synergys(1) synergy server


synergys [ -a address | --address address ] [ -c pathname | --config pathname ] [ --crypto-pass password ] [ -d level | --debug level ] [ --display display ] [ --daemon | { --no-daemon | -f } ] [ -l log-file | --log log-file ] [ -n screen-name | --name screen-name ] [ --no-tray ] [ --no-xinitthreads ] [ --restart | { --no-restart | -1 } ] address

synergys { -h | --help }

synergys --version


Starts the synergys mouse/keyboard sharing server.

Synergy lets you use one keyboard and mouse across multiple computers. To do so it requires that all the computers are connected to each other via TCP/IP networking. Most systems come with this installed.

This manual page was written for the Debian distribution because the original program does not have a manual page.


-a address --address address
listen for clients on the given address.

The argument for --address is of the form: [hostname][:port]. The hostname must be the address or hostname of an interface on the system. The default is to listen on all interfaces. The port overrides the default port, 24800.

-c pathname --config pathname
use the named configuration file instead.

If no configuration file pathname is provided then the first of the following to load sets the configuration:

  • ~/.synergy.conf
  • /etc/synergy.conf

If no configuration file can be loaded then the configuration uses its defaults with just the server screen.

--crypto-pass password
use password as the password for authenticating to the synergy server.
-d level --debug level
filter out log messages with priority below level.

Debug levels are from highest to lowest: FATAL, ERROR, WARNING, NOTE, INFO, DEBUG, DEBUG1, and DEBUG2. Only messages at or above the given level are logged. Messages are logged to a terminal window when running in the foreground, and to syslog when running as a daemon.

--display display
connect to the X server at display
run the server as a daemon.
-f --no-daemon
run the server in the foreground.
-l log-file --log log-file
write log messages to log-file
-n screen-name --name screen-name
use screen-name instead of the hostname to identify this screen in the configuration.

This option lets the client use a name other than its hostname for its screen.

disable the system tray icon.
disable Xlib threading support.

This option may fix some crashing issues with Synergy.

restart the server automatically if it fails.
-1 --no-restart
do not try to restart the server if it fails for some reason.
-h --help
display help and exit.
display version information and exit.


The synergy server requires configuration. The configuration file is a plain text file broken into sections. Each section has the form:

      section: <name>

Comments are introduced by `#' and continue to the end of the line. The file can have the following sections. The `screens' section must appear before the `links' and `aliases' sections.


<args> is a list of screen names, one name per line, each followed by a colon. Names are arbitrary strings but they must be unique. The hostname of each computer is recommended. There must be a screen name for the server and each client. Each screen can specify a number of options. Options have the form `name = value' and a listed one per line after the screen name.


        section: screens
        ~~~~halfDuplexCapsLock = true
        ~~~~halfDuplexNumLock = true
        ~~~~meta = alt

This declares three screens named: moe, larry, and curly. Screen `larry' has half-duplex caps lock and num lock keys (see below) and screen `curly' converts the meta modifier key to the alt key.

Screen can have the following options:

  • halfDuplexCapsLock = {true|false}

    This computer has a caps lock key that doesn't report a press and a release event when the user presses it but instead reports a press event when it's turned on and a release event when it's turned off. If caps lock acts strangely on all screens then you may need this option on the server screen. If it acts strangely on one screen then that screen may need the option.

  • halfDuplexNumLock = {true|false}

    This is identical to halfDuplexCapsLock except it applies to the num lock key.

  • xtestIsXineramaUnaware = {true|false}

    This option works around a bug in the XTest extension when used in combination with Xinerama. It affects X11 clients only. Not all versions of the XTest extension are aware of the Xinerama extension. As a result, they do not move the mouse correctly when using multiple Xinerama screens. This option is currently true by default. If you know your XTest extension is Xinerama aware then set this option to false.

  • Modifier keys:

    shift = {shift|ctrl|alt|meta|super|none}

    ctrl = {shift|ctrl|alt|meta|super|none}

    alt = {shift|ctrl|alt|meta|super|none}

    meta = {shift|ctrl|alt|meta|super|none}

    super = {shift|ctrl|alt|meta|super|none}

    Map a modifier key pressed on the server's keyboard to a different modifier on this client. This option only has an effect on a client screen; it's accepted and ignored on the server screen.

    You can map, say, the shift key to shift (the default), ctrl, alt, meta, super or nothing. Normally, you wouldn't remap shift or ctrl. You might, however, have an X11 server with meta bound to the Alt keys. To use this server effectively with a windows client, which doesn't use meta but uses alt extensively, you'll want the windows client to map meta to alt (using `meta = alt').


