8 .ds RF FORMFEED[Page %]
12 .ds CH Secure Internet Live Conferencing
17 Network Working Group P. Riikonen
19 draft-riikonen-silc-spec-00.txt 27 June 2000
25 Secure Internet Live Conferencing (SILC),
26 Protocol Specification
31 This document is an Internet-Draft. Internet-Drafts are working
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48 The distribution of this memo is unlimited.
54 This memo describes a Secure Internet Live Conferencing (SILC)
55 protocol which provides secure conferencing services over insecure
56 network channel. SILC is IRC [IRC] like protocol, however, it is
57 not equivalent to IRC and does not support IRC. Strong cryptographic
58 methods are used to protect SILC packets inside SILC network. Two
59 other Internet Drafts relates very closely to this memo; SILC Packet
60 Protocol [SILC2] and SILC Key Exchange and Authentication Protocols
74 1 Introduction .................................................. 3
75 2 SILC Concepts ................................................. 3
76 2.1 SILC Network Topology ..................................... 4
77 2.2 Communication Inside a Cell ............................... 5
78 2.3 Communication in the Network .............................. 6
79 2.4 Channel Communication ..................................... 7
80 3 SILC Specification ............................................ 7
81 3.1 Client .................................................... 7
82 3.1.1 Client ID ........................................... 8
83 3.2 Server .................................................... 8
84 3.2.1 Server's Local ID List .............................. 9
85 3.2.2 Server ID ........................................... 10
86 3.2.3 SILC Server Ports ................................... 10
87 3.3 Router .................................................... 11
88 3.3.1 Router's Local ID List .............................. 11
89 3.3.2 Router's Global ID List ............................. 12
90 3.3.3 Router's Server ID .................................. 12
91 3.4 Channels .................................................. 12
92 3.4.1 Channel ID .......................................... 13
93 3.5 Operators ................................................. 14
94 3.6 SILC Commands ............................................. 14
95 3.7 SILC Packets .............................................. 15
96 3.8 Packet Encryption ......................................... 15
97 3.8.1 Determination of the Source and the Destination ..... 16
98 3.8.2 Client To Client .................................... 16
99 3.8.3 Client To Channel ................................... 17
100 3.8.4 Server To Server .................................... 18
101 3.9 Key Exchange And Authentication ........................... 18
102 3.10 Algorithms ............................................... 19
103 3.10.1 Ciphers ............................................ 19
104 3.10.2 Public Key Algorithms .............................. 20
105 3.10.3 MAC Algorithms ..................................... 20
106 3.10.4 Compression Algorithms ............................. 20
107 3.11 SILC Public Key .......................................... 21
108 4 SILC Procedures ............................................... 23
109 4.1 Creating Client Connection ................................ 23
110 4.2 Creating Server Connection ................................ 24
111 4.3 Joining to a Channel ...................................... 25
112 4.4 Channel Key Generation .................................... 26
113 4.5 Private Message Sending and Reception ..................... 27
114 4.6 Private Message Key Generation ............................ 27
115 4.7 Channel Message Sending and Reception ..................... 28
116 4.8 Session Key Regeneration .................................. 28
117 4.9 Command Sending and Reception ............................. 29
118 5 SILC Commands ................................................. 29
119 5.1 SILC Commands Syntax ...................................... 29
120 5.2 SILC Commands List ........................................ 31
121 5.3 SILC Command Status Types ................................. 53
122 5.3.1 SILC Command Status Payload ......................... 53
123 5.3.2 SILC Command Status List ............................ 54
124 6 Security Considerations ....................................... 58
125 7 References .................................................... 58
126 8 Author's Address .............................................. 59
133 Figure 1: SILC Network Topology
134 Figure 2: Communication Inside cell
135 Figure 3: Communication Between Cells
136 Figure 4: SILC Public Key
137 Figure 5: SILC Command Status Payload
143 This document describes a Secure Internet Live Conferencing (SILC)
144 protocol which provides secure conferencing services over insecure
145 network channel. SILC is IRC [IRC] like protocol, however, it is
146 not equivalent to IRC and does not support IRC. Strong cryptographic
147 methods are used to protect SILC packets inside SILC network. Two
148 other Internet Drafts relates very closely to this memo; SILC Packet
149 Protocol [SILC2] and SILC Key Exchange and Authentication Protocols
152 The protocol uses extensively packets as conferencing protocol
153 requires message and command sending. The SILC Packet Protocol is
154 described in [SILC2] and should be read to fully comprehend this
155 document and protocol. [SILC2] also describes the packet encryption
156 and decryption in detail.
158 The security of SILC protocol and for any security protocol for that
159 matter is based on strong and secure key exchange protocol. The SILC
160 Key Exchange protocol is described in [SILC3] along with connection
161 authentication protocol and should be read to fully comprehend this
162 document and protocol.
164 The SILC protocol has been developed to work on TCP/IP network
165 protocol, although it could be made to work on other network protocols
166 with only minor changes. However, it is recommended that TCP/IP
167 protocol is used under SILC protocol. Typical implementation would
168 be made in client-server model.
174 This section describes various SILC protocol concepts that forms the
175 actual protocol, and in the end, the actual SILC network. The mission
176 of the protocol is to deliver messages from clients to other clients
177 through routers and servers in secure manner. The messages may also
178 be delivered from one client to many clients forming a group, also
181 This section does not focus to security issues, instead basic network
182 concepts are introduced to make the topology of the SILC network
187 2.1 SILC Network Topology
189 SILC network is a cellular network as opposed to tree style network
190 topology. The rationale for this is to have servers that can perform
191 specific kind of tasks what other servers cannot perform. This leads
192 to two kinds of servers; normal SILC servers and SILC routers.
193 A difference between normal server and router server is that routers
194 knows everything about everything in the network. They also do the
195 actual routing of the messages to the correct receiver. Normal servers
196 knows only about local information and nothing about global information.
197 This makes the network faster as there are less servers that needs to
198 keep global information up to date at all time.
200 This, on the other hand, leads to cellular like network, where routers
201 are in the centrum on the cell and servers are connected to the router.
202 Following diagram represents SILC network topology.
207 ---- ---- ---- ---- ---- ----
208 | S8 | S5 | S4 | | S7 | S5 | S6 |
209 ----- ---- ----- ----- ---- -----
210 | S7 | S/R1 | S2 | --- | S8 | S/R2 | S4 |
211 ---- ------ ---- ---- ------ ----
212 | S6 | S3 | S1 | | S1 | S3 | S2 | ---- ----
213 ---- ---- ---- ---- ---- ---- | S3 | S1 |
214 Cell 1. \\ Cell 2. | \\____ ----- -----
216 ---- ---- ---- ---- ---- ---- ---- ------
217 | S7 | S4 | S2 | | S1 | S3 | S2 | | S2 | S5 |
218 ----- ---- ----- ----- ---- ----- ---- ----
219 | S6 | S/R3 | S1 | --- | S4 | S/R5 | S5 | Cell 4.
220 ---- ------ ---- ---- ------ ----
221 | S8 | S5 | S3 | | S6 | S7 | S8 | ... etc ...
222 ---- ---- ---- ---- ---- ----
227 Figure 1: SILC Network Topology
230 A cell is formed when a server or servers connect to one router. In
231 SILC network normal server cannot directly connect to other normal
232 server. Normal server may only connect to SILC router which then
233 routes the messages to the other servers in the cell. Router servers
234 on the other hand may connect to other routers to form the actual SILC
235 network, as seen in above figure. However, router is also normal SILC
236 server; clients may connect to it the same way as to normal SILC
237 servers. Normal server also cannot have active connections to more
238 than one router. Normal server cannot be connected to two different
239 cells. Router servers, on the other hand, may have as many router to
240 router connections as needed.
242 There are many issues in this network topology that needs to be careful
243 about. Issues like the size of the cells, the number of the routers in
244 the SILC network and the capacity requirements of the routers. These
245 issues should be discussed in the Internet Community and additional
246 documents on the issue will be written.
250 2.2 Communication Inside a Cell
252 It is always guaranteed that inside a cell message is delivered to the
253 recipient with at most two server hops. Client who is connected to
254 server in the cell and is talking on channel to other client connected
255 to other server in the same cell, will have its messages delivered from
256 its local server first to the router of the cell, and from the router
257 to the other server in the cell. Following diagram represents this
272 Figure 2: Communication Inside cell
275 Example: Client 1. connected to Server 1. message sent to
276 Client 4. connected to Server 2. travels from Server 1.
277 first to Router which routes the message to Server 2.
278 which then sends it to the Client 4. All the other
279 servers in the cell will not see the routed message.
282 If client is connected directly to the router, as router is also normal
283 SILC server, the messages inside the cell are always delivered only with
284 one server hop. If clients communicating with each other are connected
285 to the same server, no router interaction is needed. This is the optimal
286 situation of message delivery in the SILC network.
290 2.3 Communication in the Network
292 If the message is destined to server that does not belong to local cell
293 the message is routed to the router server to which the destination
294 server belongs, if the local router is connected to destination router.
295 If there is no direct connection to the destination router, the local
296 router routes the message to its primary route. Following diagram
297 represents message sending between cells.
302 1 --- S1 S4 --- 5 S2 --- 1
303 S/R - - - - - - - - S/R
313 Figure 3: Communication Between Cells
316 Example: Client 5. connected to Server 4. in Cell 1. message sent
317 to Client 2. connected to Server 1. in Cell 2. travels
318 from Server 4. to Router which routes the message to
319 Router in Cell 2, which then routes the message to
320 Server 1. All the other servers and routers in the
321 network will not see the routed message.
324 The optimal case of message delivery from client point of view is
325 when clients are connected directly to the routers and the messages
326 are delivered from one router to the other router.
333 2.4 Channel Communication
335 Messages may be sent to group of clients as well. Sending messages to
336 many clients works the same way as sending messages point to point, from
337 message delivery point of view. Security issues are another matter
338 which are not discussed in this section.
340 Router server handles the message routing to multiple recipients. If
341 any recipient is not in the same cell as the sender the messages are
344 Server distributes the channel message to its local clients who are
345 joined to the channel. Also, router distributes the message to its
346 local clients on the channel.
350 3. SILC Specification
352 This section describes the SILC protocol. However, [SILC2] and
353 [SILC3] describes other important protocols that are part of this SILC
354 specification and must be read.
360 A client is a piece of software connecting to SILC server. SILC client
361 cannot be SILC server. Purpose of clients is to provide the user
362 interface of the SILC services for end user. Clients are distinguished
363 from other clients by unique Client ID. Client ID is a 128 bit ID that
364 is used in the communication in the SILC network. The client ID is
365 based on the nickname selected by the user. User uses logical nicknames
366 in communication which are then mapped to the corresponding Client ID.
367 Client ID's are low level identifications and must not be seen by the
370 Clients provide other information about the end user as well. Information
371 such as the nickname of the user, username and the hostname of the end
372 user and user's real name. See section 3.2 Server for information of
373 the requirements of keeping this information.
