Description: Mouse and Keyboard Sharing
Keywords: Virtual Screen, Open Source, Software

### Synergy Frequently Asked Questions

#### Questions

1. Why doesn't ctrl+alt+del work on secondary screens?
2. Can the server and client be using different operating systems?
3. What's the difference between synergy and x2x, x2vnc, etc?
4. What does "Cannot initialize hook library" mean?
5. What security/encryption does synergy provide?
6. What should I call my screens in the configuration?
7. Why do my Caps-Lock, Num-Lock, Scroll-Lock keys act funny?
8. Can synergy share the display in addition to the mouse and keyboard?
9. Can synergy do drag and drop between computers?
10. Do AltGr or Mode-Switch or ISO_Level3_Shift work?
11. Why isn't synergy ported to platform XYZ?
12. My client can't connect. What's wrong?
13. Linking fails on Solaris. What's wrong?
14. The screen saver never starts. Why not?
15. I can't switch screens anymore for no apparent reason. Why?
16. I get the error 'Xlib: No protocol specified'. Why?
17. The cursor goes to secondary screen but won't come back. Why?
18. The cursor wraps from one edge of the screen to the opposite. Why?
19. How do I stop my game from minimizing when I leave the screen?

#### Answers

1. Why doesn't ctrl+alt+del work on secondary screens?

   Synergy isn't able to capture ctrl+alt+del on PC compatible primary screens because it's handled completely differently than other keystrokes. However, when the mouse is on a client screen, pressing ctrl+alt+pause will simulate ctrl+alt+del on the client. (A client running on Windows NT, 2000, or XP must be configured to autostart when the computer starts for this to work.)

   On a primary screen running on an OS X system, you can use ctrl+command+del. Using the pause key isn't necessary since OS X doesn't treat ctrl+command+del differently. And using the pause key isn't usually possible because there isn't one on most OS X systems. Use command instead of option/alt because the command key, not the option/alt key, maps to alt on windows. The reason is because the command key is in the same physical location and performs the same general function (menu shortcuts) as alt on a windows system. This mapping can be modified in the configuration.

   On mac laptops, the key labeled "delete" is actually backspace and ctrl+command+delete won't work. However fn+delete really is delete so fn+ctrl+command+delete will act as ctrl+alt+del on a windows secondary screen.

2. Can the server and client be using different operating systems?

   Yes. The synergy network protocol is platform neutral so synergy doesn't care what operating systems are running on the server and clients.

3. What's the difference between synergy and x2x, x2vnc, etc?

   Unlike x2x, synergy supports any number of computers and it doesn't require X on Microsoft Windows platforms. It also has more advanced clipboard support and synchronizes screensavers. x2vnc is also limited to two computers, requires the separate vnc package, and is really only appropriate for using an X system to control a non-X system. However, the right tool for the job is whatever tool works best for you.

4. What does "Cannot initialize hook library" mean?

   This error can occur on a synergy server running on a Microsoft Windows operating system. It means that synergy is already running or possibly was not shut down properly. If it's running then first end the synergy task. If it's not then try logging off and back on or rebooting then starting synergy again.

5. What security/encryption does synergy provide?

   Synergy provides no built-in encryption or authentication. Given that, synergy should not be used on or over any untrusted network, especially the Internet. It's generally fine for home networks. Future versions may provide built-in encryption and authentication.

   Strong encryption and authentication is available through SSH (secure shell). Run the SSH daemon (i.e. server) on the same computer that you run the synergy server. It requires no special configuration to support synergy. On each synergy client system, run SSH with port forwarding:

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

   where server-hostname is the name of the SSH/synergy server. Once ssh authenticates itself, start the synergy client normally except use localhost or 127.0.0.1 as the server's address. SSH will then encrypt all communication on behalf of synergy. Authentication is handled by the SSH authentication.

   A free implementation of SSH for Linux and many Unix systems is OpenSSH. For Windows there's a port of OpenSSH using Cygwin.

6. What should I call my screens in the configuration?

   You can use any unique name in the configuration file for each screen but it's easiest to use the hostname of the computer. That's the computer name not including the domain. For example, a computer with the fully qualified domain name xyz.foo.com has the hostname xyz. There should also be an alias for xyz to xyz.foo.com. If you don't use the computer's hostname, you have to tell synergy the name of the screen using a command line option, or the startup dialog on Windows.

