify <channel auth> does not exist on the channel public
        key list the client MUST NOT be allowed to join the channel.
        Because more than one public key may be set on channel the
        <channel auth> Authentication Payload's Public Data field
        MUST include an indication of the public key to be used.  The
        first 20 bytes of the Public Data field MUST be SHA-1 digest of
        the public key that must be used in verification.  The digest
        is the SILC Public Key fingerprint.  Rest of thePublic Data field
        are set as defined in [SILC1].  This way server can determine from
        the digest whether that public key exist on the channel and then
        use that key in verification.  The hash function used with
        <channel auth> is selected by user or SHA1 otherwise.

        The server MUST check whether the user is allowed to join to
        the requested channel.  Various modes set to the channel affect
        the ability of the user to join the channel.  These conditions
        are:

            o  The user MUST be invited to the channel if the channel
               is invite-only channel.

            o  The Client ID/nickname/username/host name/public key
               MUST NOT match any active bans.

            o  The correct passphrase MUST be provided if passphrase
               is set to the channel, and/or digital signature verification
               with channel public key MUST be successful if public keys
               has been set to the channel.

            o  The user count limit, if set, MUST NOT be reached.

        If the client provided correct <founder auth> payload it can
        override these conditions, except the condition for the passphrase.
        The correct passphrase MUST be provided even if <founder auth>
        payload is provided.

        Reply messages to the command:

        Max Arguments:  17
            Arguments:  (1) <Status Payload>        (2) <channel>
                        (3) <Channel ID>            (4) <Client ID>
                        (5) <channel mode mask>     (6) <created>
                        (7) [<Channel Key Payload>] (8) [<ban list>]
                        (9) [<invite list>]         (10) [<topic>]
                        (11) [<hmac>]               (12) <list count>
                        (13) <Client ID list>       (14) <client mode list>
                        (15) [<founder pubkey>]     (16) [<channel pubkeys>]
                        (17) [<user limit>]

        This command replies with the channel name requested by the
        client, channel ID of the channel and topic of the channel
        if it exists.  The <Client ID> is the Client ID which was joined
        to the channel.  It also replies with the channel mode mask
        which tells all the modes set on the channel.  If the channel
        is created the mode mask is zero (0) and <created> is 0x01.
        If ban mask and/or invite list is set they are sent as well.
        The <user limit> is the user limit on the channel, if one is set.

        The <list count>, <Client ID list> and <client mode list> are
        the clients currently on the channel and their modes on the
        channel.  The <Client ID list> is formed by adding the ID Payloads
        one after the other.  The <client mode list> is formed by adding
        32 bit MSB first order values one after the other.  The <founder
        pubkey> is the public key (or certificate) of the channel founder.
        The <channel pubkeys> is Argument List Payload containing the
        channel public keys that has been set for the channel.

        Client receives the channel key in the reply message as well
        inside <Channel Key Payload>.

        Status messages:

            SILC_STATUS_OK
            SILC_STATUS_ERR_WILDCARDS
            SILC_STATUS_ERR_NOT_REGISTERED
            SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
            SILC_STATUS_ERR_TOO_MANY_PARAMS
            SILC_STATUS_ERR_BAD_PASSWORD
            SILC_STATUS_ERR_CHANNEL_IS_FULL
            SILC_STATUS_ERR_NOT_INVITED
            SILC_STATUS_ERR_BANNED_FROM_CHANNEL
            SILC_STATUS_ERR_BAD_CHANNEL
            SILC_STATUS_ERR_USER_ON_CHANNEL


   15   SILC_COMMAND_MOTD

        Max Arguments:  1
            Arguments:  (1) <server>

        This command is used to query the Message of the Day of the server.

        Reply messages to the command:

        Max Arguments:  3
            Arguments:  (1) <Status Payload>  (2) <Server ID>
                        (3) [<motd>]

        This command replies with the motd message if it exists.

        Status messages:

            SILC_STATUS_OK
            SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
            SILC_STATUS_ERR_TOO_MANY_PARAMS
            SILC_STATUS_ERR_NOT_REGISTERED
            SILC_STATUS_ERR_NO_SUCH_SERVER


   16   SILC_COMMAND_UMODE

        Max Arguments:  2
            Arguments:  (1) <Client ID>  (2) [<client mode mask>]

        This command is used by client to set/unset modes for itself.
        However, there are some modes that the client MUST NOT set itself,
        but they will be set by server.  However, client MAY unset any
        mode.  Modes may be masked together ORing them thus having
        several modes set.  Client MUST keep its client mode mask
        locally so that the mode setting/unsetting would work without
        problems.  Client may change only its own modes.

        After changing the mode server MUST send the notify type
        SILC_NOTIFY_TYPE_UMODE_CHANGE to its primary router.

        The following client modes are defined:

           0x00000000    SILC_UMODE_NONE

              No specific mode for client.  This is the initial
              setting when new client is created.  The client is
              normal client and is present in the network.


           0x00000001    SILC_UMODE_SERVER_OPERATOR

              Marks the user as server operator.  Client MUST NOT
              set this mode itself.  Server sets this mode to the
              client when client attains the server operator
              privileges by SILC_COMMAND_OPER command.  Client
              MAY unset the mode itself.


           0x00000002    SILC_UMODE_ROUTER_OPERATOR

              Marks the user as router (SILC) operator.  Client
              MUST NOT set this mode itself.  Router sets this mode
              to the client when client attains the router operator
              privileges by SILC_COMMAND_SILCOPER command.  Client
              MAY unset the mode itself.


           0x00000004    SILC_UMODE_GONE

              Marks that the user is not currently present in the
              SILC Network.  Client MAY set and unset this mode.


           0x00000008    SILC_UMODE_INDISPOSED

              Marks that the user is currently indisposed and may
              not be able to receive any messages, and that user may
              not be present in the network.  Client MAY set and
              unset this mode.


           0x00000010    SILC_UMODE_BUSY

              Marks that the user is currently busy and may not
              want to receive any messages, and that user may not
              be present in the network.  Client MAY set and unset
              this mode.


           0x00000020    SILC_UMODE_PAGE

              User is not currently present or is unable to receive
              messages, and prefers to be paged in some mechanism
              if the user needs to be reached.  Client MAY set and
              unset this mode.


           0x00000040    SILC_UMODE_HYPER

              Marks that the user is hyper active and is eager to
              receive and send messages.   Client MAY set and unset
              this mode.


           0x00000080    SILC_UMODE_ROBOT

              Marks that the client is actually a robot program.
              Client MAY set and unset this mode.


           0x00000100    SILC_UMODE_ANONYMOUS

              Marks that the client is anonymous client.  Server
              that specifically is designed for anonymous services
              can set and unset this mode.  Client MUST NOT set or
              unset this mode itself.  A client with this mode set
              would have the username and the hostname information
              scrambled by the server which set this mode.


