How does systemd know if x11vnc is connected to a client ?

markus-n · 04-04-2014, 01:50 AM

... and how can I overcome it ?

Hi folks,

I am currently trying to set up x11vnc as service started during bootup on Arch Linux.

This is my service file:

Code:

[Unit]
Description=VNC Server for X11
Requires=display-manager.service
After=display-manager.service

[Service]
Type=forking
ExecStart=/usr/bin/x11vnc -rfbauth /etc/x11vnc.pass -rfbport 5900 -display WAIT:0 -auth /var/run/lxdm/lxdm-\:0.auth -forever -bg -o /var/log/x11vnc.log -xkb -noxrecord -noxfixes -noxdamage -nomodtweak

and it almost works.

Almost means: It works if a client connects within 2 minutes. Otherwise, x11vnc gets killed. According to my log file, x11vnc caught signal 15.

The WAIT:0 option is necessary, because otherwise x11vnc my start too fast and fail to connect to x11. With WAIT, it will connect to x11 when the client connects.

I also tried Type=oneshot instead of Type=forking (and without the -bg option).
During the 5 minutes, systemctl status shows "Active (running)", and after that it shows "Failed".

Then I start the service manually with systemd start x11vnc, it freezes until the client connects or the timeout occurs.

I have verified the ExecStart command is correct by directly running it from the shell. This way, it works, no matter when a client connects. Even several hours later is fine.

This means that systemd must know somehow if x11vnc is connected to a client.
How does it know this ? And how can I tell it not to kill it even when there is no client ?

Thanks and Regards
Markus

enorbet · 04-05-2014, 03:29 AM

Sorry to post an alternative rather than a direct fix but I am an ex VNC begrudging lover, having known it was dirty and insecure but having no truly viable alternative in X...... until NOMACHINE. It's built to use SSH. It's nice.

markus-n · 04-05-2014, 10:21 AM

@enorbet
Thank you for the link. I'll have a look at it.

@all
But anyway, I am interested in an answer to my original question, because it is something I want to learn and understand. Maybe I will need it in future for another service ...