SILC - Secure Internet Live Conferencing ======================================== [NOTE: SILC is still in middle of development and this package is known as Developer's Version which means that the package is in no means stable or ready to be in production use. This package is for those who wants to test SILC, find bugs and maybe contribute some time and code for the SILC project. There is no guarantees that this package even compiles and even if it compiles there is no guarantees that it would work, and even if it works there is no guarantees that it would work correctly, and even if it seems to work correctly it may be just plain luck.] Description =========== SILC (Secure Internet Live Conferencing) is a protocol which provides secure conferencing services in the Internet over insecure channel. SILC is IRC like softwarre although internally they are very different. Biggest similarity between SILC and IRC is that they both provide conferencing services and that SILC has almost same commands as IRC. Other than that they are nothing alike. Biggest differences are that SILC is secure what IRC is not in any way. The network model is also entirely different compared to IRC. Running SILC ============ The development version is still preliminary version and requires some work to get it working. You should, first of all, check the example configuration files in ./doc/ directory. Change them according to your needs. To run SILC client: cd silc ./silc -f To run SILC server cd silcd ./silcd -f SILC Commands ============= /SERVER [[:]] Connects to remote SILC server. /NICK [] Changes/sets nickname. Note that in SILC there can be multiple same nicknames. However, the logic on working with multiple nicknames on user interface is pretty much still missing. Also note that nicknames in SILC are case-sensitive. /JOIN Joins to a channel. Channel names start with `#' character. /LEAVE Leaves the channel. If /leave * is given the client leaves the current channel. /CMODE +|- [{ }] Changes/sets channel mode. Most of the modes require special privileges, such as channel operator or channel founder privileges to work. The mode is added by adding + before the option(s) and removed by adding - before the option(s). Following modes are available: p Set/unset channel as private channel s Set/unset channel as secret channel k Set/unset that channel uses private channel key i Set/unset channel as invite only channel t Set/unset that only channel operator or founder may set channel topic l Set/unset channel's user limit a Set/unset passphrase for channel that must be provided when joining to the channel. c Set/unset channel's cipher h Set/unset channel's hmac Multiple modes can be set/unset at once if the modes does not require any arguments. If mode requires an argument then only one mode can be set at once. /CUMODE +|- [@] Changes/set user's mode on a channel. Most of the modes require that the client who changes some client's mode must be channel founder or channel operator. Following channel user modes are available: a [@] Set/unset all modes (cannot be used to set both founder and operator rights, can be used only to remove both modes at once). f [@] Unset channel founder. Channel founder rights cannot be set by user (only by server) so this can be used only to unset the mode. o [@] Set/unset channel operator. Requires that you are channel operator or channel founder. /UMODE +|- Sets/unsets user mode. Currently none of the modes can be set by the user so this command can be merely used to unset some mode. Following user modes are available: a Unset all modes s Unset server operator privileges r Unset router operator privileges /MSG Sends private message to remote client. Support for handling multiple same nicknames with /MSG command is still missing. /WHOIS [@] [] Gives a little information about a client. Support for handling multiple same nicknames with this command is still missing. /WHOWAS [@] [] Gives a little history information about a client. /INVITE [[@server>] [+|-[[@[![@hostname>]]]]] Invites client to a channel or manages the invite list of the channel. The first argument is used if an client is invited to the channel. The second +|- argument is used to either add or delete invite from the channel's invite list. Wildcards may be used with this command. /BAN [+|-[[@[![@hostname>]]]]] Manages the ban list of the channel. Wildcards may be used with this command. You must be channel operator to be able to use this command. /KICK [@] [] Kicks client from channel. You have to be at least channel operator to be able to kick client from channel. Note: you cannot kick channel founder even if you are channel operator. /PING [] Pings server. Only locally connected server may be pinged. /INFO [] Requests information about a server. If argument is not specified current server is used. /AWAY [] Sets away message. When private message is received and away message is set the client automatically replies to the sender with the away message. To remove away message give the command without arguments. /QUIT Quits session. Connection to remote server is closed. /CLEAR Clears current screen. /VERSION Shows client version. /OPER [] Obtains server operator privileges. /SILCOPER [] Obtains router operator privileges. /KILL [] Router operator can use this command to remove an client from the SILC Network temporarily. /CONNECT [] Connects to server the remote . You must be server operator to be able to do this. /CLOSE [] Closes connection to the . You must be server operator to be able to do this. /SHUTDOWN Shutdowns the server. You must be server operator to be able to do this. /MOTD [] Display the MOTD of the server. If server is not specified the current server is used. /LIST [] Lists all channels in the current server, or the channel specified. If the channel cannot be found then all channels are listed. /KEY msg|channel set|unset|list|agreement|negotiate [] This command is used to set and unset private keys for channels, set and unset private keys for private messages with remote clients and to send key agreement requests and negotiate the key agreement protocol with remote client. The key agreement is supported only to negotiate private message keys, it currently cannot be used to negotiate private keys for channels, as it is not convenient for that purpose. Types: msg The command is performed for private messages affecting the . channel The command is performed for channel affecting the . Commands: set [ [] []] Set the key into use. If the is provided it is used as the key material. If the is not provided the negotiated key material is used. If the negotiation has not been performed this command has no effect. If the type is `msg' and the is `*' then random key will be generated automatically. The may be set for both private