barrier/FAQ

Synergy Frequently Asked Questions
==================================

Questions
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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 CapsLock and NumLock 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 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?

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

    Synergy isn't able to capture ctrl+alt+del on PC compatible
    systems 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 running as a service for this to work.)

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
    called OpenSSH is available from http://www.openssh.com/.  For
    Windows there's a port of OpenSSH using Cygwin
    (http://www.cygwin.com/).

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.

7.  Why do my CapsLock and NumLock keys act funny?

    Some systems treat the Caps-Lock and Num-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, add either or both of these lines as appropriate:

        halfDuplexCapsLock = true
        halfDuplexNumLock = true

    Then restart synergy on the server.

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 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.)

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.

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

	Did you add `--x-includes=/usr/openwin/include
    --x-libraries=/usr/openwin/lib' (without the linebreak) 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 sometimes happens but all the causes aren't yet known.  One
    known cause is if the synergy server in running on Windows
    95/98/Me and a 16-bit application is in the foreground when the
    screen saver starts.  Windows fails to notify synergy that the
    screen saver has started in this situation (which is a bug in
    Windows, not synergy) and synergy may intercept some keyboard
    input and divert it to a client when the screen saver is running.
    As a result, it's possible for the server system to believe a key
    is pressed when it really isn't.  Typically, it's the return key
    and simply tapping it will allow synergy to switch screens again.
    
    If this problem happens to you, try tapping the enter key to see
    if that solves the problem.  If not, you can try running with
    debug logging (--debug DEBUG) and synergy will report exactly why
    it refuses to switch screens.  If it claims a key is down then
    try tapping that key and see if that solves the problem.