375 The nickname selected by the user is not unique in the SILC network.
376 There can be 2^8 same nicknames for one IP address. As for comparison to
377 IRC [IRC] where nicknames are unique this is a fundamental difference
378 between SILC and IRC. This causes the server names to be used along
379 with the nicknames to identify specific users when sending messages.
380 This feature of SILC makes IRC style nickname-wars obsolete as no one
381 owns their nickname; there can always be someone else with the same
382 nickname. Another difference is that there are no limit of the length
383 of the nickname in the SILC.
389 Client ID is used to identify users in the SILC network. The Client ID
390 is unique to the extent that there can be 2^128 different Client ID's.
391 Collisions are not expected to happen. The Client ID is defined as
395 128 bit Client ID based on IPv4 addresses:
397 32 bit ServerID IP address (bits 1-32)
399 88 bit Truncated MD5 hash value of the nickname
401 o Server ID IP address - Indicates the server where this
402 client is coming from. The IP address hence equals the
403 server IP address where to the client has connected.
405 o Random number - Random number to further unify the
406 Client ID. This makes it possible to have 2^8 same
407 nicknames from the same server IP address.
409 o MD5 hash - MD5 hash value of the nickname is truncated
410 taking 88 bits from the start of the hash value. This
411 hash value is used to search the user's Client ID from
415 Collisions could occur when more than 2^8 clients using same nickname
416 from the same server IP address is connected to the SILC network.
417 Server must be able to handle this situation by refusing to accept
418 anymore of that nickname.
420 Another possible collision may happen with the truncated hash value of
421 the nickname. It could be possible to have same truncated hash value for
422 two different nicknames. However, this is not expected to happen nor
423 cause any problems if it would occur. Nicknames are usually logical and
424 it is unlikely to have two distinct logical nicknames produce same
425 truncated hash value.
431 Servers are the most important parts of the SILC network. They form the
432 basis of the SILC, providing a point to which clients may connect to.
433 There are two kinds of servers in SILC; normal servers and router servers.
434 This section focuses on the normal server and router server is described
435 in the section 3.3 Router.
437 Normal servers may not directly connect to other normal server. Normal
438 servers may only directly connect to router server. If the message sent
439 by the client is destined outside the local server it is always sent to
440 the router server for further routing. Server may only have one active
441 connection to router on same port. Normal server may not connect to other
442 cell's router except in situations where its cell's router is unavailable.
444 Servers and routers in the SILC network are considered to be trusted.
445 With out a doubt, servers that are set to work on ports above 1023 are
446 not considered to be trusted. Also, the service provider acts important
447 role in the server's trustworthy.
451 3.2.1 Server's Local ID List
453 Normal server keeps various information about the clients and their end
454 users connected to it. Every normal server must keep list of all locally
455 connected clients, Client ID's, nicknames, usernames and hostnames and
456 user's real name. Normal servers only keeps local information and it
457 does not keep any global information. Hence, normal servers knows only
458 about their locally connected clients. This makes servers efficient as
459 they don't have to worry about global clients. Server is also responsible
460 of creating the Client ID's for their clients.
462 Normal server also keeps information about locally created channels and
465 Hence, local list for normal server includes:
468 server list - Router connection
476 client list - All clients in server
486 channel list - All channels in server
489 o Client ID's on channel
490 o Client ID modes on channel
499 Servers are distinguished from other servers by unique 64 bit Server ID.
500 The Server ID is used in the SILC to route messages to correct servers.
501 Server ID's also provide information for Client ID's, see section 3.1.1
502 Client ID. Server ID is defined as follows.
505 64 bit Server ID based on IPv4 addresses:
507 32 bit IP address of the server
511 o IP address of the server - This is the real IP address of
514 o Port - This is the port the server is binded to.
516 o Random number - This is used to further unify the Server ID.
519 Collisions are not expected to happen in any conditions. The Server ID
520 is always created by the server itself and server is resposible of
521 distributing it to the router.
525 3.2.3 SILC Server Ports
527 SILC uses currently TCP port 334 on SILC network. However, this is not
528 official port assigned for SILC. Official port has been requested by
531 If there are needs to create new SILC networks in the future the port
532 numbers must be officially assigned by the IANA. Most convenience case
533 would be to assign port numbers upwards from 334.
535 Server on network above privileged ports (>1023) should not be trusted
536 as they could have been set up by untrusted party.
542 Router server in SILC network is responsible for keeping the cell together
543 and routing messages to other servers and to other routers. Router server
544 is also a normal server thus clients may connect to it as it would be
545 just normal SILC server.
547 However, router servers has a lot of important tasks that normal servers
548 do not have. Router server knows everything about everything in the SILC.
549 They know all clients currently on SILC, all servers and routers and all
550 channels in SILC. Routers are the only servers in SILC that care about
551 global information and keeping them up to date at all time. And, this
552 is what they must do.
556 3.3.1 Router's Local ID List
558 Router server as well must keep local list of connected clients and
559 locally created channels. However, this list is extended to include all
560 the informations of the entire cell, not just the server itself as for
563 However, on router this list is a lot smaller since routers do not keep
564 information about user's nickname, username and hostname and real name
565 since these are not needed by the router. Router keeps only information
568 Hence, local list for router includes:
571 server list - All servers in the cell
578 client list - All clients in the cell
581 channel list - All channels in the cell
583 o Client ID's on channel
584 o Client ID modes on channel
589 Note that locally connected clients and other information include all the
590 same information as defined in section section 3.2.1 Server's Local ID
595 3.3.2 Router's Global ID List
597 Router server must also keep global list. Normal servers do not have
598 global list as they know only about local information. Global list
599 includes all the clients on SILC, their Client ID's, all created channels
600 and their Channel ID's and all servers and routers on SILC and their
601 Server ID's. That is said, global list is for global information and the
602 list must not include the local information already on the router's local
605 Note that the global list does not include information like nicknames,
606 usernames and hostnames or user's real names. Router does not keep
607 these informations as they are not needed by the router. This
608 information is available from the client's server which maybe queried
611 Hence, global list includes:
614 server list - All servers in SILC
619 client list - All clients in SILC
622 channel list - All channels in SILC
624 o Client ID's on channel
625 o Client ID modes on channel
630 3.3.3 Router's Server ID
632 Router's Server ID's are equivalent to normal Server ID's. As routers
633 are normal servers as well same types of ID's applies for routers as well.
634 Thus, see section 3.2.2 Server ID. Server ID's for routers are always
635 created by the remote router where the router is connected to.
641 A channel is a named group of one or more clients which will all receive
642 messages addressed to that channel. The channel is created when first
643 client requests JOIN command to the channel, and the channel ceases to
644 exist when the last client leaves it. When channel exists, any client
645 can reference it using the name of the channel.
647 Channel names are unique although the real uniqueness comes from 64 bit
648 Channel ID that unifies each channel. However, channel names are still
649 unique and no two global channels with same name may exist. Channel name
650 is a string which begins with `#' character. There is no limit on the
651 length of the channel name. Channel names may not contain any spaces
652 (` '), any non-printable ASCII characters, commas (`,') and wildcard
655 Channels can have operators that can administrate the channel and
656 operate all of its modes. Following operators on channel exist on SILC
660 o Channel founder - When channel is created the joining client becomes
661 channel founder. Channel founder is channel operator with some more
662 privileges. Basically, channel founder can fully operate the channel
663 and all of its modes. The privileges are limited only to the particular
664 channel. There can be only one channel founder per channel. Channel
665 founder supersedes channel operator's privileges.
667 Channel founder privileges cannot be removed by any other operator on
668 channel. When channel founder leaves the channel there is no channel
669 founder on the channel. Channel founder also cannot be removed by
670 force from the channel.
672 o Channel operator - When client joins to channel that has not existed
673 previously it will become automatically channel operator (and channel
674 founder discussed above). Channel operator is able administrate the
675 channel, set some modes on channel, remove a badly behaving client from
676 the channel and promote other clients to become channel operator.
677 The privileges are limited only to the particular channel.
679 Normal channel user may be promoted (opped) to channel operator
680 gaining channel operator privileges. Channel founder or other channel
681 operator may also demote (deop) channel operator to normal channel
689 Channels are distinguished from other channels by unique Channel ID.
690 The Channel ID is a 64 bit ID and collisions are not expected to happen
691 in any conditions. Channel names are just for logical use of channels.
692 The Channel ID is created by the server where the channel is created.
693 The Channel ID is defined as follows.
696 64 bit Channel ID based on IPv4 addresses:
698 32 bit Router's Server ID IP address (bits 1-32)
699 16 bit Router's Server ID port (bits 33-48)
702 o Router's Server ID IP address - Indicates the IP address of
703 the router of the cell where this channel is created. This is
704 taken from the router's Server ID. This way SILC router knows
705 where this channel resides in the SILC network.
707 o Router's Server ID port - Indicates the port of the channel on
708 the server. This is taken from the router's Server ID.
710 o Random number - To further unify the Channel ID. This makes
711 sure that there are no collisions. This also means that
712 in a cell there can be 2^16 channels.
719 Operators are normal users with extra privileges to their server or
720 router. Usually these people are SILC server and router administrators
721 that take care of their own server and clients on them. The purpose of
722 operators is to administrate the SILC server or router. However, even
723 an operator with highest privileges is not able to enter invite-only
724 channel, to gain access to the contents of a encrypted and authenticated
725 packets traveling in the SILC network or to gain channel operator
726 privileges on public channels without being promoted. They have the
727 same privileges as everyone else except they are able to administrate
728 their server or router.
734 Commands are very important part on SILC network especially for client
735 which uses commands to operate on the SILC network. Commands are used
736 to set nickname, join to channel, change modes and many other things.
738 Client usually sends the commands and server replies by sending a reply
739 packet to the command. Server may also send commands usually to serve
740 the original client's request. However, server may not send command
741 to client and there are some commands that server must not send.
743 Note that the command reply is usually sent only after client has sent
744 the command request but server is allowed to send command reply packet
745 to client even if client has not requested the command. Client may,
746 however, choose not to accept the command reply, but there are some
747 command replies that the client should accept. Example of a such
748 command reply is reply to SILC_COMMAND_CMODE command that the server
749 uses to distribute the channel mode on all clients on the channel
750 when the mode has changed.
752 It is expected that some of the commands may be miss-used by clients
753 resulting various problems on the server side. Every implementation
754 should assure that commands may not be executed more than once, say,
755 in two (2) seconds. This should be sufficient to prevent the miss-use
758 SILC commands are described in section 5 SILC Commands.
764 Packets are naturally the most important part of the protocol and the
765 packets are what actually makes the protocol. Packets in SILC network
766 are always encrypted using, usually, the shared secret session key
767 or some other key, for example, channel key, when encrypting channel
768 messages. The SILC Packet Protocol is a wide protocol and is described
769 in [SILC2]. This document does not define or describe details of
774 3.8 Packet Encryption
776 All packets passed in SILC network must be encrypted. This section
777 defines how packets must be encrypted in the SILC network. The detailed
778 description of the actual encryption process of the packets are
779 described in [SILC2].
