Synergie or KVM

Source
Patches

Running Synergy
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.
Step 1 - Choose a server
The first step is to pick which keyboard and mouse you want to share. The computer with that keyboard and mouse is called the "primary screen" and it runs the synergy server. All of the other computers are "secondary screens" and run the synergy client.
Step 2 - Install the software
Second, you install the software. Choose the appropriate package and install it. For example, on Windows you would run SynergyInstaller. You must install the software on all the computers that will share the mouse and keyboard (clients and server). On OS X you'll just have a folder with some documentation and two programs. You can put this folder anywhere.
Step 3 - Configure and start the server
Next you configure the server. You'll tell synergy the name of the primary and secondary screens, which screens are next to which, and choose desired options. On Windows there's a dialog box for setting the configuration. On other systems you'll create a simple text file.
Note that when you tell synergy that screen A is to the left of screen B this does not imply that B is to the right of A. You must explicitly indicate both relations. If you don't do both then when you're running synergy you'll find you're unable to leave one of the screens.
Windows
On Windows run synergy by double clicking on the synergy file. This brings up a dialog. Configure the server:

• Click the Share this computer's keyboard and mouse (server) radio button
• Click the Screens & Links Configure... button
• Click the + button to add the server to the Screens list
  • Enter the name of server (the computer's name is the recommended name)
  • Optionally enter other names the server is known by
  • Click OK
• Use the + button to add your other computers
  • Using a computer's name as its screen name is recommended
  • Choose desired screen options on the Add Screen dialog
• Use the controls under Links to link screens together
  • Click (once) on the server's name in the Screens list
  • Choose the screen to the left of the server; use --- if there is no screen to the left of the server
  • Choose the screens to the right, above and below the server
  • Repeat the above steps for all the other screens
• Click OK to close the Screens & Links dialog
• Use Options... to set desired options
• If the server's screen name is not the server's computer name:
  • Click Advanced...
  • Enter the server's screen name next to Screen Name
  • Click OK

Now click Test. The server will start and you'll see a console window with log messages telling you about synergy's progress. If an error occurs you'll get one or more dialog boxes telling you what the errors are; read the errors to determine the problem then correct them and try Test again. See Step 5 for typical errors.
Step 5 - Test
Clients should immediately report a successful connection or one or more error messages. Some typical problems and possible solutions are below. See the troubleshooting and the FAQ pages for more help.

• failed to open screen (X11 only)
  Check permission to open the X display;
  check that the DISPLAY environment variable is set
  use the --display command line option.

• address already in use
  Another program (maybe another copy of synergy) is using the synergy port; stop the other program or choose a different port in the Advanced... dialog. If you change the port you must make the same change on all of the clients, too.

• connection forcefully rejected
  The synergy client successfully contacted the server but synergy wasn't running or it's running on a different port. You may also see this if there's a firewall blocking the host or port. Make sure synergy is running on the server and check for a firewall.

• already connected
  Check that the synergy client isn't already running.

• refused client
  Add the client to the server's configuration file.

• connection timed out
  Check that server-host-name is correct.
  Check that you don't have a firewall blocking the server or synergy port.

• connection failed
  Check that server-host-name is correct.

If you get the error "Xlib: No protocol specified" you're probably running synergy as root while logged in as another user. X11 may prevent this for security reasons. Either run synergy as the same user that's logged in or (not recommended) use "xhost +" to allow anyone to connect to the display.
When successful you should be able to move the mouse off the appropriate edges of your server's screen and have it appear on a client screen. Try to move the mouse to each screen and check all the configured links. Check the mouse buttons and wheel and try the keyboard on each client. You can also cut-and-paste text, HTML, and images across computers (HTML and images are not supported on OS X yet).
Step 6 - Run
Once everything works correctly, stop all the clients then the server. Then start the server with the Start button on Windows and without the -f option on Unix and Mac OS X. Finally start the clients similarly. On Windows before clicking Start you may want to set the Logging Level to Warning so the logging window doesn't pop up (because you currently can't close it, just minimize it).
You can also configure synergy to start automatically when your computer starts or when you log in. See the autostart guide for more information.