<args> is a list of screen names just like in the `screens' section except each screen is followed by a list of links, one per line. Each link has the form `<left|right|up|down> = <name>'. A link indicates which screen is adjacent in the given direction.


        section: links 
        ~~right = larry
        ~~up~~~~= curly
        ~~left  = moe
        ~~up~~~~= curly
        ~~down~~= larry

This indicates that screen `larry' is to the right of screen `moe' (so moving the cursor off the right edge of moe would make it appear at the left edge of larry), `curly' is above `moe', `moe' is to the left of `larry', `curly' is above `larry', and `larry' is below `curly'. Note that links do not have to be symmetrical; moving up from moe then down from curly lands the cursor on larry.


<args> is a list of screen names just like in the `screens' section except each screen is followed by a list of aliases, one per line *not* followed by a colon. An alias is a screen name and must be unique. During screen name lookup each alias is equivalent to the screen name it aliases. So a client can connect using its canonical screen name or any of its aliases.


        section: aliases

Screen `larry' is also known as `' and can connect as either name. Screen `curly' is also known as `shemp'. (Hey, it's just an example.)


<args> is a list of lines of the form `name = value'. These set the global options.


        section: options
        ~heartbeat = 5000
        ~switchDelay = 500

You can use the following options:

  • heartbeat = N

    The server will expect each client to send a message no less than every N milliseconds. If no message arrives from a client within 3N seconds the server forces that client to disconnect.

    If synergy fails to detect clients disconnecting while the server is sleeping or vice versa, try using this option.

  • switchDelay = N

    Synergy won't switch screens when the mouse reaches the edge of a screen unless it stays on the edge for N milliseconds. This helps prevent unintentional switching when working near the edge of a screen.

  • switchDoubleTap = N

    Synergy won't switch screens when the mouse reaches the edge of a screen unless it's moved away from the edge and then back to the edge within N milliseconds. With the option you have to quickly tap the edge twice to switch. This helps prevent unintentional switching when working near the edge of a screen.

  • screenSaverSync = {true|false}

    If set to false then synergy won't synchronize screen savers. Client screen savers will start according to their individual configurations. The server screen saver won't start if there is input, even if that input is directed toward a client screen.

The synergy server will try certain pathnames to load the configuration file if the user doesn't specify a path using the `--config' command line option. `synergys --help' reports those pathnames.


Run the server on the computer that has the keyboard and mouse to be shared. You must have prepared a configuration file before starting the server. The server should be started before the clients but that's not required.

Run the synergy server on the server system using the following command line:

synergys -f [ --config config-pathname ]

Replace config-pathname with the path to the configuration file. See OPTIONS for the default locations of the configuration file. The `-f' option causes synergys to run in the foreground. This is recommended until you've verified that the configuration works. If you didn't include the system's hostname in the configuration file (either as a screen name or an alias) then you'll have to add `--name screen-name' to the command line, where screen-name is a name in the configuration file. You can use `synergys --help' for a list of command line options.

See `Starting Automatically on Unix' below for running synergy automatically when the X server starts.


Synergy requires an X server. That means a server must be running and synergy must be authorized to connect to that server. It's best to have the display manager start synergy. You'll need the necessary (probably root) permission to modify the display manager configuration files. If you don't have that permission you can start synergy after logging in via the .xsession file.

To start the server use something like:

killall synergys

synergys [ <options> ] --config <config-pathname>

<options> must not include `-f' or `--no-daemon'. If the configuration pathname is one of the default locations then you don't need the `--config' option.

Note that some display managers (xdm and kdm, but not gdm) grab the keyboard and do not release it until the user logs in, for security reasons. This prevents a synergy server from sharing the mouse and keyboard until the user logs in.


By default, Synergy does not secure its communications in any way. This is dangerous, as all clipboard and mouse and keyboard events (e.g. typed passwords) are easily examined by anyone listening on the network.

To turn on encryption and authentication support, use the --crypto-pass option on both client and server. In this mode, the connection will be encrypted, and the server will check the client's password against the one it was started with.

If this level of security is not sufficient for some reason (see the BUGS section below for a possible reason), you can use SSH (secure shell) to provide strong authentication and encryption to synergy. SSH is available on Debian systems in the "openssh-server" and "openssh-client" packages, or from On Windows you can use the Cygwin version of OpenSSH.

ssh -f -N -L
server-hostname:24800 server-hostname

where server-hostname is the name or address of the SSH and synergy server host. 24800 is the default synergy port; replace it with whichever port you use if you don't use the default. Once ssh authenticates with the server, start the synergy client as usual except use `localhost' or `' for the server address. Synergy will then pass all communication through SSH which encrypts it, passes it over the network, decrypts it, and hands it back to synergy. Authentication is provided by SSH's authentication.


The cryptography support is fairly new, and to the extent it has been tested, it has not done well. Users are advised to further secure their synergy sessions using methods such as the SSH method described in the NETWORK SECURITY section above until its security has been verified independently.


~/.synergy.conf, /etc/synergy.conf


This manual page was written by Daniel Lutz <[email protected]> for the Debian system. Edited by Titus Barik <[email protected]> and Jeff Licquia <[email protected]>.