           0x00000200    SILC_UMODE_BLOCK_PRIVMSG

              Marks that the client wishes to block private
              messages sent to the client, unless the Private
              Message Key flag is set in the SILC packet header.
              If this mode is set server MUST NOT deliver private
              messages to the client without the Private Message
              Key flag being set.  The Private Message Key flag set
              indicates that the private message is protected with
              a key shared between the sender and the recipient.

              A separate service could provide additional filtering
              features for accepting private messages from certain
              sender.  However, this document does not specify such
              service.

              The client MAY set and unset this mode.


           0x00000400    SILC_UMODE_DETACHED

              Marks that the client is detached from the SILC network.
              This means that the actual network connection to the
              client is lost but the client entry is still valid.  The
              detached client can be resumed at a later time.  This
              mode MUST NOT be set by client.  It can only be set when
              client has issued command SILC_COMMAND_DETACH.  The server
              sets this mode.  This mode cannot be unset with this
              command.  It is unset when the client is resuming back to
              the network and SILC_PACKET_RESUME_CLIENT packet is
              received.

              This flag MUST NOT be used to determine whether a packet
              can be sent to the client or not.  Only the server that
              had the original client connection can make the decision
              by knowing that the network connection is not active.
              In this case the default case is to discard the packet.


           0x00000800    SILC_UMODE_REJECT_WATCHING

              Marks that the client rejects that it could be watched
              by someone else.  If this mode is set notifications about
              this client is not send, even if someone is watching the
              same nickname this client has.  Client MAY set and unset
              this mode.  Any changes for this client MUST NOT be
              notified to any watcher when this mode is set.

              A separate service could provide additional filtering
              features for rejecting and accepting the watching from
              certain users.  However, this document does not specify
              such service.


           0x00001000    SILC_UMODE_BLOCK_INVITE

              Marks that the client wishes to block incoming invite
              notifications.  Client MAY set and unset this mode.
              When set server does not deliver invite notifications
              to the client.  Note that this mode may make it harder
              to join invite-only channels.

        If the <client mode mask> was not provided this command merely
        returns the mode mask to the client.


        Reply messages to the command:

        Max Arguments:  2
            Arguments:  (1) <Status Payload>  (2) <client mode mask>

        This command replies with the changed client mode mask that
        the client MUST to keep locally.


        Status messages:

            SILC_STATUS_OK
            SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
            SILC_STATUS_ERR_TOO_MANY_PARAMS
            SILC_STATUS_ERR_NOT_REGISTERED
            SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
            SILC_STATUS_ERR_BAD_CLIENT_ID
            SILC_STATUS_ERR_NOT_YOU
            SILC_STATUS_ERR_PERM_DENIED
            SILC_STATUS_ERR_UNKNOWN_MODE
            SILC_STATUS_ERR_NO_CLIENT_ID


   17   SILC_COMMAND_CMODE

        Max Arguments:  9
            Arguments:  (1) <Channel ID>      (2) [<channel mode mask>]
                        (3) [<user limit>]    (4) [<passphrase>]
                        (5) [<cipher>]        (6) [<hmac>]
                        (7) [<auth payload>]  (8) [<founder pubkey>]
                        (9) [<channel pubkey>]

        This command is used by client to set or change channel flags on
        a channel.  Channel has several modes that set various properties
        of a channel.  Modes may be masked together by ORing them thus
        having several modes set.  The <Channel ID> is the ID of the
        target channel.  The client changing channel mode MUST be on
        the same channel and posses sufficient privileges to be able to
        change the mode.

        When the mode is changed SILC_NOTIFY_TYPE_CMODE_CHANGE notify
        type MUST be distributed to the channel.

        The following channel modes are defined:

           0x00000000    SILC_CMODE_NONE

              No specific mode on channel.  This is the default when
              channel is created.  This means that channel is just plain
              normal channel.


           0x00000001    SILC_CMODE_PRIVATE

              Channel is private channel.  Private channels are shown
              in the channel list listed with SILC_COMMAND_LIST command
              with indication that the channel is private.  Also,
              client on private channel will no be detected to be on
              the channel as the channel is not shown in the client's
              currently joined channel list.  Channel founder and
              channel operator MAY set/unset this mode.


           0x00000002    SILC_CMODE_SECRET

              Channel is secret channel.  Secret channels are not shown
              in the list listed with SILC_COMMAND_LIST command.  Secret
              channels can be considered to be invisible channels.
              Channel founder and channel operator MAY set/unset this
              mode.


           0x00000004    SILC_CMODE_PRIVKEY

              Channel uses private channel key to protect the traffic
              on the channel.  When this mode is set the client will be
              responsible to set the key it wants to use to encrypt and
              decrypt the traffic on channel.  Server generated channel
              keys are not used at all.  This mode provides additional
              security as clients on channel may agree to use private
              channel key that even servers do not know.  Naturally,
              this requires that every client on the channel knows
              the key before hand (it is considered to be pre-shared-
              key).  The key material SHOULD be processed as stated
              in the [SILC3] in the section Processing the Key Material.

              As it is local setting it is possible to have several
              private channel keys on one channel.  In this case several
              clients can talk on same channel but only those clients
              that share the key with the message sender will be able
              to hear the talking.  Client SHOULD NOT display those
              message for the end user that it is not able to decrypt
              when this mode is set.

              Only channel founder MAY set/unset this mode.  If this
              mode is unset the server will distribute new channel
              key to all clients on the channel which will be used
              thereafter.


           0x00000008    SILC_CMODE_INVITE

              Channel is invite only channel.  Client may join to this
              channel only if it is invited to the channel.  Channel
              founder and channel operator MAY set/unset this mode.


           0x00000010    SILC_CMODE_TOPIC

              The topic of the channel may only be set by client that
              is channel founder or channel operator.  Normal clients
              on channel will not be able to set topic when this mode
              is set.  Channel founder and channel operator MAY set/
              unset this mode.


           0x00000020    SILC_CMODE_ULIMIT

              User limit has been set to the channel.  New clients
              may not join to the channel when the limit set is
              reached.  Channel founder and channel operator MAY set/
              unset the limit.  The <user limit> argument is the
              number of limited users.


           0x00000040    SILC_CMODE_PASSPHRASE

              Passphrase has been set to the channel.  Client may
              join to the channel only if it is able to provide the
              correct passphrase.  Setting passphrases to channel
              is entirely safe as all commands are protected in the
              SILC network.  Only channel founder MAY set/unset
              the passphrase.  The <passphrase> argument is the
              set passphrase.


           0x00000080    SILC_CMODE_CIPHER

              Sets specific cipher to be used to protect channel
              traffic.  The <cipher> argument is the requested cipher.
              When set or unset the server must re-generate new
              channel key.  Only channel founder MAY set the cipher of
              the channel.  When unset the new key is generated using
              default cipher for the channel.