781 Client and its server shares secret symmetric session key which is
782 established by the SILC Key Exchange Protocol, described in [SILC3].
783 Every packet sent from client to server, with exception of packets for
784 channels, are encrypted with this session key.
786 Channels has their own key that are shared by every client on the channel.
787 However, the channel keys are cell specific thus one cell does not know
788 the channel key of the other cell, even if that key is for same channel.
789 Channel key is also known by the routers and all servers that has clients
790 on the channel. However, channels may have channel private keys that
791 are entirely local setting for client. All clients on the channel must
792 know the channel private key before hand to be able to talk on the
793 channel. In this case, no server or router knows the key for channel.
795 Server shares secret symmetric session key with router which is
796 established by the SILC Key Exchange Protocol. Every packet passed from
797 server to router, with exception of packets for channels, are encrypted
798 with the shared session key. Same way, router server shares secret
799 symmetric key with its primary route. However, every packet passed
800 from router to other router, including packets for channels, are
801 encrypted with the shared session key. Every router connection has
802 their own session keys.
806 3.8.1 Determination of the Source and the Destination
808 The source and the destination of the packet needs to be determined
809 to be able to route the packets to correct receiver. This information
810 is available in the SILC Packet Header which is included in all packets
811 sent in SILC network. The SILC Packet Header is described in [SILC2].
813 The header is always encrypted with the session key who is next receiver
814 of the packet along the route. The receiver of the packet, for example
815 a router along the route, is able to determine the sender and the
816 destination of the packet by decrypting the SILC Packet Header and
817 checking the ID's attached to the header. The ID's in the header will
818 tell to where the packet needs to be sent and where it is coming from.
820 The header in the packet does not change during the routing of the
821 packet. The original sender, for example client, assembles the packet
822 and the packet header and server or router between the sender and the
823 receiver must not change the packet header.
825 Note that the packet and the packet header may be encrypted with
826 different keys. For example, packets to channels are encrypted with
827 the channel key, however, the header is encrypted with the session key
828 as described above. However, the header and the packet may be encrypted
829 with same key. This is case, for example, with command packets.
833 3.8.2 Client To Client
835 Process of message delivery and encryption from client to another
836 client is as follows.
838 Example: Private message from client to another client on different
839 servers. Clients do not share private message delivery
840 keys; normal session keys are used.
842 o Client 1. sends encrypted packet to its server. The packet is
843 encrypted with the session key shared between client and its
846 o Server determines the destination of the packet and decrypts
847 the packet. Server encrypts the packet with session key shared
848 between the server and its router, and sends the packet to the
851 o Router determines the destination of the packet and decrypts
852 the packet. Router encrypts the packet with session key
853 shared between the router and the destination server, and sends
854 the packet to the server.
856 o Server determines the client to which the packet is destined
857 to and decrypts the packet. Server encrypts the packet with
858 session key shared between the server and the destination client,
859 and sends the packet to the client.
861 o Client 2. decrypts the packet.
864 Example: Private message from client to another client on different
865 servers. Clients has established secret shared private
866 message delivery key with each other and that is used in
867 the message encryption.
869 o Client 1. sends encrypted packet to its server. The packet is
870 encrypted with the private message delivery key shared between
873 o Server determines the destination of the packet and sends the
874 packet to the router.
876 o Router determines the destination of the packet and sends the
877 packet to the server.
879 o Server determines the client to which the packet is destined
880 to and sends the packet to the client.
882 o Client 2. decrypts the packet with the secret shared key.
885 If clients share secret key with each other the private message
886 delivery is much simpler since servers and routers between the
887 clients do not need to decrypt and re-encrypt the packet.
889 The process for clients on same server is much simpler as there are
890 no need to send the packet to the router. The process for clients
891 on different cells is same as above except that the packet is routed
892 outside the cell. The router of the destination cell routes the
893 packet to the destination same way as described above.
897 3.8.3 Client To Channel
899 Process of message delivery from client on channel to all the clients
902 Example: Channel of four users; two on same server, other two on
903 different cells. Client sends message to the channel.
905 o Client 1. encrypts the packet with channel key and sends the
906 packet to its server.
908 o Server determines local clients on the channel and sends the
909 packet to the Client on the same server. Server then sends
910 the packet to its router for further routing.
912 o Router determines local clients on the channel, if found
913 sends packet to the local clients. Router determines global
914 clients on the channel and sends the packet to its primary
915 router or fastest route.
917 o (Other router(s) do the same thing and sends the packet to
920 o Server determines local clients on the channel and sends the
921 packet to the client.
923 o All clients receiving the packet decrypts the packet.
927 3.8.4 Server To Server
929 Server to server packet delivery and encryption is described in above
930 examples. Router to router packet delivery is analogous to server to
931 server. However, some packets, such as channel packets, are processed
932 differently. These cases are described later in this document and
933 more in detail in [SILC2].
937 3.9 Key Exchange And Authentication
939 Key exchange is done always when for example client connects to server
940 but also when server and router and router and router connects to each
941 other. The purpose of key exchange protocol is to provide secure key
942 material to be used in the communication. The key material is used to
943 derive various security parameters used to secure SILC packets. The
944 SILC Key Exchange protocol is described in detail in [SILC3].
946 Authentication is done after key exchange protocol has been successfully
947 completed. The purpose of authentication is to authenticate for example
948 client connecting to the server. However, Usually clients are accepted
949 to connect to server without explicit authentication. Servers are
950 required use authentication protocol when connecting. The authentication
951 may be based on passphrase (pre-shared-secret) or public key. The
952 connection authentication protocol is described in detail in [SILC3].
958 This section defines all the allowed algorithms that can be used in
959 the SILC protocol. This includes mandatory cipher, mandatory public
960 key algorithm and MAC algorithms.
966 Cipher is the encryption algorithm that is used to protect the data
967 in the SILC packets. See [SILC2] of the actual encryption process and
968 definition of how it must be done. SILC has a mandatory algorithm that
969 must be supported in order to be compliant with this protocol.
971 Following ciphers are defined in SILC protocol:
974 blowfish-cbc Blowfish in CBC mode (mandatory)
975 twofish-cbc Twofish in CBC mode (optional)
976 rc6-cbc RC6 in CBC mode (optional)
977 rc5-cbc RC5 in CBC mode (optional)
978 mars-cbc Mars in CBC mode (optional)
979 none No encryption (optional)
983 All algorithms must use minimum of 128 bit key, by default. Several
984 algorithms, however, supports longer keys and it is recommended to use
985 longer keys if they are available.
987 Algorithm none does not perform any encryption process at all and
988 thus is not recommended to be used. It is recommended that no client
989 or server implementation would accept none algorithms except in special
992 Additional ciphers may be defined to be used in SILC by using the
993 same name format as above.
1001 3.10.2 Public Key Algorithms
1003 Public keys are used in SILC to authenticate entities in SILC network
1004 and to perform other tasks related to public key cryptography. The
1005 public keys are also used in the SILC Key Exchange protocol [SILC3].
1007 Following public key algorithms are defined in SILC protocol:
1014 Both of the algorithms are described in [Scheneir] and [Menezes].
1016 Additional public key algorithms may be defined to be used in SILC.
1020 3.10.3 MAC Algorithms
1022 Data integrity is protected by computing a message authentication code
1023 (MAC) of the packet data. See [SILC2] for details how to compute the
1026 Following MAC algorithms are defined in SILC protocol:
1029 hmac-sha1 HMAC-SHA1, length = 20 (mandatory)
1030 hmac-md5 HMAC-MD5, length = 16 (optional)
1031 none No MAC (optional)
1034 The none MAC is not recommended to be used as the packet is not
1035 authenticated when MAC is not computed. It is recommended that no
1036 client or server would accept none MAC except in special debugging
1039 The HMAC algorithm is described in [HMAC] and hash algorithms that
1040 are used as part of the HMACs are described in [Scheneir] and in
1043 Additional MAC algorithms may be defined to be used in SILC.
1047 3.10.4 Compression Algorithms
1049 SILC protocol supports compression that may be applied to unencrypted
1050 data. It is recommended to use compression on slow links as it may
1051 significantly speed up the data transmission. By default, SILC does not
1052 use compression which is the mode that must be supported by all SILC
1055 Following compression algorithms are defined:
1058 none No compression (mandatory)
1059 zlib GBU ZLIB (LZ77) compression (optional)
1062 Additional compression algorithms may be defined to be used in SILC.
1066 3.11 SILC Public Key
1068 This section defines the type and format of the SILC public key. All
1069 implementations must support this public key type. See [SILC3] for
1070 other optional public key and certificate types allowed in SILC
1071 protocol. Public keys in SILC may be used to authenticate entities
1072 and to perform other tasks related to public key cryptography.
1074 The format of the SILC Public Key is as follows:
1080 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
1081 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1082 | Public Key Length |
1083 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1084 | Algorithm Name Length | |
1085 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1089 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1090 | Identifier Length | |
1091 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1095 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1099 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1103 Figure 4: SILC Public Key
1107 o Public Key Length (4 bytes) - Indicates the full length
1108 of the public key, not including this field.
1110 o Algorithm Name Length (2 bytes) - Indicates the length
1111 of the Algorithm Length field, not including this field.
1113 o Algorithm name (variable length) - Indicates the name
1114 of the public key algorithm that the key is. See the
1115 section 3.10.2 Public Key Algorithms for defined names.
1117 o Identifier Length (2 bytes) - Indicates the length of
1118 the Identifier field, not including this field.
1120 o Identifier (variable length) - Indicates the identifier
1121 of the public key. This data can be used to identify
1122 the owner of the key. The identifier is of following
1126 HN Host name or IP address
1133 Examples of an identifier:
1135 `UN=priikone, HN=poseidon.pspt.fi, E=priikone@poseidon.pspt.fi'
1137 `UN=sam, HN=dummy.fi, RN=Sammy Sam, O=Company XYZ, C=Finland'
1139 At least user name (UN) and host name (HN) must be provided as
1140 identifier. The fields are separated by commas (`,'). If
1141 comma is in the identifier string it must be written as `\\,',
1142 for example, `O=Company XYZ\\, Inc.'.
1144 o Public Data (variable length) - Includes the actual
1145 public data of the public key.
1147 The format of this field for RSA algorithm is
1156 The format of this field for DSS algorithm is
1168 The variable length fields are multiple precession
1169 integers encoded as strings in both examples.
1171 Other algorithms must define their own type of this
1172 field if they are used.
1175 All fields in the public key are in MSB (most significant byte first)
1182 This section describes various SILC procedures such as how the
1183 connections are created and registered, how channels are created and
1184 so on. The section describes the procedures only generally as details
1185 are described in [SILC2] and [SILC3].
