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AnArchUser123

Member

Registered: 2020-11-07

Posts: 15

x11vnc not working on login screen GDM

Hello,
Since the latest xorg update. x11vnc doesn't work on GDM. I get the following error message:
Dec 11 16:09:03 PC x11vnc[1032]: caught X11 error:
Dec 11 16:09:03 PC x11vnc[1032]: 11/12/2020 16:09:03 deleted 60 tile_row polling images.
Dec 11 16:09:03 PC x11vnc[1032]: X Error of failed request:  BadAccess (attempt to access private resource denied)
Dec 11 16:09:03 PC x11vnc[1032]:   Major opcode of failed request:  130 (MIT-SHM)
Dec 11 16:09:03 PC x11vnc[1032]:   Minor opcode of failed request:  1 (X_ShmAttach)
Dec 11 16:09:03 PC x11vnc[1032]:   Serial number of failed request:  57
Dec 11 16:09:03 PC x11vnc[1032]:   Current serial number in output stream:  119

Anyone know why?

AnArchUser123

Member

Registered: 2020-11-07

Posts: 15

Re: x11vnc not working on login screen GDM

For anyone else having issues with this you need to make the systemd job run as the GDM user now. X11vnc only starts if it is running as the same user who is running X11.

loveisfoss

Member

Registered: 2021-03-05

Posts: 1

Re: x11vnc not working on login screen GDM

For anyone else having issues with this you need to make the systemd job run as the GDM user now. X11vnc only starts if it is running as the same user who is running X11.

I registered on this forum just to thank you! After reading your solution, I ran my command on the login screen like this and it worked:

"sudo -u Debian-gdm x11vnc -auth /.../... -rfbauth /.../... -display :0"

The user Debian-gdm does not have access to my "-rfbauth" file. But when I run the x11vnc command without it, it works! One just have to find a way to use a password file for the user "Debian-gdm", I am going to look into it.

After hours of troubleshooting and searching your solution came like manna from the sky! Thanks again!

Edit: Solved it completely, one can create a password file for the Debian-gdm user like this:

"sudo -u Debian-gdm x11vnc -usepw"

and then point -rfbauth to it.

Last edited by loveisfoss (2021-03-06 10:23:38)

sergiomb

Member

Registered: 2016-08-14

Posts: 4

Re: x11vnc not working on login screen GDM

Thank you , also is the solution on Fedora 35+

sudo -u gdm x11vnc -localhost -display :0 -auth /run/user/42/gdm/Xauthority

more https://wiki.archlinux.org/title/x11vnc#GDM

Newer GDM packages ship with Xwayland as the default display server backend. The following instructions, however, only apply when using Xorg (else .Xauthority is not created, and x11vnc fails to start). You are therefore advised to uncomment #WaylandEnable=false setting in /etc/gdm/custom.conf in order to proceed.

Last edited by sergiomb (2022-08-12 10:30:49)