           0x00000100    SILC_CMODE_HMAC

              Sets specific hmac to be used to compute the MACs of the
              channel message.  The <hmac> argument is the requested hmac.
              Only channel founder may set the hmac of the channel.


           0x00000200    SILC_CMODE_FOUNDER_AUTH

              Channel founder may set this mode to be able to regain
              channel founder rights even if the client leaves the
              channel.  The <auth payload> is the Authentication Payload
              consisting of the public key authentication method and the
              digital signature for that method.  The passphrase or NONE
              authentication methods MUST NOT be accepted.

              The server does not save <auth payload> but MUST verify it.
              The public key used to verify the payload is the <founder
              pubkey> if present, or the public key of the client sending
              this command.  If <founder pubkey> is present also that
              public key MUST be saved as founder's public key.  This
              mode may be set only if the <auth payload> was verified
              successfully.  The hash function used with the <auth
              payload> is selected by user or SHA1 otherwise.

              The public key of the founder is sent in the
              SILC_NOTIFY_TYPE_CMODE_CHANGE notify type so that other
              routers and servers in the network may save the public key.
              This way the founder can reclaim the founder rights back
              to the channel from any server in the network.  The founder
              rights can be regained by the SILC_CUMODE_FOUNDER channel
              user mode, or during joining procedure with the command
              SILC_COMMAND_JOIN.

              If this mode is already set but the <founder pubkey> is
              different the new key will replace the old founder key and
              the new key is distributed in the network with the
              SILC_NOTIFY_TYPE_CMODE_CHANGE notify.  Only the original
              founder may set this mode multiple times and the client
              MUST have SILC_CUMODE_FOUNDER mode on the channel.

              When this channel mode is set the channel also becomes
              permanent.  If all clients leave the channel while this
              mode is set the channel MUST NOT be destroyed.  The founder
              can reclaim the founder mode back on these empty channels
              at any time.  Implementations MAY limit the number of how
              many channels a user can own and how long they remain
              persistent.


           0x00000400    SILC_CMODE_SILENCE_USERS

              Channel founder may set this mode to silence normal users
              on the channel.  Users with operator privileges are not
              affected by this mode.  Messages sent by normal users
              are dropped by servers when this mode is set.  This mode
              can be used to moderate the channel.  Only channel founder
              may set/unset this mode.


           0x00000800    SILC_CMODE_SILENCE_OPERS

              Channel founder may set this mode to silence operators
              on the channel.  When used with SILC_CMODE_SILENCE_USERS
              mode this can be used to set the channel in state where only
              the founder of the channel may send messages to the channel.
              Messages sent by operators are dropped by servers when this
              mode is set.  Only channel founder may set/unset this mode.


           0x00001000    SILC_CMODE_CHANNEL_AUTH

              When this mode is set the channel has one or more public keys
              or certificates set, and ability to join the channel requires
              a client to provide digital signature that can be successfully
              verified with one of the channel public keys.  This mode is
              equivalent to the SILC_MODE_PASSPHRASE except that digital
              signatures are used to gain access to the channel.  Both
              modes MAY be set at the same time.  Channel founder may set
              and unset this mode.

              The <channel pubkey> argument is an Argument List Payload
              where each argument is Public Key Payload including public
              key to be added or removed from the channel public key list.
              To add a public key to channel this mode is set and the
              argument type is 0x00, and the argument is the public key.
              To remove a public key from channel public key list the
              argument type is 0x01, and the argument is the public key
              to be removed from the list.  To remove all public keys at
              once this mode is unset.  An implementation MAY limit the
              number of public keys that can be set for the channel.
              This mode MUST NOT be set if <channel pubkey> is not present
              when the mode is set for the first time.  Implementation MAY
              add and remove multiple public keys at the same time by
              including multiple arguments to the <channel pubkey>
              Argument List Payload.


        To make the mode system work, client MUST keep the channel mode
        mask locally so that the mode setting and unsetting would work
        without problems.  The client receives the initial channel mode
        mask when it joins to the channel.  When the mode changes on
        channel the server MUST distribute the changed channel mode mask
        to all clients on the channel by sending the notify type
        SILC_NOTIFY_TYPE_CMODE_CHANGE.  The notify type MUST also be sent
        to the server's primary router.  If the <channel mode mask> was
        not provided this command returns the mode mask, founder key,
        channel public key list and the current user limit to the client.

        Reply messages to the command:

        Max Arguments:  6
            Arguments:  (1) <Status Payload>    (2) <Channel ID>
                        (3) <channel mode mask> (4) [<founder pubkey>]
                        (5) [<channel pubkeys>] (6) [<user limit>]

        This command replies with the changed channel mode mask that
        client MUST keep locally.  It may also return the channel
        founder's public key if it is set.  It may also return list of
        channel public keys when the list was altered.  The <channel
        pubkeys> is Argument List Payload and each argument includes
        one public key.  The <user limit> is the current user limit
        on the channel, if one is set.

        Status messages:

            SILC_STATUS_OK
            SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
            SILC_STATUS_ERR_TOO_MANY_PARAMS
            SILC_STATUS_ERR_NOT_REGISTERED
            SILC_STATUS_ERR_NOT_ON_CHANNEL
            SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
            SILC_STATUS_ERR_BAD_CHANNEL_ID
            SILC_STATUS_ERR_NO_CHANNEL_ID
            SILC_STATUS_ERR_NO_CHANNEL_PRIV
            SILC_STATUS_ERR_NO_CHANNEL_FOPRIV
            SILC_STATUS_ERR_UNKNOWN_MODE
            SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
            SILC_STATUS_ERR_AUTH_FAILED


   18   SILC_COMMAND_CUMODE

        Max Arguments:  4
            Arguments:  (1) <Channel ID>    (2) <mode mask>
                        (3) <Client ID>     (4) [<auth payload>]

        This command is used by client to change channel user modes on
        channel.  Users on channel may have some special modes and this
        command is used by channel operators to set or change these modes.
        The <Channel ID> is the ID of the target channel.  The <mode mask>
        is OR'ed mask of modes.  The <Client ID> is the target client.
        The client changing channel user modes MUST be on the same channel
        as the target client and posses sufficient privileges to be able to
        change the mode.

        When the mode is changed SILC_NOTIFY_TYPE_CUMODE_CHANGE notify
        type is distributed to the channel.

        The following channel modes are defined:

           0x00000000    SILC_CUMODE_NONE

              No specific mode.  This is the normal situation for client.
              Also, this is the mode set when removing all modes from
              the target client.


           0x00000001    SILC_CUMODE_FOUNDER

              The client is channel founder of the channel.  Usually this
              mode is set only by the server when the channel was created.
              However, if the SILC_CMODE_FOUNDER_AUTH channel mode has
              been set, the client can claim channel founder privileges
              by providing the <auth payload> that the server will use
              to authenticate the client.  The public key that server will
              use to verify the <auth payload> MUST be the same public key
              that was saved when the SILC_CMODE_FOUNDER_AUTH channel
              mode was set.  The client MAY remove this mode at any time.