1189 4.1 Creating Client Connection
1191 This section descibres the procedure when client connects to SILC server.
1192 When client connects to server the server must perform IP address lookup
1193 and reverse IP address lookup to assure that the origin host really is
1194 who it claims to be. Client, host, connecting to server must have
1195 both valid IP address and fully qualified domain name (FQDN).
1197 After that client and server performs SILC Key Exchange protocol which
1198 will provide the key material used later in the communication. The
1199 key exchange protocol must be completed successfully before the connection
1200 registration may continue. The SILC Key Exchange protocol is described
1203 Typical server implementation would keep a list of connections that it
1204 allows to connect to the server. The implementation would check, for
1205 example, the connecting client's IP address from the connection list
1206 before the SILC Key Exchange protocol has been started. Reason for
1207 this is that if the host is not allowed to connect to the server there
1208 is no reason to perform a key exchange protocol.
1210 After successful key exchange protocol the client and server performs
1211 connection authentication protocol. The purpose of the protocol is to
1212 authenticate the client connecting to the server. Flexible
1213 implementation could also accept the client to connect to the server
1214 without explicit authentication. However, if authentication is
1215 desired for a specific client it may be based on passphrase or
1216 public key authentication. If authentication fails the connection
1217 must be terminated. The connection authentication protocol is described
1220 After successful key exchange and authentication protocol the client
1221 registers itself by sending SILC_PACKET_NEW_CLIENT packet to the
1222 server. This packet includes various information about the client
1223 that the server uses to create the client. Server creates the client
1224 and sends SILC_PACKET_NEW_ID to the client which includes the created
1225 Client ID that the client must start using after that. After that
1226 all SILC packets from the client must have the Client ID as the
1227 Source ID in the SILC Packet Header, described in [SILC2].
1229 Client must also get the server's Server ID that is to be used as
1230 Destination ID in the SILC Packet Header when communicating with
1231 the server (for example when sending commands to the server). The
1232 ID may be resolved in two ways. Client can take the ID from an
1233 previously received packet from server that must include the ID,
1234 or to send SILC_COMMAND_INFO command and receive the Server ID as
1237 Server may choose not to use the information received in the
1238 SILC_PACKET_NEW_CLIENT packet. For example, if public key or
1239 certificate were used in the authentication, server may use those
1240 informations rather than what it received from client. This is suitable
1241 way to get the true information about client if it is available.
1243 The nickname of client is initially set to the username sent in the
1244 SILC_PACKET_NEW_CLIENT packet. User should set the nickname to more
1245 suitable by sending SILC_COMMAND_NICK command. However, this is not
1246 required as part of registration process.
1248 Server must also distribute the information about newly registered
1249 client to its router (or if the server is router, to all routers in
1250 the SILC network). More information about this in [SILC2].
1254 4.2 Creating Server Connection
1256 This section descibres the procedure when server connects to its
1257 router (or when router connects to other router, the cases are
1258 equivalent). The procedure is very much alike when client connects
1259 to the server thus it is not repeated here.
1261 One difference is that server must perform connection authentication
1262 protocol with proper authentication. Proper authentication is based
1263 on passphrase or public key authentication.
1265 After server and router has successfully performed the key exchange
1266 and connection authentication protocol, the server register itself
1267 to the router by sending SILC_PACKET_NEW_SERVER packet. This packet
1268 includes the server's Server ID that it has created by itself and
1269 other relevant information about the server.
1271 After router has received the SILC_PACKET_NEW_SERVER packet it
1272 distributes the information about newly registered server to all routers
1273 in the SILC network. More information about this in [SILC2].
1275 As client needed to resolve the destination ID this must be done by the
1276 server that connected to the router, as well. The way to resolve it is
1277 to get the ID from previously received packet. Server must also start
1278 using its own Server ID as Source ID in SILC Packet Header and the
1279 router's Server ID as Destination when communicating with the router.
1281 If the server has already connected clients and locally created
1282 channels the server must distribute these informations to the router.
1283 The distribution is done by sending packet SILC_PACKET_NEW_CHANNEL.
1284 See [SILC2] for more information on this.
1288 4.3 Joining to a Channel
1290 This section describes the procedure when client joins to a channel.
1291 Client may join to channel by sending command SILC_COMMAND_JOIN to the
1292 server. If the receiver receiving join command is normal server the
1293 server must check its local list whether this channel already exists
1294 locally. This would indicate that some client connected to the server
1295 has already joined to the channel. If this is case the client is
1296 joined to the client, new channel key is created and information about
1297 newly joined channel is sent to the router. The new channel key is
1298 also distributed to the router and to all clients on the channel.
1300 If the channel does not exist in the local list the command must be
1301 sent to the router which will then perform the actual joining
1302 procedure. When server receives the reply to the command from the
1303 router it must be distributed to the client who sent the command
1304 originally. Server will also receive the channel key from the server
1305 that it must distribute to the client who originally requested the
1306 join command. The server must also save the channel key.
1308 If the receiver of the join command is router it must first check its
1309 local list whether anyone in the cell has already joined to the channel.
1310 If this is the case the client is joined to the channel and reply is
1311 sent to the client. If the command was sent by server the command reply
1312 is sent to the server who sent it. Then the router must also create
1313 new channel key and distribute it to all clients on the channel and
1314 all servers that has clients on the channel.
1316 If the channel does not exist on the router's local list it must
1317 check the global list whether the channel exists at all. If it does
1318 the client is joined to the channel as described previously. If
1319 the channel does not exist the channel is created and the client
1320 is joined to the channel. The channel key is also created and
1321 distributed as previously described. The client joining to the created
1322 channel is made automatically channel founder and both channel founder
1323 and channel operator privileges is set for the client.
1325 When the router joins the client to the channel it must send
1326 information about newly joined client to all routers in the SILC
1327 network. Also, if the channel was created in the process, information
1328 about newly created channel must also be distributed to all routers.
1329 The distribution of newly created channel is done by sending packet
1330 SILC_PACKET_NEW_CHANNEL.
1332 It is important to note that new channel key is created always when
1333 new client joins to channel, whether the channel has existed previously
1334 or not. This way the new client on the channel is not able to decrypt
1335 any of the old traffic on the channel.
1337 Client who receives the reply to the join command must start using
1338 the received Channel ID in the channel message communication thereafter.
1339 However, client must not start communicating on the channel before
1340 it has received the packet SILC_PACKET_CHANNEL_KEY.
1342 If client wants to know the other clients currently on the channel
1343 the client must send SILC_COMMAND_NAMES command to receive a list of
1344 channel users. Server implementation, however, may send command reply
1345 packet to SILC_COMMAND_NAMES command after client has joined to the
1346 channel even if the client has not sent the command.
1350 4.4 Channel Key Generation
1352 Channel keys are created by router who creates the channel by taking
1353 enough randomness from cryptographically strong random number generator.
1354 The key is generated always when channel is created, when new client
1355 joins a channel and after the key has expired. Key could expire for
1358 The key must also be re-generated whenever some client leaves a channel.
1359 In this case the key is created from scratch by taking enough randomness
1360 from the random number generator. After that the key is distributed to
1361 all clients on the channel. However, channel keys are cell specific thus
1362 the key is created only on the cell where the client, who leaved the
1363 channel, exists. While the server or router is creating the new channel
1364 key, no other client may join to the channel. Messages that are sent
1365 while creating the new key are still processed with the old key. After
1366 server has sent the SILC_PACKET_CHANNEL_KEY packet must client start
1367 using the new key. If server creates the new key the server must also
1368 send the new key to its router. See [SILC2] on more information about
1369 how channel messages must be encrypted and decrypted when router is
1374 4.5 Private Message Sending and Reception
1376 Private messages are sent point to point. Client explicitly destines
1377 a private message to specific client that is delivered to only to that
1378 client. No other client may receive the private message. The receiver
1379 of the private message is destined in the SILC Packet Header as any
1380 other packet as well.
1382 If the sender of a private message does not know the receiver's Client
1383 ID, it must resolve it from server. There are two ways to resolve the
1384 client ID from server; it is recommended that client ipmlementations
1385 send SILC_COMMAND_IDENTIFY command to receive the Client ID. Client
1386 may also send SILC_COMMAND_WHOIS command to receive the Client ID.
1387 If the sender has received earlier a private message from the receiver
1388 it should have cached the Client ID from the SILC Packet Header.
1390 Receiver of a private message should not explicitly trust the nickname
1391 that it receives in the Private Message Payload, described in [SILC2].
1392 Implementations could resolve the nickname from server, as described
1393 previously, and compare the received Client ID and the SILC Packet
1394 Header's Client ID. The nickname in the payload is merely provided
1395 to be displayed for end user.
1397 See [SILC2] for describtion of private message encryption and decryption
1402 4.6 Private Message Key Generation
1404 Private message may be protected by key generated by client. The key
1405 may be generated and sent to the other client by sending packet
1406 SILC_PACKET_PRIVATE_MESSAGE_KEY which travels through the network
1407 and is secured by session keys. After that the private message key
1408 is used in the private message communication between those clients.
1409 See more information about how this works technically in [SILC2].
1411 Other choice is to entirely use keys that are not sent through
1412 the SILC network at all. This significantly adds security. This key
1413 would be pre-shared-key that is known by both of the clients. Both
1414 agree about using the key and starts sending packets that indicate
1415 that the private message is secured using private message key. This
1416 is the technical aspect mentioned previously that is described
1419 If the private message keys are not set to be used, which is the
1420 case by default in SILC, the private messages are secured by using
1421 normal session keys established by SILC Key Exchange protocol.
1425 4.7 Channel Message Sending and Reception
1427 Channel messages are delivered to group of users. The group forms a
1428 channel and all clients on the channel receives messages sent to the
1431 Channel messages are destined to channel by specifying the Channel ID
1432 as Destination ID in the SILC Packet Header. The server must then
1433 distribute the message to all clients on the channel by sending the
1434 channel message destined explicitly to a client on the channel.
1436 See [SILC2] for describtion of channel message encryption and decryption
1441 4.8 Session Key Regeneration
1443 Session keys should be regenerated peridiocally, say, once in an hour.
1444 The re-key process is started by sending SILC_PACKET_REKEY packet to
1445 other end, to indicate that re-key must be performed.
1447 If perfect forward secrecy (PFS) flag was selected in the SILC Key
1448 Exchange protocol [SILC3] the re-key must cause new key exchange with
1449 SKE protocol. In this case the protocol is secured with the old key
1450 and the protocol results to new key material. See [SILC3] for more
1451 information. After the SILC_PACKET_REKEY packet is sent the sender
1452 will perform the SKE protocol.
1454 If PFS flag was not set, which is the default case, then re-key is done
1455 without executing SKE protocol. In this case, the new key is created by
1456 hashing the old key with hash function selected earlier in the SKE
1457 protocol. If the digest length of the hash function is too short for the
1458 key, then the key is distributed as described in section Processing the
1459 Key Material in [SILC3]. After both parties has regenerated the session
1460 key, both send SILC_PACKET_REKEY_DONE packet to each other. These packets
1461 are still secured with the old key. After these packets, following
1462 packets must be protected with the new key.