   Some systems are configured to report the fully qualified domain name as the hostname. For those systems it will be easier to use the FQDN as the screen name. Also note that a Mac OS X system named xyz may report its hostname as xyz.local. If that's the case for you then use xyz.local as the screen name.

7. Why do my Caps-Lock, Num-Lock, Scroll-Lock keys act funny?

   Some systems treat the Caps-Lock, Num-Lock, and Scroll-Lock keys differently than all the others. Whereas most keys report going down when physically pressed and going up when physically released, on these systems the Caps-Lock and Num-Lock keys report going down when being activated and going up when being deactivated. That is, when you press and release, say, Caps-Lock to activate it, it only reports going down, and when you press and release to deactivate it, it only reports going up. This confuses synergy.

   You can solve the problem by changing your configuration file. In the screens section, following each screen that has the problem, any or all of these lines as appropriate:

               halfDuplexCapsLock = true
               halfDuplexNumLock = true
               halfDuplexScrollLock = true

   Then restart synergy on the server or reload the configuration.

8. Can synergy share the display in addition to the mouse and keyboard?

   No. Synergy is a KM solution not a KVM (keyboard, video, mouse) solution. However, future versions will probably support KVM. Hopefully, this will make synergy suitable for managing large numbers of headless servers.

9. Can synergy do drag and drop between computers?

   No. That's a very cool idea and it'll be explored. However, it's also clearly difficult and may take a long time to implement.

10. Does AltGr/Mode-Switch/ISO_Level3_Shift work?

    Yes, as of 1.0.12 synergy has full support for AltGr/Mode-switch. That includes support for most (all?) European keyboard layouts. All systems should be using the same keyboard layout, though, for all characters to work. (Any character missing from a client's layout cannot be generated by synergy.) There is experimental support for ISO_Level3_Shift in 1.1.3.

11. Why isn't synergy ported to platform XYZ?

    Probably because the developers don't have access to platform XYZ and/or are unfamiliar with development on XYZ. Also, synergy has inherently non-portable aspects so there's a not insignificant effort involved in porting.

12. My client can't connect. What's wrong?

    A common mistake when starting the client is to give the wrong server host name. The last synergyc command line option (Unix) or the "Server Host Name" edit field (Windows) should be the host name (or IP address) of the server not the client's host name. If you get the error connection failed: cannot connect socket followed by the attempt to connect was forcefully rejected or connection refused then the server isn't started, can't bind the address, or the client is connecting to the wrong host name/address or port. See the troublshooting page for more help.

13. Linking fails on Solaris. What's wrong?

    Did you add

                --x-includes=/usr/openwin/include --x-libraries=/usr/openwin/lib

    to the configure command line? Solaris puts the X11 includes and libraries in an unusual place and the above lets synergy find them.

14. The screen saver never starts. Why not?

    If the synergy server is on X Windows then the screen saver will not start while the mouse is on a client screen. This is a consequence of how X Windows, synergy and xscreensaver work.

15. I can't switch screens anymore for no apparent reason. Why?

    This should not happen with 1.1.3 and up. Earlier versions of synergy would not allow switching screens when a key was down and sometimes it would believe a key was down when it was not.

16. I get the error 'Xlib: No protocol specified'. Why?

    You're running synergy without authorization to connect to the X display. Typically the reason is running synergy as root when logged in as non-root. Just run synergy as the same user that's logged in.

17. The cursor goes to secondary screen but won't come back. Why?

    Your configuration is incorrect. You must indicate the neighbors of every screen. Just because you've configured 'Apple' to be to the left of 'Orange' does not mean that 'Orange' is to the right of 'Apple'. You must provide both in the configuration.

18. The cursor wraps from one edge of the screen to the opposite. Why?

    Because you told it to. If you list 'Orange' to be to the left of 'Orange' then moving the mouse off the left edge of 'Orange' will make it jump to the right edge. Remove the offending line from the configuration if you don't want that behavior.

19. How do I stop my game from minimizing when I leave the screen?

    Many full screen applications, particularly games, automatically minimize when they're no longer the active (foreground) application on Microsoft Windows. The synergy server normally becomes the foreground when you switch to another screen in order to more reliably capture all user input causing those full screen applications to minimize. To prevent synergy from stealing the foreground just click "Options..." and check "Don't take foreground window on Windows servers." If you turn this on then be aware that synergy may not function correctly when certain programs, particularly the command prompt, are the foreground when you switch to other screens. Simply make a different program the foreground before switching to work around that.