           0x00000002    SILC_CUMODE_OPERATOR

              Sets channel operator privileges on the channel for a
              client on the channel.  Channel founder and channel operator
              MAY set/unset this mode.  The client MAY remove this mode
              at any time.


           0x00000004    SILC_CUMODE_BLOCK_MESSAGES

              Marks that the client wishes not to receive any channel
              messages sent for the channel.  Client MAY set and unset
              this mode to itself.  Client MUST NOT set it to anyone else.
              When this mode is set server MUST NOT deliver channel
              messages to this client.  Other packets such as channel
              key packets are still sent to the client.

              A separate service could provide additional filtering
              features for accepting channel messages from certain
              sender.  However, this document does not specify such
              service.


           0x00000008    SILC_CUMODE_BLOCK_MESSAGES_USERS

              Marks that the client wishes not to receive any channel
              messages sent from normal users.  Only messages sent by
              channel founder or channel operator is accepted.  Client
              MAY set and unset this mode to itself.  Client MUST NOT
              set it to anyone else.  When this mode is set server MUST
              NOT deliver channel messages that are sent by normal users
              to this client.

              A separate service could provide additional filtering
              features for accepting channel messages from certain
              sender.  However, this document does not specify such
              service.


           0x00000010    SILC_CUMODE_BLOCK_MESSAGES_ROBOTS

              Marks that the client wishes not to receive any channel
              messages sent from robots.  Messages sent by users with
              the SILC_UMODE_ROBOT user mode set are not delivered.
              Client MAY set and unset this mode to itself.  Client MUST
              NOT set it to anyone else.  When this mode is set server
              MUST NOT deliver channel messages that are sent by robots
              to this client.


           0x00000020    SILC_CUMODE_QUIET

              Marks that the client cannot talk on the channel.  This
              mode can be set by channel operator or channel founder to
              some other user that is not operator or founder.  The
              target client MUST NOT unset this mode.  When this mode
              is set the server MUST drop messages sent by this client
              to the channel.


        Reply messages to the command:

        Max Arguments:  4
            Arguments:  (1) <Status Payload>  (2) <channel user mode mask>
                        (3) <Channel ID>      (4) <Client ID>

        This command replies with the changed channel user mode mask that
        client MUST keep locally. The <Channel ID> is the specified
        channel.  The <Client ID> is the target client.

        Status messages:

            SILC_STATUS_OK
            SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
            SILC_STATUS_ERR_TOO_MANY_PARAMS
            SILC_STATUS_ERR_NOT_REGISTERED
            SILC_STATUS_ERR_NOT_ON_CHANNEL
            SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
            SILC_STATUS_ERR_BAD_CHANNEL_ID
            SILC_STATUS_ERR_NO_CHANNEL_ID
            SILC_STATUS_ERR_NO_CHANNEL_PRIV
            SILC_STATUS_ERR_NO_CHANNEL_FOPRIV
            SILC_STATUS_ERR_UNKNOWN_MODE
            SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
            SILC_STATUS_ERR_AUTH_FAILED


   19   SILC_COMMAND_KICK

        Max Arguments:  3
            Arguments:  (1) <Channel ID>      (2) <Client ID>
                        (3) [<comment>]

        This command is used by channel operators to remove a client from
        channel.  The <channel> argument is the channel the client to be
        removed is on currently.  Note that the "kicker" must be on the same
        channel.  If <comment> is provided it will be sent to the removed
        client.

        After kicking the client the server MUST send the notify type
        SILC_NOTIFY_TYPE_KICKED to the channel and to its primary router.
        The client is removed from the channel after sending this notify.
        The kicked client MUST be removed from the invite list of the
        channel if it is explicitly added in the list.  The channel key
        MUST also be re-generated after kicking, unless the
        SILC_CMODE_PRIVKEY mode is set.

        Reply messages to the command:

        Max Arguments:  3
            Arguments:  (1) <Status Payload>  (2) <Channel ID>
                        (3) <Client ID>

        This command returns the Channel ID and Client ID that was kicked
        from the channel.

        Status messages:

            SILC_STATUS_OK
            SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
            SILC_STATUS_ERR_TOO_MANY_PARAMS
            SILC_STATUS_ERR_NOT_REGISTERED
            SILC_STATUS_ERR_NO_SUCH_CHANNEL
            SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
            SILC_STATUS_ERR_NO_CHANNEL_PRIV
            SILC_STATUS_ERR_NO_CLIENT_ID



   20   SILC_COMMAND_BAN

        Max Arguments:  3
            Arguments:  (1) <Channel ID>         (2) [<add | del>]
                        (3) [<ban list>]

        This command is used to manage the ban list of the channel
        indicated by the <Channel ID>.  A client that is banned from
        channel is no longer able to join the channel.  The client which
        is executing this command MUST have at least channel operator
        privileges on the channel.

        The <add | del> is an argument of size of 1 byte where 0x00 means
        adding a client to ban list, and 0x01 means deleting a client
        from ban list.  The <ban list>, if present, indicates the
        information to be added to or removed from the ban list.  It
        may include a string for matching clients, public key of a
        client (Public Key Payload) or Client ID of a client.  The
        <ban list> is an Argument List Payload.

        The following Argument Types has been defined for ban list
        Argument Payloads:

          0x01 - Argument is an ban string of following format:

            [<nickname>[@<server>]!][<username>]@[<hostname or IP/MASK>]

            The <hostname> may also be in format of IP/MASK to indicate
            a network.

          0x02 - Argument is the public key of a client
          0x03 - Argument is the Client ID of a client

        If unknown type value is received or there is invalid amount of
        Argument Payloads present in the list, the command MUST be
        discarded.  When argument that is to be deleted from the ban
        list does not exist in the list the argument is ignored.

        The server MUST send the notify type SILC_NOTIFY_TYPE_BAN to its
        primary router after adding to or removing from the ban list.
        The wildcards MAY be used with this command.  If this command
        is executed without the ban arguments the command merely replies
        with the current ban list.

        Reply messages to the command:

        Max Arguments:  3
            Arguments:  (1) <Status Payload>  (2) <Channel ID>
                        (3) [<ban list>]

        This command replies with the <Channel ID> of the channel and
        the current <ban list> of the channel if it exists.

        Status messages:

            SILC_STATUS_OK
            SILC_STATUS_ERR_NOT_REGISTERED
            SILC_STATUS_ERR_TOO_MANY_PARAMS
            SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
            SILC_STATUS_ERR_NO_CHANNEL_ID
            SILC_STATUS_ERR_NOT_ON_CHANNEL
            SILC_STATUS_ERR_NO_CHANNEL_PRIV
            SILC_STATUS_ERR_RESOURCE_LIMIT




   21   SILC_COMMAND_DETACH

        Max Arguments:  0
            Arguments:

        This command is used to detach from the network.  Client can
        send this command to its server to indicate that it will be
        detached.  By detaching the client remains in the network but
        the actual network connection to the server is closed.  The
        client may then later resume the old session back.