1466 4.9 Command Sending and Reception
1468 Client usually sends the commands in the SILC network. In this case
1469 the client simply sends the command packet to server and the server
1470 processes it and replies with command reply packet.
1472 However, if the server is not able to process the command, it is usually
1473 sent to the server's router. This is case for example with commands such
1474 as, SILC_COMMAND_JOIN and SILC_COMMAND_WHOIS commands. However, there
1475 are other commands as well. For example, if client sends the WHOIS
1476 command requesting specific information about some client the server must
1477 send the WHOIS command to router so that all clients in SILC network
1478 are searched. The router, on the other hand, sends the WHOIS command
1479 to further to receive the exact information about the requested client.
1480 The WHOIS command travels all the way to the server who owns the client
1481 and it replies with command reply packet. Finally, the server who
1482 sent the command receives the command reply and it must be able to
1483 determine which client sent the original command. The server then
1484 sends command reply to the client. Implementations should have some
1485 kind of cache to handle, for example, WHOIS information. Servers
1486 and routers along the route could all cache the information for faster
1487 referencing in the future.
1489 The commands sent by server may be sent hop by hop until someone is able
1490 to process the command. However, it is preferred to destine the command
1491 as precisely as it is possible. In this case, other routers en route
1492 must route the command packet by checking the true sender and true
1493 destination of the packet. However, servers and routers must not route
1494 command reply packets to clients coming from other server. Client
1495 must not accept command reply packet originated from anyone else but
1496 from its own server.
1503 5.1 SILC Commands Syntax
1505 This section briefly describes the syntax of the command notions
1506 in this document. Every field in command is separated from each
1507 other by whitespaces (` ') indicating that each field is independent
1508 argument and each argument must have own Command Argument Payload.
1509 The number of maximum arguments are defined with each command
1510 separately. The Command Argument Payload is described in [SILC2].
1512 Every command defines specific number for each argument. Currently,
1513 they are defined in ascending order; first argument has number one
1514 (1), second has number two (2) and so on. This number is set into the
1515 Argument Type field in the Command Argument Payload. This makes it
1516 possible to send the arguments in free order as the number must be
1517 used to identify the type of the argument. This makes is it also
1518 possible to have multiple optional arguments in commands and in
1519 command replies. The number of argument is marked in parentheses
1520 before the actual argument.
1523 Example: Arguments: (1) <nickname> (2) <username@host>
1527 Every command replies with Status Payload. This payload tells the
1528 sender of the command whether the command was completed succefully or
1529 whether there was an error. If error occured the payload includes the
1530 error type. In the next section the Status Payload is not described
1531 as it is common to all commands and has been described here. Commands
1532 may reply with other arguments as well. These arguments are command
1533 specific and are described in the next section.
1542 Arguments: (1) <nickname>[@<server>] (2) <message>
1545 The command has maximum of 3 arguments. However, only first
1546 and second arguments are mandatory.
1548 First argument <nickname> is mandatory but may have optional
1549 <nickname@server> format as well. Second argument is mandatory
1550 <message> argument. Third argument is optional <count> argument.
1552 The numbers in parentheses are the argument specific numbers
1553 that specify the type of the argument in Command Argument Payload.
1554 The receiver always knows that, say, argument number two (2) is
1555 <message> argument, regardles of the ordering of the arguments in
1556 the Command Payload.
1558 Reply messages to the command:
1561 Arguments: (1) <Status Payload> (2) [<channel list>]
1562 (3) <idle time> (4) [<away message>]
1564 This command may reply with maximum of 4 arguments. However,
1565 only the first and third arguments are mandatory. The numbers
1566 in the parentheses have the same meaning as in the upper
1567 command sending specification.
1569 Every command reply with <Status Payload>, it is mandatory
1570 argument for all command replies and for this reason it is not
1571 described in the command reply descriptions.
1576 SILC_STATUS_ERR_TOO_MANY_TARGETS
1577 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1578 SILC_STATUS_ERR_NO_SUCH_NICK
1580 Every command reply also defines set of status message that it
1581 may return inside the <Status Payload>. All status messages
1582 are defined in the section 5.3 SILC Command Status Types.
1587 5.2 SILC Commands List
1589 This section lists all SILC commands, however, it is expected that a
1590 implementation and especially client implementation has many more
1591 commands that has only local affect. These commands are official
1592 SILC commands that has both client and server sides and cannot be
1593 characterized as local commands.
1595 List of all defined commands in SILC follows.
1600 None. This is reserved command and must not be sent.
1603 2 SILC_COMMAND_WHOIS
1606 Arguments: (1) <nickname>[@<server>] (2) [<count>]
1608 Whois. Whois command is used to query various information about
1609 specific user. The user maybe requested by their nickname and
1610 server name. The query may find multiple matching users as
1611 there are no unique nicknames in the SILC. The <count> option
1612 maybe given to narrow down the number of accepted results. If
1613 this is not defined there are no limit of accepted results.
1614 The query may also be narrowed down by defining the server name
1617 To prevent miss-use of this service wildcards in the nickname
1618 or in the servername are not permitted. It is not allowed
1619 to request all users on some server. The WHOIS requests must
1620 be based on specific nickname request.
1622 The WHOIS request must be always forwarded to router by server
1623 so that all users are searched. However, the server still must
1624 search its locally connected clients. The server must send
1625 this command to the server who owns the requested client. That
1626 server must reply to the command.
1628 Reply messages to the command:
1631 Arguments: (1) <Status Payload> (2) <Client ID>
1632 (3) <nickname>[@<server>] (4) <username@host>
1633 (5) <real name> (6) [<channel list>]
1636 This command may reply with several command reply messages to
1637 form a list of results. In this case the status payload will
1638 include STATUS_LIST_START status in the first reply and
1639 STATUS_LIST_END in the last reply to indicate the end of the
1640 list. If there are only one reply the status is set to normal
1643 The command replies include the Client ID of the nickname,
1644 nickname and servername, username and hostnamea and users real
1645 name. Client should process these replies only after the last
1646 reply has been received with the STATUS_LIST_END status. If the
1647 <count> option were defined in the query there will be only
1648 <count> many replies from the server.
1653 SILC_STATUS_LIST_START
1654 SILC_STATUS_LIST_END
1655 SILC_STATUS_ERR_NO_SUCH_NICK
1656 SILC_STATUS_ERR_WILDCARDS
1657 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1658 SILC_STATUS_ERR_TOO_MANY_PARAMS
1661 3 SILC_COMMAND_WHOWAS
1664 Arguments: (1) <nickname>[@<server>] (2) [<count>]
1666 Whowas. This command is used to query history information about
1667 specific user. The user maybe requested by their nickname and
1668 server name. The query may find multiple matching users as there
1669 are no unique nicknames in the SILC. The <count> option maybe
1670 given to narrow down the number of accepted results. If this
1671 is not defined there are no limit of accepted results. The query
1672 may also be narrowed down by defining the server name of the
1675 To prevent miss-use of this service wildcards in the nickname
1676 or in the servername are not permitted. The WHOWAS requests must
1677 be based on specific nickname request.
1679 The WHOWAS request must be always forwarded to router by server
1680 so that all users are searched. However, the server still must
1681 search its locally connected clients.
1683 Reply messages to the command:
1686 Arguments: (1) <Status Payload> (2) <nickname>[@<server>]
1689 This command may reply with several command reply messages to form
1690 a list of results. In this case the status payload will include
1691 STATUS_LIST_START status in the first reply and STATUS_LIST_END in
1692 the last reply to indicate the end of the list. If there are only
1693 one reply the status is set to normal STATUS_OK.
1695 The command replies with nickname and username and hostname.
1696 Every server must keep history for some period of time of its
1697 locally connected clients.
1702 SILC_STATUS_LIST_START
1703 SILC_STATUS_LIST_END
1704 SILC_STATUS_ERR_NO_SUCH_NICK
1705 SILC_STATUS_ERR_WILDCARDS
1706 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1707 SILC_STATUS_ERR_TOO_MANY_PARAMS
1710 4 SILC_COMMAND_IDENTIFY
1713 Arguments: (1) <nickname>[@<server>] (2) [<count>]
1715 Identify. Identify command is almost analogous to WHOIS command,
1716 except that it does not return as much information. Only relevant
1717 information such as Client ID is returned. This is usually used
1718 to get the Client ID of a client used in the communication with
1721 The query may find multiple matching users as there are no unique
1722 nicknames in the SILC. The <count> option maybe given to narrow
1723 down the number of accepted results. If this is not defined there
1724 are no limit of accepted results. The query may also be narrowed
1725 down by defining the server name of the nickname.
1727 To prevent miss-use of this service wildcards in the nickname
1728 or in the servername are not permitted. It is not allowed
1729 to request all users on some server. The IDENTIFY requests must
1730 be based on specific nickname request.
1732 Implementations may not want to give interface access to this
1733 commands as it is hardly a command that would be used a end user.
1734 However, it must be implemented as it is used with private message
1737 The IDENTIFY must be always forwarded to router by server so that
1738 all users are searched. However, server must still search its
1739 locally connected clients.
1741 Reply messages to the command:
1744 Arguments: (1) <Status Payload> (2) <Client ID>
1745 (3) [<nickname>[@<server>]] (4) [<username@host>]
1747 This command may reply with several command reply messages to form
1748 a list of results. In this case the status payload will include
1749 STATUS_LIST_START status in the first reply and STATUS_LIST_END in
1750 the last reply to indicate the end of the list. If there are only
1751 one reply the status is set to normal STATUS_OK.
1753 The command replies with Client ID of the nickname and if more
1754 information is available it may reply with nickname and username
1755 and hostname. If the <count> option were defined in the query
1756 there will be only <count> many replies from the server.
1761 SILC_STATUS_LIST_START
1762 SILC_STATUS_LIST_END
1763 SILC_STATUS_ERR_NO_SUCH_NICK
1764 SILC_STATUS_ERR_WILDCARDS
1765 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1766 SILC_STATUS_ERR_TOO_MANY_PARAMS
1772 Arguments: (1) <nickname>
1774 Set/change nickname. This command is used to set nickname for
1775 user. There is no limit of the length of the nickname in SILC.
1776 Nickname must not include any spaces (` '), non-printable
1777 characters, commas (`,') and any wildcard characters. Note:
1778 nicknames in SILC are case-sensitive which must be taken into
1779 account when searching clients by nickname.
1781 Reply messages to the command:
1784 Arguments: (1) <Status Payload> (2) <New ID Payload>
1786 This command is replied always with New ID Payload that is
1787 generated by the server every time user changes their nickname.
1788 Client receiving this payload must start using the received
1789 Client ID as its current valid Client ID. The New ID Payload
1790 is described in [SILC2].
