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Madiyaan Damha
Asked: 2010-05-30 13:04:50 +0800 CST

Starting x11vnc remotely when X server is already running

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I have a ubuntu linux machine that I have already logged into and X server is running (it is pass the login manager like gdm). I can access this machine through ssh. My goal is to start x11vnc on this machine and attach it to the X server that is already running.

When I ssh into the machine and start x11vnc, it says:

X11 was unable to open the X DISPLAY ":0", it cannot continue.

How can I start x11vnc on the remote machine if I don't have physical access to it and Xserver has already started. The reason I want to do this is because the remote machine has several windows open that I want to work on.

EDIT: I also tried x11vnc -find. This time it didn't give me that error message and was able to detect that the client was connected:

Got connection from client x.x.x.x
...
wait_for_client: find display cmd failed
wait_for_client: bad reply '
'

So it seems like -find command just delays the inevitable.

Thanks,

ssh vnc x11 display

6 Answers

  1. I was using gnome so what I did was simply give x11vnc the x authority file gnome was using. This was done by:

    x11vnc -xauth /var/lib/gdb/:0.Xauth -display :0
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  2. I found on my gentoo kde desktop this works great for when kde is already running.

    x11vnc -xauth /var/run/xauth/A:0-bHJFac -display :0 -passwd "password" -forever -shared

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  3. For me

    Description:    Debian GNU/Linux 6.0.5 (squeeze)
Release:        6.0.5
Codename:       squeeze

apt-cache policy gdm3
gdm3:
  Installiert: 2.30.5-6squeeze4

    this worked well even if i log in remotely via ssh:

    su -c "x11vnc -auth /var/run/gdm3/auth-for-username*/database -display :0 -forever -passwd foo"

    edit: you could also use e.g. ssvnc for a comfortable use of vnc over ssh. Just start the x11vnc like above but with the "-localhost" option:

    su -c "x11vnc -auth /var/run/gdm3/auth-for-username*/database -display :0 -forever -passwd foo -localhost"

    then you can click on "Use SSH" in the ssvnc script and it would connect through ssh, so there is no need for x11vnc to listen globally!

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  4. I solved it in a very roundabout way, so I'm just going to detail how I did it, which is very suboptimal and involved. Others have already given elegant and short solutions.

    The problem I faced was that x11vnc refused to start over SSH saying that it did not find any graphical display. So my solution to that was....

    First, over SSH as root I started a TigerVNC server on the machine at display :1

    # vncserver :1

    (starting as root was stupid)

    Then I connected to this display using TigerVNC from my client computer

    Connect to: a.b.c.d:1

    Now I'm in the GUI as root(very stupid). I opened a terminal, and started x11vnc as my original user

    # sudo -u milind x11vnc -many -display :0

    Now I was able to 

    Connect to: a.b.c.d:0

    Done! albeit in a very roundabout manner.

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  5. Use x0vncserver instead:

    x0vncserver is a TigerVNC Server which makes any X display remotely accessible via VNC, TigerVNC or compatible viewers. Unlike Xvnc(1), it does not create a virtual display. Instead, it just shares an existing X server (typically, that one connected to the physical screen).

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  6. For my situation, my machine was auto logged in as UserX and I was ssh'ed into the machine and running the x11vnc command as UserY

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