        When this command is received the server MUST check that the
        client is locally connected client, and set the user mode
        SILC_UMODE_DETACHED flag.  The SILC_NOTIFY_TYPE_UMODE_CHANGE
        MUST be also sent to routers.  The server then sends command
        reply to this command and closes the network connection.
        The server MUST NOT remove the client from its lists, or send
        any signoff notifications for this client.  See the [SILC1]
        for detailed information about detaching.

        Reply messages to the command:

        Max Arguments:  1
            Arguments:  (1) <Status Payload>

        This command replies only with the status indication.

        Status messages:

            SILC_STATUS_OK
            SILC_STATUS_ERR_NOT_REGISTERED



   22   SILC_COMMAND_WATCH

        Max Arguments:  4
            Arguments:  (1) <Client ID>       (2) [<add nickname>]
                        (3) [<del nickname>]  (4) [<public key>]

        This command is used to set up a watch for <add nickname>
        nickname.  When a user in the network appears with the
        nickname, or signoffs the network or user's mode is changed
        the client which set up the watch will be notified about
        this change.  This can be used to watch for certain nicknames
        in the network and receive notifications when for example a
        friend appears in the network or leaves the network.

        The <del nickname> is a nickname that has been previously
        added to watch list and is now removed from it.  Notifications
        for that nickname will not be delivered anymore.  The nickname
        set to watch MUST NOT include any wildcards.  Note also that a
        nickname may match several users since nicknames are not unique.
        Implementations MAY set limits for how many nicknames client
        can watch.

        OPTIONALLY this command may also be set to watch clients' actions
        in the network using their public key or certificate.  The
        <public key> MAY be present, and it is an Argument List Payload
        where each argument is a Public Key Payload including public key
        to be added or removed from the watch list.  To To add a public
        key to watch list the argument type is 0x00, and the argument is
        the public key.  To remove a public key from watch list list the
        argument type is 0x01, and the argument is the public key to be
        removed from the list.  An implementation MAY limit the number of
        public keys that can be set on the watch list.  Implementation MAY
        add and remove multiple public keys at the same time by including
        multiple arguments to the <public key> Argument List Payload.

        The <Client ID> is the Client ID of the sender of this command.

        When normal server receives this command from client it
        MUST send it to its router.  Router will process the command
        and actually keeps the watch list.

        Reply messages to the command:

        Max Arguments:  1
            Arguments:  (1) <Status Payload>

        This command replies only with the status indication.

        Status messages:

            SILC_STATUS_OK
            SILC_STATUS_ERR_NOT_REGISTERED
            SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
            SILC_STATUS_ERR_TOO_MANY_PARAMS
            SILC_STATUS_ERR_BAD_NICKNAME
            SILC_STATUS_ERR_WILDCARDS
            SILC_STATUS_ERR_RESOURCE_LIMIT
            SILC_STATUS_ERR_NO_SUCH_NICK
            SILC_STATUS_ERR_NICKNAME_IN_USE


   23   SILC_COMMAND_SILCOPER

        Max Arguments:  2
            Arguments:  (1) <username>  (2) <authentication payload>

        This command is used by normal client to obtain router operator
        privileges (also known as SILC operator) on the router.  Note
        that router operator has privileges that supersedes the server
        operator privileges.

        The <username> is the username set in the server configurations
        as operator.  The <authentication payload> is the data that the
        client is authenticated against.  It may be passphrase prompted
        for user on client's screen or it may be public key or certificate
        authentication data (data signed with private key).  The public
        key that router will use to verify the signature found in the
        payload should be verified.  It is recommended that the public
        key is saved locally in the router and router would not use
        any public keys received during the SKE.

        Difference between router operator and server operator is that
        router operator is able to handle cell level properties while
        server operator (even on router server) is able to handle only
        local properties, such as, local connections and normal server
        administration.  The router operator is also able to use the
        SILC_COMMAND_KILL command.

        After changing the mode server MUST send the notify type
        SILC_NOTIFY_TYPE_UMODE_CHANGE to its primary router.

        Reply messages to the command:

        Max Arguments:  1
            Arguments:  (1) <Status Payload>

        This command replies only with Status Payload.

        Status messages:

            SILC_STATUS_OK
            SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
            SILC_STATUS_ERR_TOO_MANY_PARAMS
            SILC_STATUS_ERR_NOT_REGISTERED
            SILC_STATUS_ERR_AUTH_FAILED




   24   SILC_COMMAND_LEAVE

        Max Arguments:  1
            Arguments:  (1) <Channel ID>

        This command is used by client to leave a channel the client is
        joined to.

        When leaving channel the server MUST send the notify type
        SILC_NOTIFY_TYPE_LEAVE to its primary router and to the channel.
        The channel key MUST also be re-generated when leaving the channel
        and distribute it to all clients still currently on the channel.
        The key MUST NOT be re-generated if the SILC_CMODE_PRIVKEY mode
        is set.

        Reply messages to the command:

        Max Arguments:  2
            Arguments:  (1) <Status Payload>  (2) <Channel ID>

        The <Channel ID> is the ID of left channel.

        Status messages:

            SILC_STATUS_OK
            SILC_STATUS_ERR_NOT_REGISTERED
            SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
            SILC_STATUS_ERR_TOO_MANY_PARAMS
            SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
            SILC_STATUS_ERR_BAD_CHANNEL_ID
            SILC_STATUS_ERR_NO_CHANNEL_ID


   25   SILC_COMMAND_USERS

        Max Arguments:  2
            Arguments:  (1) [<Channel ID>]  (2) [<channel name>]

        This command is used to list user names currently on the requested
        channel; either the argument <Channel ID> or the <channel name>.
        One of these arguments must be present.  The server MUST resolve
        the joined clients and reply with a lists of users on the channel
        and with list of user modes on the channel.

        If the requested channel is a private or secret channel, this
        command MUST NOT send the list of users, except if the sender is
        on the channel, or the sender is a server.  Otherwise, error is
        returned to the sender.

        Reply messages to the command:

        Max Arguments:  5
            Arguments:  (1) <Status Payload>  (2) <Channel ID>
                        (3) <list count>      (4) <Client ID list>
                        (5) <client mode list>

        This command replies with the Channel ID of the requested channel
        Client ID list of the users on the channel and list of their modes.
        The Client ID list has Client ID's of all users in the list.  The
        <Client ID list> is formed by adding Client ID's one after another.
        The <client mode list> is formed by adding client's user modes on
        the channel one after another (4 bytes (32 bits) each).  The <list
        count> of length of 4 bytes (32 bits), tells the number of entries
        in the lists.  Both lists MUST have equal number of entries.