1795 SILC_STATUS_ERR_WILDCARDS
1796 SILC_STATUS_ERR_NICKNAME_IN_USE
1797 SILC_STATUS_ERR_BAD_NICKNAME
1798 SILC_STATUS_ERR_NOT_REGISTERED
1799 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1800 SILC_STATUS_ERR_TOO_MANY_PARAMS
1806 Arguments: (1) [<Channel ID>] [<server>]
1808 The list command is used to list channels and their topics on
1809 current server. If the <Channel ID> parameter is used, only the
1810 status of that channel is displayed. Secret channels are not
1811 listed at all. Private channels are listed with status indicating
1812 that the channel is private.
1814 If the <server> argument is specified the specified server's
1815 channels are listed. In this case the command must be sent to
1816 the server who owns the channel that was requested.
1818 Reply messages to the command:
1821 Arguments: (1) <Status Payload> (2) <channel>
1824 This command may reply with several command reply messages to form
1825 a list of results. In this case the status payload will include
1826 STATUS_LIST_START status in the first reply and STATUS_LIST_END in
1827 the last reply to indicate the end of the list. If there are only
1828 one reply the status is set to normal STATUS_OK.
1830 This command replies with channel name and the topic of the
1831 channel. If the channel is private channel the <topic> includes
1837 SILC_STATUS_LIST_START
1838 SILC_STATUS_LIST_END
1839 SILC_STATUS_ERR_WILDCARDS
1840 SILC_STATUS_ERR_NOT_REGISTERED
1841 SILC_STATUS_ERR_TOO_MANY_PARAMS
1842 SILC_STATUS_ERR_NO_SUCH_CHANNEL
1843 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
1844 SILC_STATUS_ERR_NO_SUCH_SERVER
1847 7 SILC_COMMAND_TOPIC
1850 Arguments: (1) <Channel ID> (2) [<server>]]
1852 This command is used to change or view the topic of a channel.
1853 The topic for channel <Channel ID> is returned if there is no
1854 <topic> given. If the <topic> parameter is present, the topic
1855 for that channel will be changed, if the channel modes permit
1858 Reply messages to the command:
1861 Arguments: (1) <Status Payload> (2) [<topic>]
1863 The command may reply with the topic of the channel if it is
1869 SILC_STATUS_ERR_NOT_ON_CHANNEL
1870 SILC_STATUS_ERR_WILDCARDS
1871 SILC_STATUS_ERR_NOT_REGISTERED
1872 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1873 SILC_STATUS_ERR_NO_SUCH_CHANNEL
1874 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
1875 SILC_STATUS_ERR_NO_CHANNEL_ID
1876 SILC_STATUS_ERR_BAD_CHANNEL_ID
1877 SILC_STATUS_ERR_TOO_MANY_PARAMS
1878 SILC_STATUS_ERR_NO_CHANNEL_PRIV
1881 8 SILC_COMMAND_INVITE
1884 Arguments: (1) <Client ID> (2) <channel>
1886 This command is used to invite other clients to join to the
1887 channel. There is no requirement that the channel the target
1888 client is being invited to must exist or be a valid channel.
1889 The <Client ID> argument is the target client's ID that is being
1892 Reply messages to the command:
1895 Arguments: (1) <Status Payload>
1897 This command replies only with Status Payload.
1902 SILC_STATUS_ERR_NOT_ON_CHANNEL
1903 SILC_STATUS_ERR_WILDCARDS
1904 SILC_STATUS_ERR_NOT_REGISTERED
1905 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1906 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
1907 SILC_STATUS_ERR_TOO_MANY_PARAMS
1908 SILC_STATUS_ERR_NO_RECIPIENT
1909 SILC_STATUS_ERR_USER_ON_CHANNEL
1910 SILC_STATUS_ERR_NO_CLIENT_ID
1916 Arguments: (1) [<quit message>]
1918 This command is used by client to end SILC session. The server
1919 must close the connection to a client which sends this command.
1920 if <quit message> is given it will be sent to other clients on
1921 channel if the client is on channel when quitting.
1923 Reply messages to the command:
1925 This command does not reply anything.
1928 10 SILC_COMMAND_KILL
1931 Arguments: (1) <Client ID> (2) [<comment>]
1933 This command is used by SILC operators to remove a client from
1934 SILC network. The removing has temporary effects and client may
1935 reconnect to SILC network. The <Client ID> is the client to be
1936 removed from SILC. The <comment> argument may be provided to
1937 give to the removed client some information why it was removed
1940 Reply messages to the command:
1943 Arguments: (1) <Status Payload>
1945 This command replies only with Status Payload.
1950 SILC_STATUS_ERR_WILDCARDS
1951 SILC_STATUS_ERR_NOT_REGISTERED
1952 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1953 SILC_STATUS_ERR_TOO_MANY_PARAMS
1954 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
1955 SILC_STATUS_ERR_NO_CLIENT_ID
1958 11 SILC_COMMAND_INFO
1961 Arguments: (1) [<server>]
1963 This command is used to fetch various information about a server.
1964 If <server> argument is specified the command must be sent to
1965 the requested server.
1967 Reply messages to the command:
1970 Arguments: (1) <Status Payload> (2) <Server ID>
1973 This command replies with the Server ID of the server and a
1974 string which tells the information about the server.
1979 SILC_STATUS_ERR_WILDCARDS
1980 SILC_STATUS_ERR_NOT_REGISTERED
1981 SILC_STATUS_ERR_TOO_MANY_PARAMS
1982 SILC_STATUS_ERR_NO_SUCH_SERVER_ID
1983 SILC_STATUS_ERR_NO_SUCH_SERVER
1988 12 SILC_COMMAND_CONNECT
1991 Arguments: (1) <Server ID>
1992 (2) [<remote server/router>[:<port>]]
1994 This command is used by operators to force a server to try to
1995 establish a new connection to another router (if the connecting
1996 server is normal server) or server (if the conneceting server is
1997 router server). Operator may specify the server/router to be
1998 connected by setting <remote server> argument.
2000 Reply messages to the command:
2003 Arguments: (1) <Status Payload>
2005 This command replies only with Status Payload.
2010 SILC_STATUS_ERR_WILDCARDS
2011 SILC_STATUS_ERR_NOT_REGISTERED
2012 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2013 SILC_STATUS_ERR_TOO_MANY_PARAMS
2014 SILC_STATUS_ERR_NO_SUCH_SERVER_ID
2015 SILC_STATUS_ERR_NO_SERVER_PRIV
2016 SILC_STATUS_ERR_NO_ROUTER_PRIV
2019 13 SILC_COMMAND_PING
2022 Arguments: (1) <Server ID>
2024 This command is used by clients to test the communication
2025 channel to its server if client suspects that the communication
2026 is not working correctly. The <Server ID> is the ID of the
2027 server the client is connected to.
2029 Reply messages to the command:
2032 Arguments: (1) <Status Payload>
2034 This command replies only with Status Payload. Server returns
2035 SILC_STATUS_OK in Status Payload if pinging was successful.
2040 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2041 SILC_STATUS_ERR_TOO_MANY_PARAMS
2042 SILC_STATUS_ERR_NO_SUCH_SERVER_ID
2043 SILC_STATUS_ERR_NOT_REGISTERED
2046 14 SILC_COMMAND_OPER
2049 Arguments: (1) <username> (2) <authentication data>
2051 This command is used by normal client to obtain server operator
2052 privileges on some server or router. Note that router operator
2053 has router privileges that supersedes the server operator
2054 privileges and this does not obtain those privileges. Client
2055 must use SILCOPER command to obtain router level privileges.
2057 The <username> is the username set in the server configurations
2058 as operator. The <authentication data> is the data that the
2059 client is authenticated against. It may be passphrase prompted
2060 for user on client's screen or it may be public key
2061 authentication data (data signed with private key), or
2064 Reply messages to the command:
2067 Arguments: (1) <Status Payload>
2069 This command replies only with Status Payload.
2074 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2075 SILC_STATUS_ERR_TOO_MANY_PARAMS
2076 SILC_STATUS_ERR_NOT_REGISTERED
2077 SILC_STATUS_ERR_BAD_PASSWORD
2078 SILC_STATUS_ERR_AUTH_FAILED
2081 15 SILC_COMMAND_JOIN
2084 Arguments: (1) <channel> (2) [<passphrase>]
2087 Join to channel/create new channel. This command is used to
2088 join to a channel. If the channel does not exist the channel is
2089 created on the server receiving the join request. The channel
2090 may be protected with passphrase. If this is the case the
2091 passphrase must be sent along the join command.
2093 The name of the <channel> must not include any spaces (` '),
2094 non-printable characters, commas (`,') or any wildcard characters.
2096 Cipher to be used to secure the traffic on the channel may be
2097 requested by sending the name of the requested <cipher>. This
2098 is used only if the channel does not exist and is created. If
2099 the channel already exists the cipher set previously for the
2100 channel will be used to secure the traffic.
2102 The server must check whether the user is allowed to join to
2103 the requested channel. Various modes set to the channel affect
2104 the ability of the user to join the channel. These conditions
2107 o The user must be invited to the channel if the channel
2108 is invite-only channel.
2110 o The Client ID/nickname/username/hostname must not match
2113 o The correct passphrase must be provided if passphrase
2114 is set to the channel.
2116 o The user count limit, if set, must not be reached.
2118 Reply messages to the command:
2121 Arguments: (1) <Status Payload> (2) <channel>
2122 (3) <Channel ID> (4) <channel mode mask>
2125 This command replies with the channel name requested by the
2126 client, channel ID of the channel and topic of the channel
2127 if it exists. It also replies with the channel mode mask
2128 which tells all the modes set on the channel. If the
2129 channel is created the mode mask is zero (0).
2131 Client must not start transmitting to the channel even after
2132 server has replied to this command. Client is permitted to
2133 start transmitting on channel after server has sent packet
2134 SILC_PACKET_CHANNEL_KEY to the client.
2139 SILC_STATUS_ERR_WILDCARDS
2140 SILC_STATUS_ERR_NOT_REGISTERED
2141 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2142 SILC_STATUS_ERR_TOO_MANY_PARAMS
2143 SILC_STATUS_ERR_BAD_PASSWORD
2144 SILC_STATUS_ERR_CHANNEL_IS_FULL
2145 SILC_STATUS_ERR_NOT_INVITED
2146 SILC_STATUS_ERR_BANNED_FROM_CHANNEL
2147 SILC_STATUS_ERR_BAD_CHANNEL
2148 SILC_STATUS_ERR_USER_ON_CHANNEL
2151 16 SILC_COMMAND_MOTD
2154 Arguments: (1) <server>
2156 This command is used to query the Message of the Day of a server.
2158 Reply messages to the command:
2161 Arguments: (1) <Status Payload> (2) [<motd>]
2163 This command replies with the motd message if it exists.
2168 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2169 SILC_STATUS_ERR_TOO_MANY_PARAMS
2170 SILC_STATUS_ERR_NOT_REGISTERED
2171 SILC_STATUS_ERR_NO_SUCH_SERVER
2174 17 SILC_COMMAND_UMODE
2177 Arguments: (1) <Client ID> (2) <client mode mask>
2179 This command is used by client to set/unset modes for itself.
2180 However, there are some modes that the client may not set itself,
2181 but they will be set by server. However, client may unset any
2182 mode. Modes may be masked together ORing them thus having
2183 several modes set. Client must keep its client mode mask
2184 locally so that the mode setting/unsetting would work without
2185 problems. Client may change only its own modes.