message and channel private keys and the may be set only to the channel private keys. unset [] Unset the key. The private key is not used after this command. The key must be set again or the key material must be re-negotiated to be able to use the private keys again. The channel may have several private keys set. The can be used to indicate what key is being unset. If it is not provided all keys are removed. list List all private keys that has been set. If the type is `msg' and the is ´*' then all private message keys that you've set will be listed. agreement [ []] Send key agreement request to remote client. If the is provided it is sent in the request. The receiver may use the hostname to start the key agreement. If the is also provided your key agreement protocol server is bound to that port. Note that it cannot be privileged port (<1023). If the and is not provided then the receiver will never initiate the key agreement. In this case you must start the key agreement after receiving the reply to the request, by giving the /KEYAGR start command. This command may be used to send reply to the remote client. When receiving empty key agreement you can reply to the sender with the hostname and port of your key agreement server with this command. negotiate [ []] This may be called to start the key agreement with . This command has effect only if the has replied to your key agreement request. You will see a notify on the screen when the reply arrives. The and is the hostname and port of the remote client's key agreement server. /ME This command is used to send an action to the channel. This equals to CTCP's ACTION (IRC's /ME) command. /NOTICE This command is used to send for example informational notice messages to the channel. Features ======== Features to be included into the final release of SILC. [Note that the current Developer's Version does not include all of these features, read TODO file for more information.] o Normal conferencing services such as private messages, channels, channel messages, etc. All traffic is secured and authenticated. o No unique nicknames. There can same nicknames in SILC without collisions. SILC has unique Client ID's, Server ID's and Channel ID's to assure that there are no collisions. o Secure key exchange and authentication protocol. SILC Key Exchange protocol provides key material used in the SILC sessions in secure manner. The protocol is immune for example to man-in-the-middle attacks. The SILC Authentication protocol provides strong authentication. Authentication may be based on passphrase or public key (RSA) authentication. For clients there is an option not to use authentication when connecting to servers. o All traffic is encrypted and authenticated using the best cryptographic algorithms out there. Command messages, private messages and channel messages are all protected by encryption. User can set private keys for both private message and for channels so that even SILC servers do not know the keys. Cipher keys are, by default, 128 bits in length and public keys, by default, 1024 bits in length. o Supports data compression with GZIP to improve performance. o Supports SOCKS4 and SOCKS5 firewall traversal protocols. o SIM (SILC Module) support. Support for loading of shared objects at run-time that provides new and extended features to both SILC client and server. These can provide extra ciphers and extra features to the software. o SILC client can be installed and used without root privileges. o SILC client can be configured by system wide configuration files but with user specific configuration files as well. History ======= Even though SILC were just released to the public the idea and the protocol itself is quite old. I got the idea about SILC in its current form in the year 1996 and first lines of codes were written in early 1997. This release is now third rewrite of the SILC. The very first version were written in 1997 and it included SILC client and very very preliminary SILC server. The server actually weren't usable but the client looked pretty much the same as it does now. At that time the SILC also included RSA implementation and 3DES implementation. The random number generator that exists in this current release is actually based on the RNG written in 1997. The RNG written in 1997, on the other hand, were based on the SSH's random number generator. The RNG has been rewritten twice since the first version. I stopped writing the SILC later in 1997 when I got busy at school and in work. The pause lasted several months. The development resumed in 1998 when my friend (Juha Räsänen) and I implemented ElGamal algorithm. I rewrote some other parts as well. However, for the same reasons as previously the development stopped again. I resumed the development later in 1998 by doing rewrite of the SILC in C++. This was obviously a mistake but at that time it seemed like a good idea. Again, in the winter 1999 I got very busy writing my thesis and was forced to stop the development again. I also, started a new job in the spring. Later, in 1999, I decided that this time I'm going to make it the right way. C++ was obviously a bad choice so I decided to fall back to plain C language. I also decided to do complete rewrite and started doing more thorough planning of what the SILC actually should include. I also decided that this time it is going to kill me before I stop the development. I started writing SILC in the weekends and actually everytime I had some spare time. I also started a new job but I didn't let that get to my way. The result of this development effort is the release now in public. I've learned a lot by doing the SILC. I guess, when I started it I wasn't that good of a C programmer. That alone was a reason why SILC hasn't seen the day of light before now. My programming style has also changed dramatically during these years. Actually, it has changed couple times since this last rewrite as well. However, the code style of current SILC release is quite consistent (actually the coding style SILC has been written now I've learned in my current job). There is probably over 85% of new code in this third rewrite. Rest has just been copied from the old versions and only minor changes has been made (like changed function names and overall coding style). I've preserved the dates of the old files (dating back to 1997) that has existed in some forms in the old versions. There is a lot of new code but already I see a lot that needs rewriting. The development continues. Contact ======= Feedback and comments are welcome. You can reach me in the following Address. Official SILC project web site is : http://silc.pspt.fi FTP archive for SILC project is : ftp://silc.pspt.fi/pub/silc/ Development mailing list address is : silc-devel@lists.sourceforge.net Pekka Riikonen