        Status messages:

            SILC_STATUS_OK
            SILC_STATUS_ERR_NOT_REGISTERED
            SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
            SILC_STATUS_ERR_TOO_MANY_PARAMS
            SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
            SILC_STATUS_ERR_BAD_CHANNEL_ID
            SILC_STATUS_ERR_NO_CHANNEL_ID
            SILC_STATUS_ERR_NOT_ON_CHANNEL


   26   SILC_COMMAND_GETKEY

        Max Arguments:  1
            Arguments:  (1) <ID Payload>

        This command is used to fetch the public key of the client or
        server indicated by the <ID Payload>.  The public key is fetched
        from the server where to the client is connected.

        Reply messages to the command:

        Max Arguments:  3
            Arguments:  (1) <Status Payload>      (2) <ID Payload>
                        (3) [<Public Key Payload>]

        This command replies with the client's or server's ID and with
        the <Public Key Payload>.

        Status messages:

            SILC_STATUS_OK
            SILC_STATUS_ERR_NOT_REGISTERED
            SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
            SILC_STATUS_ERR_TOO_MANY_PARAMS
            SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
            SILC_STATUS_ERR_NO_SUCH_SERVER_ID


   27   SILC_COMMAND_SERVICE

        Max Arguments:  256
            Arguments:  (1) [<service name>]    (2) [<auth payload>]
                        (n) [...]

        This command is used to negotiate a service agreement with a
        remote server.  If this command is given without arguments it
        MAY return the service list, if it is publicly available.  The
        <service name> is a service specific identifier, and the
        <auth payload> MAY be used to authenticate the requester to the
        remote service.  The authentication to a service may be based
        on previous agreement with the requester and the service
        provider.  The command MAY also take additional service
        specific arguments.

        This document does not specify any services.  How the services
        are configured and put available in a server is also out of
        scope of this document.

        This command MAY be used by client to start using some service
        in a server, but it also MAY be used by server to negotiate
        to start using a service in some other server or router.

        After the negotiation is done both of the parties need to know
        from the service identifier how the service can be used.  The
        service can be considered to be a protocol which both of the
        parties need to support.

        Reply messages to the command:

        Max Arguments:  256
            Arguments:  (1) <Status Payload>      (2) [<service list>]
                        (3) [<service name>]      (n) [...]


        This command MAY reply with the <service list> when command is
        given without arguments, and the list is a comma separated list
        of service identifiers.  The <service name> is the service that
        the sender requested and this is provided when the server has
        accepted the sender to use the <service name>.  The command
        reply MAY also have additional service specific arguments.

        Status messages:

            SILC_STATUS_OK
            SILC_STATUS_ERR_NOT_REGISTERED
            SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
            SILC_STATUS_ERR_TOO_MANY_PARAMS
            SILC_STATUS_ERR_NO_SUCH_SERVICE
            SILC_STATUS_ERR_AUTH_FAILED
            SILC_STATUS_ERR_PERM_DENIED



   28 - 199

        Currently undefined commands.


   200 - 254

        These commands are reserved for private use and will not be defined
        in this document.


   255  SILC_COMMAND_MAX

        Reserved command.  This must not be sent.
.in 3


.ti 0
2.4 SILC Command Status Payload

Command Status Payload is sent in command reply messages to indicate
the status of the command.  The payload is one of argument in the
command thus this is the data area in Command Argument Payload described
in [SILC2].  The payload is only 2 bytes in length.  The following
diagram represents the Command Status Payload (fields are always in
MSB first order).


.in 21
.nf
                     1
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|     Status    |     Error     |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
.in 3

.ce
Figure 6:  SILC Command Status Payload


.in 6
o Status (1 byte) - Indicates the status message type,
  error, start of list, entry of list or end of list.

o Error (1 byte) - Indicates the error if the Status
  field is some list status, which means there are list
  of errors.
.in 3

The values in Status and Error fields are set according
the following rules:

.in 6
o If there is single reply and error has not occurred
  then Status field includes value SILC_STATUS_OK, and
  the Error field MUST be ignored (and set to zero
  value).

o If there is single error, then Status field includes
  one of the error values, and the Error field MUST be
  ignored (and set to zero value).

o If there will be multiple successful command replies
  then Status field includes SILC_STATUS_LIST_START,
  SILC_STATUS_LIST_ITEM or SILC_STATUS_LIST_END value,
  and Error field is set to SILC_STATUS_OK.

o If there are multiple error replies then Status field
  includes SILC_STATUS_LIST_START, SILC_STATUS_LIST_ITEM
  or SILC_STATUS_LIST_END value, and the Error field
  includes the error value.
.in 3

This way it is possible to send single successful or
single error reply, but also multiple successful and
multiple error replies.  Note that it is possible to
send both list of successful replies and list of error
replies at the same time, however in this case the
list of error replies MUST be sent after the successful
replies.  This way the recipient may ignore the multiple
errors if it wishes to do so.  Also note that in this
case the successful and error replies belong to the
same list.

All Status messages are described in the next section.


.ti 0
3 SILC Status Types

Status messages are returned in SILC protocol in command reply
packet and in notify packet.  The SILC_PACKET_COMMAND_REPLY is
the command reply packet and status types are sent inside the
Status Payload as one of command reply argument, as defined in
previous sections.  For SILC_PACKET_NOTIFY packet they can be sent
as defined in [SILC2] for SILC_NOTIFY_TYPE_ERROR type.  The same
types defined in this section are used in both cases.

When returning status messages in the command reply message they
indicate whether the command was executed without errors.  If error
occurred the status indicates which error occurred.  If error
occurred the arguments to the command replies are dictated by the
error type.  If arguments are to be sent, they are defined below
with the error status types.

When sending status messages in SILC_NOTIFY_TYPE_ERROR notify type
they always send some error status.  Usually they are sent to
indicate that error occurred while processing some SILC packet.
Please see the [SILC1] and [SILC2] for more information sending
status types in SILC_NOTIFY_TYPE_ERROR notify.

The Status Types are only numeric values and the receiver must
convert the numeric values into human readable messages if this
is desired in the application.

List of all defined status types:

.in 0
   Generic status messages:

   0    SILC_STATUS_OK

        Ok status.  Everything went Ok.  The status payload maybe
        safely ignored in this case.

   1    SILC_STATUS_LIST_START

        Start of the list.  There will be several command replies and
        this reply is the start of the list.

   2    SILC_STATUS_LIST_ITEM

        Item in the list.  This is one of the item in the list but not the
        first or last one.

   3    SILC_STATUS_LIST_END

        End of the list.  There were several command replies and this
        reply is the last of the list.  There won't be other replies
        belonging to this list after this one.

   4 - 9

        Currently undefined and has been reserved for the future.