2187 Following client modes are defined:
2189 0x0000 SILC_UMODE_NONE
2191 No specific mode for client. This is the initial
2192 setting when new client is created. The client is
2196 0x0001 SILC_UMODE_SERVER_OPERATOR
2198 Marks the user as server operator. Client cannot
2199 set this mode itself. Server sets this mode to the
2200 client when client attains the server operator
2201 privileges by SILC_COMMAND_OPER command. Client
2202 may unset the mode itself.
2205 0x0002 SILC_UMODE_ROUTER_OPERATOR
2207 Marks the user as router (SILC) operator. Client
2208 cannot this mode itself. Router sets this mode to
2209 the client when client attains the router operator
2210 privileges by SILC_COMMAND_SILCOPER command. Client
2211 may unset the mode itself.
2213 Reply messages to the command:
2216 Arguments: (1) <Status Payload> (2) <client mode mask>
2218 This command replies with the changed client mode mask that
2219 the client is required to keep locally.
2224 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2225 SILC_STATUS_ERR_TOO_MANY_PARAMS
2226 SILC_STATUS_ERR_NOT_REGISTERED
2227 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2228 SILC_STATUS_ERR_BAD_CLIENT_ID
2229 SILC_STATUS_ERR_NOT_YOU
2230 SILC_STATUS_ERR_UNKNOWN_MODE
2231 SILC_STATUS_ERR_NO_RECIPIENT
2232 SILC_STATUS_ERR_NO_CLIENT_ID
2235 18 SILC_COMMAND_CMODE
2238 Arguments: (1) <Channel ID> (2) <channel mode mask>
2239 (3) [<user limit>] (4) [<passphrase>]
2240 (5) [<Client ID>] (6) [<cipher>[:<key len>]]
2242 This command is used by client to set or change channel flags on
2243 a channel. Channel has several modes that set various properties
2244 of a channel. Modes may be masked together by ORing them thus
2245 having several modes set. The <Channel ID> is the ID of the
2246 target channel. The client changing channel mode must be on
2247 the same channel and poses sufficient privileges to be able to
2250 Following channel modes are defined:
2252 0x0000 SILC_CMODE_NONE
2254 No specific mode on channel. This is the default when
2255 channel is created. This means that channel is just plain
2259 0x0001 SILC_CMODE_PRIVATE
2261 Channel is private channel. Private channels are shown
2262 in the channel list listed with SILC_COMMAND_LIST command
2263 with indicatioin that the channel is private. Also,
2264 client on private channel will no be detected to be on
2265 the channel as the channel is not shown in the client's
2266 currently joined channel list. Channel founder and
2267 channel operator may set/unset this mode.
2269 Typical implementation would use [+|-]p on user interface
2270 to set/unset this mode.
2273 0x0002 SILC_CMODE_SECRET
2275 Channel is secret channel. Secret channels are not shown
2276 in the list listed with SILC_COMMAND_LIST command. Secret
2277 channels can be considered to be invisible channels.
2278 Channel founder and channel operator may set/unset this
2281 Typical implementation would use [+|-]s on user interface
2282 to set/unset this mode.
2285 0x0004 SILC_CMODE_PRIVKEY
2287 Channel uses private channel key to protect the traffic
2288 on the channel. When this mode is set the client will be
2289 responsible to set the key it wants to use to encrypt and
2290 decrypt the traffic on channel. Server generated channel
2291 keys are not used at all. This mode provides additional
2292 security as clients on channel may agree to use private
2293 channel key that even servers do not know. Naturally,
2294 this requires that every client on the channel knows
2295 the key before hand (it is considered to be pre-shared-
2296 key). This specification does not define how the private
2297 channel key is set as it is entirely local setting on
2300 As it is local setting it is possible to have several
2301 private channel keys on one channel. In this case several
2302 clients can talk on same channel but only those clients
2303 that share the key with the message sender will be able
2304 to hear the talking. Client should not display those
2305 message for the end user that it is not able to decrypt
2306 when this mode is set.
2308 Only channel founder may set/unset this mode. If this
2309 mode is unset the server will distribute new channel
2310 key to all clients on the channel which will be used
2313 Typical implementation would use [+|-]k on user interface
2314 to set/unset this mode.
2317 0x0008 SILC_CMODE_INVITE
2319 Channel is invite only channel. Client may join to this
2320 channel only if it is invited to the channel. Channel
2321 founder and channel operator may set/unset this mode.
2323 Typical implementation would use [+|-]i on user interface
2324 to set/unset this mode.
2327 0x0010 SILC_CMODE_TOPIC
2329 The topic of the channel may only be set by client that
2330 is channel founder or channel operator. Normal clients
2331 on channel will not be able to set topic when this mode
2332 is set. Channel founder and channel operator may set/
2335 Typical implementation would use [+|-]t on user interface
2336 to set/unset this mode.
2339 0x0020 SILC_CMODE_ULIMIT
2341 User limit has been set to the channel. New clients
2342 may not join to the channel when the limit set is
2343 reached. Channel founder and channel operator may set/
2344 unset the limit. The <user limit> argument is the
2345 number of limited users.
2347 Typical implementation would use [+|-]l on user interface
2348 to set/unset this mode.
2351 0x0040 SILC_CMODE_PASSPHRASE
2353 Passphrase has been set to the channel. Client may
2354 join to the channel only if it is able to provide the
2355 correct passphrase. Setting passphrases to channel
2356 is entirely safe as all commands are protected in the
2357 SILC network. Only channel founder may set/unset
2358 the passphrase. The <passphrase> argument is the
2361 Typical implementation would use [+|-]a on user interface
2362 to set/unset this mode.
2365 0x0080 SILC_CMODE_BAN
2367 Ban mask has been set to the channel. The ban mask
2368 may be used to ban specific clients to join the channel.
2369 The <ban mask> argument is the set ban mask. When
2370 unsetting a ban mask the mask must be provided as
2371 argument. Channel founder and channel operator may
2372 set/unset this mode. Channel founder may not be
2373 added to the ban list.
2375 Typical implementation would use [+|-]b on user interface
2376 to set/unset this mode.
2379 0x0100 SILC_CMODE_OPERATOR
2381 Sets channel operator privileges on the channel for a
2382 client on the channel. The <Client ID> argument is the
2383 target client on the channel. Channel founder and
2384 channel operator may set/unset (promote/demote) this
2387 Typical implementation would use [+|-]o on user interface
2388 to set/unset this mode.
2391 0x0200 SILC_CMODE_CIPHER
2393 Sets specific cipher to be used to protect channel
2394 traffic. The <cipher> argument is the requested cipher.
2395 When set or unset the server must re-generate new
2396 channel key. If <key len> argument is specified with
2397 <cipher> argument the new key is generated of <key len>
2400 Typical implementation would use [+|-]c on user interface
2401 to set/unset this mode.
2404 To make the mode system work, client must keep the channel mode
2405 mask locally so that the mode setting and unsetting would work
2406 without problems. The client receives the initial channel mode
2407 mask when it joins to the channel. When the mode changes on
2408 channel the server distributes the changed channel mode mask to
2409 all clients on the channel by sending SILC_COMMAND_CMODE command
2412 Reply messages to the command:
2415 Arguments: (1) <Status Payload> (2) <channel mode mask>
2417 This command replies with the changed channel mode mask that
2418 client is required to keep locally. The same mask is also
2419 sent to all clients on channel by sending additional command
2425 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2426 SILC_STATUS_ERR_TOO_MANY_PARAMS
2427 SILC_STATUS_ERR_NOT_REGISTERED
2428 SILC_STATUS_ERR_NOT_ON_CHANNEL
2429 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2430 SILC_STATUS_ERR_BAD_CHANNEL_ID
2431 SILC_STATUS_ERR_NO_CHANNEL_ID
2432 SILC_STATUS_ERR_NO_CHANNEL_PRIV
2433 SILC_STATUS_ERR_UNKNOWN_MODE
2434 SILC_STATUS_ERR_NO_CLIENT_ID
2437 19 SILC_COMMAND_KICK
2440 Arguments: (1) <channel> (2) <Client ID>
2443 This command is used by channel operators to remove a client from
2444 channel. The <channel> argument is the channel the client to be
2445 removed is on currently. Note that the "kicker" must be on the same
2446 channel. If <comment> is provided it will be sent to the removed
2449 Reply messages to the command:
2452 Arguments: (1) <Status Payload>
2454 This command replies only with Status Payload.
2459 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2460 SILC_STATUS_ERR_TOO_MANY_PARAMS
2461 SILC_STATUS_ERR_NOT_REGISTERED
2462 SILC_STATUS_ERR_NO_SUCH_CHANNEL
2463 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2464 SILC_STATUS_ERR_NO_CHANNEL_PRIV
2465 SILC_STATUS_ERR_NO_CLIENT_ID
2468 20 SILC_COMMAND_RESTART
2473 This command may only be used by server operator to force a
2474 server to restart itself.
2476 Reply messages to the command:
2479 Arguments: (1) <Status Payload>
2481 This command replies only with Status Payload.
2486 SILC_STATUS_ERR_NOT_REGISTERED
2487 SILC_STATUS_ERR_NO_SERVER_PRIV
2490 21 SILC_COMMAND_CLOSE
2493 Arguments: (1) <Server ID>
2495 This command is used only by operator to close connection to a
2496 remote site. The <Server ID> argument is the ID of the remote
2497 site and must be valid.
2499 Reply messages to the command:
2502 Arguments: (1) <Status Payload>
2504 This command replies only with Status Payload.
2509 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2510 SILC_STATUS_ERR_TOO_MANY_PARAMS
2511 SILC_STATUS_ERR_NOT_REGISTERED
2512 SILC_STATUS_ERR_NO_SUCH_SERVER
2513 SILC_STATUS_ERR_NO_SERVER_PRIV
2514 SILC_STATUS_ERR_NO_SUCH_SERVER_ID
2522 This command is used only by operator to shutdown the server.
2523 All connections to the server will be closed and the server is
2526 Reply messages to the command:
2529 Arguments: (1) <Status Payload>
2531 This command replies only with Status Payload.
2536 SILC_STATUS_ERR_NOT_REGISTERED
2537 SILC_STATUS_ERR_NO_SERVER_PRIV
2540 23 SILC_COMMAND_SILCOPER
2543 Arguments: (1) <username> (2) <authentication data>
2545 This command is used by normal client to obtain router operator
2546 privileges (also known as SILC operator) on some router. Note
2547 that router operator has router privileges that supersedes the
2548 server operator privileges.