   Error status message:



   10   SILC_STATUS_ERR_NO_SUCH_NICK

        "No such nickname".  Requested nickname does not exist.
         The next argument MUST be the requested nickname.

   11   SILC_STATUS_ERR_NO_SUCH_CHANNEL

        "No such channel".  Requested channel name does not exist.
         The next argument MUST be the requested channel name.

   12   SILC_STATUS_ERR_NO_SUCH_SERVER

        "No such server".  Requested server name does not exist.
         The next argument MUST be the requested server name.

   13   SILC_STATUS_ERR_INCOMPLETE_INFORMATION

        "Incomplete registration information".  Information remote
        sent was incomplete.

   14   SILC_STATUS_ERR_NO_RECIPIENT

        "No recipient given".  Command required recipient which was
        not provided.

   15   SILC_STATUS_ERR_UNKNOWN_COMMAND

        "Unknown command".  Command sent to server is unknown by the
        server.

   16   SILC_STATUS_ERR_WILDCARDS

        "Wildcards cannot be used".  Wildcards were provided but they
        weren't permitted.

   17   SILC_STATUS_ERR_NO_CLIENT_ID

        "No Client ID given".  Client ID were expected as command
        parameter but were not found.

   18   SILC_STATUS_ERR_NO_CHANNEL_ID

        "No Channel ID given".  Channel ID were expected as command
        parameter but were not found.

   19   SILC_STATUS_ERR_NO_SERVER_ID

        "No Serve ID given".  Server ID were expected as command
        parameter but were not found.

   20   SILC_STATUS_ERR_BAD_CLIENT_ID

        "Bad Client ID".  Client ID provided were erroneous.
         The next argument MUST be the provided ID.

   21   SILC_STATUS_ERR_BAD_CHANNEL_ID

        "Bad Channel ID".  Channel ID provided were erroneous.
         The next argument MUST be the provided ID.

   22   SILC_STATUS_ERR_NO_SUCH_CLIENT_ID

        "No such Client ID".  Client ID provided does not exist.
        The unknown Client ID MUST be provided as next argument
        in the reply.

   23   SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID

        "No such Channel ID".  Channel ID provided does not exist.
        The unknown Channel ID MUST be provided as next argument
        in the reply.

   24   SILC_STATUS_ERR_NICKNAME_IN_USE

        "Nickname already exists".  Nickname created could not be
        registered because number of same nicknames were already set to
        maximum.  This is not expected to happen in real life but is
        possible to occur.

   25   SILC_STATUS_ERR_NOT_ON_CHANNEL

        "You are not on that channel".  The command were specified for
        channel user is not currently on.  The next argument MUST be the
        Channel ID.

   26   SILC_STATUS_ERR_USER_NOT_ON_CHANNEL

        "They are not on channel".  The requested target client is not
        on requested channel.  The next two arguments, in this order,
        MUST be the requested Client ID and Channel ID.

   27   SILC_STATUS_ERR_USER_ON_CHANNEL

        "User already on channel".  User were invited on channel they
        already are on.  The next two arguments, in this order, MUST be
        the  requested Client ID and Channel ID.

   28   SILC_STATUS_ERR_NOT_REGISTERED

        "You have not registered".  User executed command that requires
        the client to be registered on the server before it may be
        executed.

   29   SILC_STATUS_ERR_NOT_ENOUGH_PARAMS

        "Not enough parameters".  Command requires more parameters
        than provided.

   30   SILC_STATUS_ERR_TOO_MANY_PARAMS

        "Too many parameters".  Too many parameters were provided
        for the command.

   31   SILC_STATUS_ERR_PERM_DENIED

        "Permission denied".  Generic permission denied error status
        to indicate disallowed access.

   32   SILC_STATUS_ERR_BANNED_FROM_SERVER

        "You are banned from this server".  The client tried to register
        on server that has explicitly denied this host to connect.

   33   SILC_STATUS_ERR_BAD_PASSWORD

        "Cannot join channel. Incorrect password".  Password provided for
        channel were not accepted.  The next argument MUST be the
        Channel ID.

   34   SILC_STATUS_ERR_CHANNEL_IS_FULL

        "Cannot join channel. Channel is full".  The channel is full
        and client cannot be joined to it.  The next argument MUST be
        the Channel ID.

   35   SILC_STATUS_ERR_NOT_INVITED

        "Cannot join channel. You have not been invited".  The channel
        is invite only channel and client has not been invited.  The next
        argument MUST be the Channel ID.

   36   SILC_STATUS_ERR_BANNED_FROM_CHANNEL

        "Cannot join channel. You have been banned".  The client has
        been banned from the channel.  The next argument MUST be the
        Channel ID.

   37   SILC_STATUS_ERR_UNKNOWN_MODE

        "Unknown mode".  Mode provided by the client were unknown to
        the server.

   38   SILC_STATUS_ERR_NOT_YOU

        "Cannot change mode for other users".  User tried to change
        someone else's mode.

   39   SILC_STATUS_ERR_NO_CHANNEL_PRIV

        "Permission denied. You are not channel operator".  Command may
        be executed only by channel operator.  The next argument MUST be
        the Channel ID.

   40   SILC_STATUS_ERR_NO_CHANNEL_FOPRIV

        "Permission denied. You are not channel founder".  Command may
        be executed only by channel operator.  The next argument MUST be
        the Channel ID.

   41   SILC_STATUS_ERR_NO_SERVER_PRIV

        "Permission denied. You are not server operator".  Command may
        be executed only by server operator.

   42   SILC_STATUS_ERR_NO_ROUTER_PRIV

        "Permission denied. You are not SILC operator".  Command may be
        executed only by router (SILC) operator.

   43   SILC_STATUS_ERR_BAD_NICKNAME

        "Bad nickname".  Nickname requested contained illegal characters
        or were malformed.

   44   SILC_STATUS_ERR_BAD_CHANNEL

        "Bad channel name".  Channel requested contained illegal characters
        or were malformed.

   45   SILC_STATUS_ERR_AUTH_FAILED

        "Authentication failed".  The authentication data sent as
        argument were wrong and thus authentication failed.

   46   SILC_STATUS_ERR_UNKOWN_ALGORITHM

        "The algorithm was not supported."  The server does not support the
        requested algorithm.  The next argument MUST be the algorithm name
        string.

   47   SILC_STATUS_ERR_NO_SUCH_SERVER_ID

        "No such Server ID".  Server ID provided does not exist.
        The unknown Server ID MUST be provided as next argument
        in the reply.

   48   SILC_STATUS_ERR_RESOURCE_LIMIT

        "No more resources available".  This can mean that server cannot
        or will not accept something due to resource limitations.

   49   SILC_STATUS_ERR_NO_SUCH_SERVICE

        "Service does not exist".  Requested service identifier is
        unknown.  The next argument MUST be the service identifier.

   50   SILC_STATUS_ERR_NOT_AUTHENTICATED

        "You have not been authenticated".  Remote connection is not
        authenticated even though it is supposed to be.

   51   SILC_STATUS_ERR_BAD_SERVER_ID

        "Server ID is not valid".  Provided server ID is not valid.
        The next argument MUST be the provided ID.

   52   SILC_STATUS_ERR_KEY_EXCHANGE_FAILED

        "Key exchange failed".  Key Exchange protocol failed.

   53   SILC_STATUS_ERR_BAD_VERSION

        "Bad version".  Protocol or software version mismatch.

   54   SILC_STATUS_ERR_TIMEDOUT

        "Operation timed out".  Operation or service request timed
        out, and thus was not processed.

   55   SILC_STATUS_ERR_UNSUPPORTED_PUBLIC_KEY

        "Unsupported public key type".  The public key or certificate
        type is not supported in this implementation.

   56   SILC_STATUS_ERR_OPERATION_ALLOWED

        "Operation is not allowed".  A operation, for example a command,
        is not allowed or it's execution is not allowed.

.in 3



.ti 0
4 Security Considerations

Security is central to the design of this protocol, and these security
considerations permeate the specification.  Common security considerations
such as keeping private keys truly private and using adequate lengths for
symmetric and asymmetric keys must be followed in order to maintain the
security of this protocol.


.ti 0
5 References

[SILC1]      Riikonen, P., "Secure Internet Live Conferencing (SILC),
             Protocol Specification", Internet Draft, January 2007.

[SILC2]      Riikonen, P., "SILC Packet Protocol", Internet Draft,
             January 2007.

[SILC3]      Riikonen, P., "SILC Key Exchange and Authentication
             Protocols", Internet Draft, January 2007.

[IRC]        Oikarinen, J., and Reed D., "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-CLIENT] Kalt, C., "Internet Relay Chat: Client Protocol", RFC
             2812, April 2000.

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

[SSH-TRANS]  Ylonen, T., et al, "SSH Transport Layer Protocol",
             Internet Draft.

[PGP]        Callas, J., et al, "OpenPGP Message Format", RFC 2440,
             November 1998.

[SPKI]       Ellison C., et al, "SPKI Certificate Theory", RFC 2693,
             September 1999.

[PKIX-Part1] Housley, R., et al, "Internet X.509 Public Key
             Infrastructure, Certificate and CRL Profile", RFC 2459,
             January 1999.

[Schneier]   Schneier, B., "Applied Cryptography Second Edition",
             John Wiley & Sons, New York, NY, 1996.

[Menezes]    Menezes, A., et al, "Handbook of Applied Cryptography",
             CRC Press 1997.

[OAKLEY]     Orman, H., "The OAKLEY Key Determination Protocol",
             RFC 2412, November 1998.

[ISAKMP]     Maughan D., et al, "Internet Security Association and
             Key Management Protocol (ISAKMP)", RFC 2408, November
             1998.

[IKE]        Harkins D., and Carrel D., "The Internet Key Exchange
             (IKE)", RFC 2409, November 1998.

[HMAC]       Krawczyk, H., "HMAC: Keyed-Hashing for Message
             Authentication", RFC 2104, February 1997.

[PKCS1]      Kalinski, B., and Staddon, J., "PKCS #1 RSA Cryptography
             Specifications, Version 2.0", RFC 2437, October 1998.

[RFC2119]    Bradner, S., "Key Words for use in RFCs to Indicate
             Requirement Levels", BCP 14, RFC 2119, March 1997.

[RFC3629]    Yergeau, F., "UTF-8, a transformation format of ISO
             10646", RFC 3629, November 2003.

[ATTRS]      Riikonen, P., "User Online Presence and Information
             Attributes", Internet Draft, May 2002.


.ti 0
6 Author's Address

.nf
Pekka Riikonen
Helsinki
Finland

EMail: priikone@iki.fi


.ti 0
Appendix A

This appendix defines the usage of the <Requested Attributes> argument in
the SILC_COMMAND_WHOIS command.  The attributes are defined in [ATTRS],
and may be used to request additional information about the user.  Since
the information that may be requested using the attributes is something
that server cannot deliver to the sender, it is possible to send the WHOIS
command directly to the destination client whom will then provide the
requested attributes.  This requires the servers to relay the WHOIS
command to the client, and it requires capability for handling the WHOIS
command in the client end.

The <Requested Attributes> MAY include several attributes that are
requested.  The format and encoding of the <Requested Attributes> is as
defined in [ATTRS].  When <Requested Attributes> argument is set the
server MAY process the attributes to see whether it can narrow down
the WHOIS search, for example when searching with a nickname.  The
normal servers MUST process the WHOIS command as normal WHOIS command,
that is to send the command directly to the router.  The router MAY
process the attributes, but it MUST send the command to the server
that owns the requested client.

The server that owns the client and receives the command MUST check
whether the client is detached from the network.  If it is detached,
that is the user mode has the SILC_UMODE_DETACHED mode set, it SHOULD
process the attributes and provide as many of the requested attributes
as possible and then send reply back to the sender.  If the client is
active in the network it MUST send the command to the client for
processing.

The client receiving WHOIS command SHOULD check whether the
<Requested Attributes> argument is set.  If it is not set then the
WHOIS command SHOULD be discarded.  The client processes the requested
attributes and SHOULD reply to each of the requested attribute with
either valid value, or with an indication that the requested attribute
is not known or supported.  This is to be done as defined in [ATTRS].
The client always MUST send a reply to the command when some attributes
were requested.  The client MAY also add additional attributes to the
reply even if they were not requested.  The client MAY also digitally
sign the attributes with ATTRIBUTE_USER_DIGITAL_SIGNATURE as defined
in [ATTRS].  Then the client sends the reply back to the sender of
the command.  The command reply that client assembles does not need
to include any other argument but the <Status Payload> (1), and the
<Attributes> (11).  The server receiving reply from client MUST allow
this sort of command reply for WHOIS command.

The information received from the client MAY be cached in the
server's end.  The caching may be desired for example if the client
can be detached from the network.  This way the server is then able
to provide at least partial information for a requester.  The
server MAY also process the command reply and verify whether the
attributes provided in the reply are actually valid.  If it can do
this, and verify that they indeed are valid values it MAY append
a digital signature at the end of the attributes with the
ATTRIBUTE_SERVER_DIGITAL_SIGNATURE as defined in [ATTRS].  The
server then MUST provide valid WHOIS command reply to the sender
of the command.   Other servers and routers that receive the command
reply en route to the original sender MAY also cache the information.

The client which receives the command reply to the WHOIS command
SHOULD verify the ATTRIBUTE_USER_DIGITAL_SIGNATURE and the
ATTRIBUTE_SERVER_DIGITAL_SIGNATURE if they are provided.


.ti 0
Full Copyright Statement

Copyright (C) The Internet Society (2007).

This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.

This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM 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.