2550 The <username> is the username set in the server configurations
2551 as operator. The <authentication data> is the data that the
2552 client is authenticated against. It may be passphrase prompted
2553 for user on client's screen or it may be public key
2554 authentication data (data signed with private key), or
2557 Difference between router operator and server operator is that
2558 router operator is able to handle cell level properties while
2559 server operator (even on router server) is able to handle only
2560 local properties, such as, local connections and normal server
2563 Reply messages to the command:
2566 Arguments: (1) <Status Payload>
2568 This command replies only with Status Payload.
2573 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2574 SILC_STATUS_ERR_TOO_MANY_PARAMS
2575 SILC_STATUS_ERR_NOT_REGISTERED
2576 SILC_STATUS_ERR_BAD_PASSWORD
2577 SILC_STATUS_ERR_AUTH_FAILED
2580 24 SILC_COMMAND_LEAVE
2583 Arguments: (1) <Channel ID>
2585 This command is used by client to leave a channel the client is
2586 joined to. After a client has leaved the channel the server
2587 must create new key for the channel and distribute to all clients
2588 still currently on the channel.
2590 Reply messages to the command:
2593 Arguments: (1) <Status Payload>
2595 This command replies only with Status Payload.
2600 SILC_STATUS_ERR_NOT_REGISTERED
2601 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2602 SILC_STATUS_ERR_TOO_MANY_PARAMS
2603 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2604 SILC_STATUS_ERR_BAD_CHANNEL_ID
2605 SILC_STATUS_ERR_NO_CHANNEL_ID
2608 25 SILC_COMMAND_NAMES
2611 Arguments: (1) <Channel ID>
2613 This command is used to list user names currently on the requested
2614 channel; argument <Channel ID>. The server must resolve the
2615 user names and send a comma (`,') separated list of user names
2616 on the channel. Server or router may resolve the names by sending
2617 SILC_COMMAND_WHOIS commands.
2619 If the requested channel is a private or secret channel, this
2620 command must not send the list of users, as private and secret
2621 channels cannot be seen by outside. In this case the returned
2622 name list may include a indication that the server could not
2623 resolve the names of the users on the channel.
2625 Reply messages to the command:
2628 Arguments: (1) <Status Payload> (2) <name list>
2630 This command replies with the comma separated list of users on
2636 SILC_STATUS_ERR_NOT_REGISTERED
2637 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2638 SILC_STATUS_ERR_TOO_MANY_PARAMS
2639 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2640 SILC_STATUS_ERR_BAD_CHANNEL_ID
2641 SILC_STATUS_ERR_NO_CHANNEL_ID
2642 SILC_STATUS_ERR_NOT_ON_CHANNEL
2647 Currently undefined commands.
2650 255 SILC_COMMAND_MAX
2652 Reserved command. This must not be sent.
2657 5.3 SILC Command Status Types
2660 5.3.1 SILC Command Status Payload
2662 Command Status Payload is sent in command reply messages to indicate
2663 the status of the command. The payload is one of argument in the
2664 command thus this is the data area in Command Argument Payload described
2665 in [SILC2]. The payload is only 2 bytes of length. Following diagram
2666 represents the Command Status Payload (field is always in MSB order).
2672 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
2673 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2675 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2679 Figure 5: SILC Command Status Payload
2683 o Status Message (2 bytes) - Indicates the status message.
2684 All Status messages are described in the next section.
2689 5.3.2 SILC Command Status List
2691 Command Status messages are returned in the command reply messages
2692 to indicate whether the command were executed without errors. If error
2693 has occured the status tells which error occured. Status payload only
2694 sends numeric reply about the status. Receiver of the payload must
2695 convert the numeric values into human readable error messages. The
2696 list of status messages below has an example human readable error
2697 messages that client may display for the user.
2699 List of all defined command status messages following.
2702 Generic status messages:
2706 Ok status. Everything went Ok. The status payload maybe
2707 safely ignored in this case.
2709 1 SILC_STATUS_LIST_START
2711 Start of the list. There will be several command replies and
2712 this reply is the start of the list.
2714 2 SILC_STATUS_LIST_END
2716 End of the list. There were several command replies and this
2717 reply is the last of the list. There won't be other replies
2718 beloning to this list after this one.
2722 Currently undefined and has been reserved for the future.
2725 Error status message:
2727 10 SILC_STATUS_ERR_NO_SUCH_NICK
2729 "No such nickname". Requested nickname does not exist.
2731 11 SILC_STATUS_ERR_NO_SUCH_CHANNEL
2733 "No such channel". Requested channel name does not exist.
2735 12 SILC_STATUS_ERR_NO_SUCH_SERVER
2737 "No such server". Requested server name does not exist.
2739 13 SILC_STATUS_ERR_TOO_MANY_TARGETS
2741 "Duplicate recipients. No message delivered". Message were
2742 tried to be sent to recipient which has several occurrences in
2745 14 SILC_STATUS_ERR_NO_RECIPIENT
2747 "No recipient given". Command required recipient which was
2750 15 SILC_STATUS_ERR_UNKNOWN_COMMAND
2752 "Unknown command". Command sent to server is unknown by the
2755 16 SILC_STATUS_ERR_WILDCARDS
2757 "Wildcards cannot be used". Wildcards were provided but they
2760 17 SILC_STATUS_ERR_NO_CLIENT_ID
2762 "No Client ID given". Client ID were expected as command
2763 parameter but were not found.
2765 18 SILC_STATUS_ERR_NO_CHANNEL_ID
2767 "No Channel ID given". Channel ID were expected as command
2768 parameter but were not found.
2770 19 SILC_STATUS_ERR_BAD_CLIENT_ID
2772 "Bad Client ID". Client ID provided were erroneous.
2774 20 SILC_STATUS_ERR_BAD_CHANNEL_ID
2776 "Bad Channel ID". Channel ID provided were erroneous.
2778 21 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2780 "No such Client ID". Client ID provided does not exist.
2784 22 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2786 "No such Channel ID". Channel ID provided does not exist.
2788 23 SILC_STATUS_ERR_NICKNAME_IN_USE
2790 "Nickname already exists". Nickname created could not be
2791 registered because number of same nicknames were already set to
2792 maximum. This is not expected to happen in real life but is
2795 24 SILC_STATUS_ERR_NOT_ON_CHANNEL
2797 "You are not on that channel". The command were specified for
2798 client user is not currently on.
2800 25 SILC_STATUS_ERR_USER_ON_CHANNEL
2802 "User already on channel". User were invited on channel they
2805 26 SILC_STATUS_ERR_NOT_REGISTERED
2807 "You have not registered". User executed command that requires
2808 the client to be registered on the server before it may be
2811 27 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2813 "Not enough parameters". Command requires more parameters
2816 28 SILC_STATUS_ERR_TOO_MANY_PARAMS
2818 "Too many parameters". Too many parameters were provided
2821 29 SILC_STATUS_ERR_PERM_DENIED
2823 "Your host is not among the privileged". The client tried to
2824 register on server that does not allow this host to connect.
2826 30 SILC_STATUS_ERR_BANNED_FROM_SERVER
2828 "You are banned from this server". The client tried to register
2829 on server that has explicitly denied this host to connect.
2833 31 SILC_STATUS_ERR_BAD_PASSWORD
2835 "Cannot join channel. Incorrect password". Password provided for
2836 channel were not accepted.
2838 32 SILC_STATUS_ERR_CHANNEL_IS_FULL
2840 "Cannot join channel. Channel is full". The channel is full
2841 and client cannot be joined to it.
2843 33 SILC_STATUS_ERR_NOT_INVITED
2845 "Cannot join channel. You have not been invited". The channel
2846 is invite only channel and client has not been invited.
2848 34 SILC_STATUS_ERR_BANNED_FROM_CHANNEL
2850 "Cannot join channel. You have been banned". The client has
2851 been banned from the channel.
2853 35 SILC_STATUS_ERR_UNKNOWN_MODE
2855 "Unknown mode". Mode provided by the client were unknown to
2858 36 SILC_STATUS_ERR_NOT_YOU
2860 "Cannot change mode for other users". User tried to change
2861 someone else's mode.
2863 37 SILC_STATUS_ERR_NO_CHANNEL_PRIV
2865 "Permission denied. You are not channel operator". Command may
2866 be executed only by channel operator.
2868 38 SILC_STATUS_ERR_NO_SERVER_PRIV
2870 "Permission denied. You are not server operator". Command may
2871 be executed only by server operator.
2873 39 SILC_STATUS_ERR_NO_ROUTER_PRIV
2875 "Permission denied. You are not SILC operator". Command may be
2876 executed only by router (SILC) operator.
2878 40 SILC_STATUS_ERR_BAD_NICKNAME
2880 "Bad nickname". Nickname requested contained illegal characters
2883 41 SILC_STATUS_ERR_BAD_CHANNEL
2885 "Bad channel name". Channel requested contained illegal characters
2888 42 SILC_STATUS_ERR_AUTH_FAILED
2890 "Authentication failed". The authentication data sent as
2891 argument were wrong and thus authentication failed.
2896 6 Security Considerations
2898 Security is central to the design of this protocol, and these security
2899 considerations permeate the specification.
2905 [SILC2] Riikonen, P., "SILC Packet Protocol", Internet Draft,
2908 [SILC3] Riikonen, P., "SILC Key Exchange and Authentication
2909 Protocols", Internet Draft, June 2000.
2911 [IRC] Oikarinen, J., and Reed D., "Internet Relay Chat Protocol",
2914 [SSH-TRANS] Ylonen, T., et al, "SSH Transport Layer Protocol",
2917 [PGP] Callas, J., et al, "OpenPGP Message Format", RFC 2440,
2920 [SPKI] Ellison C., et al, "SPKI Certificate Theory", RFC 2693,
2923 [PKIX-Part1] Housley, R., et al, "Internet X.509 Public Key
2924 Infrastructure, Certificate and CRL Profile", RFC 2459,
2927 [Schneier] Schneier, B., "Applied Cryptography Second Edition",
2928 John Wiley & Sons, New York, NY, 1996.
2930 [Menezes] Menezes, A., et al, "Handbook of Applied Cryptography",
2933 [OAKLEY] Orman, H., "The OAKLEY Key Determination Protocol",
2934 RFC 2412, November 1998.
2936 [ISAKMP] Maughan D., et al, "Internet Security Association and
2937 Key Management Protocol (ISAKMP)", RFC 2408, November
2940 [IKE] Harkins D., and Carrel D., "The Internet Key Exhange
2941 (IKE)", RFC 2409, November 1998.
2943 [HMAC] Krawczyk, H., "HMAC: Keyed-Hashing for Message
2944 Authentication", RFC 2104, February 1997.
2956 EMail: priikone@poseidon.pspt.fi