Help locally displaying KDE desktop via x11vnc piped through ssh from Tumbleweed headless remote PC?

[oldcpu]

I am getting an "Authorization required, but no authorization protocol specified" when unsuccessfully trying to connect to a Tumbleweed headless workstation via x11vnc piped through ssh (to locally display the remote Tumbleweed's KDE display).

I've successfully been doing the same identical access method (with commands below) for over a decade with various versions of openSUSE.

Most recent success, using this method, on this identical headless PC, was less than 2 days ago, accessing this same headless PC from a different PC (which is running openSUSE-LEAP-15.2), successfully accessing the x11vnc server running on LEAP-15.3 on this headless PC. Now instead it fails with Tumbleweed installed on the headless PC.

I note the previous success (with LEAP-15.3) displayed locally the KDE desktop from the remote headless PC.

Background: I 'updated' the headless PC's LEAP-15.3 to Tumbleweed yesterday. I can no longer pipe x11vnc via ssh, as I constantly get the noted error (after sending the lengthy 'ssh' command which I note below). As best I can determine, XWindow is running on this headless Tumbleweed display (despite it being headless). The "only" thing changed was the update from LEAP-15.3 to Tumbleweed. Here is what I believe to be the salient part in the bash shell after sending the 'ssh/x11vnc command':

12/01/2022 13:27:42 XOpenDisplay(":0") failed.
12/01/2022 13:27:42 Trying again with XAUTHLOCALHOSTNAME=localhost ...
Authorization required, but no authorization protocol specified

To confirm LEAP-15.2 not the issue, on my LEAP-15.3 laptop, I also tried/failed to display the remote headless Tumblweed PC's KDE display, obtaining identical errors.

When the remote PC had LEAP-15.3 (instead of Tumbleweed), this is the command that I used previous to successfully obtain a remote KDE display:

ssh -t -L 5900:localhost:5900 oldcpu@xxx.xxx.x.xxx 'x11vnc -localhost -nolookup -nopw -ncache 10 -noxdamage -display :0'

where xxx.xxx.x.xxx has an IP address that I am not showing here.

and on the same PC to view the KDE display sent via ssh from the headless workstation:

vncviewer encodings "tight copyrect hextile" localhost:0

as noted that worked yesterday, locally showing the remote's KDE display, when this "Tumbleweed" remote headless PC instead had LEAP-15.3 on it.

My guess is something has changed wrt xauthority between LEAP-15.3 and Tumbleweed, resulting in this techinque that I have been using for more than a decade to no longer function. I suspect this PC being 'headless' is not the issue, but rather it is something new in Tumbleweed?

I would like to fix this without switching to a different vnc method, if possible (as my review of openSUSE forum vnc help threads suggests that trying a different vnc app (which I prefer not do do) is the most common suggestion).

I don't know if I know the correct question to ask ... but the one question that comes to my mind is how do I specifify the correct authorisation protocol?

I don't know if relevant, but as near as I can determine, the KDE Tumbleweed on a headless PC uses ssdm display manager. I note that access to this remote Tumbleweed PC via "ssh -X" works ok and I can run apps on the headless Tumbleweed PC (and display the apps locally).

But I would like to be able to remotely display the full KDE desktop, just like I did a couple of days ago (when it was LEAP-15.3) using x11vnc piped via ssh.

I have surfed a bit on this ... and I wonder if this is a Tumbleweed bug that maybe has not been reported ( https://unix.stackexchange.com/quest...ocol-specified ) ... or is this just me screwing up ?
.

[dcurtisfra]

My guess is something has changed wrt xauthority between LEAP-15.3 and Tumbleweed, resulting in this techinque that I have been using for more than a decade to no longer function. I suspect this PC being 'headless' is not the issue, but rather it is something new in Tumbleweed?

I took a look at the “x11vnc” man page – <https://linux.die.net/man/1/x11vnc> –

• It ain't short but, it's fairly concise …

Are you absolutely certain that, a new (Tumbleweed) configuration parameter at the (headless) x11vnc server end of the connection isn't needed?

---

or is this just me screwing up ?

Unlikely …

[malcolmlewis]

Hi
Just to be sure, the headless system is starting X11 rather than Wayland?

[oldcpu]

I took a look at the “x11vnc” man page – <https://linux.die.net/man/1/x11vnc> –

• It ain't short but, it's fairly concise …

Many thanks for that suggestion. I did spend 30 minutes trawling through that, and a few hours surfing many sites - to no avail.

Purportedly, if one ssh's in, then that ssh tunneling is supposed to provide the needed authentication. And that has been the case for every openSUSE up to and including LEAP-15.3. ... but it fails on Tumbleweed.

Are you absolutely certain that, a new (Tumbleweed) configuration parameter at the (headless) x11vnc server end of the connection isn't needed?

In short, 'NO' ... I am not sure. If there is, approximately 4 hours of surfing yielded nothing to provide evidence that is the case - of course thou I could have missed such. Rarely do I spend that much time on an issue.

But if there is, then Tumbleweed is different than every other openSUSE version prior.

[oldcpu]

Just to be sure, the headless system is starting X11 rather than Wayland?

I looked at the Xorg.log.0 file and spotted nothing to say it was Wayland. Is there anything obvious I should see if it is Wayland? I could have missed such I guess.

[malcolmlewis]

Many thanks for that suggestion. I did spend 30 minutes trawling through that, and a few hours surfing many sites - to no avail.

Purportedly, if one ssh's in, then that is supposed to provide the needed authentication. And that has been the case for every openSUSE up to and including LEAP-15.3. ... but it fails on Tumbleweed.



In short, 'NO' ... I am not sure. If there is, approximately 4 hours of surfing yielded nothing to provide evidence that is the case - of course thou I could have missed such. Rarely do I spend that much time on an issue.

But if there is, then Tumbleweed is different than every other openSUSE version prior.

Hi
There has been a lot of service hardening going on with Tumbleweed, especially with services, you have copied over your ssh key over to the remote system etc?

[oldcpu]

Hi
There has been a lot of service hardening going on with Tumbleweed, especially with services, you have copied over your ssh key over to the remote system etc?

I did not copy anything over. I believe the old key still present. Note I can ssh in without any problem. ssh -X runs fine to open applications on the headless Tumbleweed, and display locally (on different LEAP-15.2 and 15.3 PCs). But trying to get the KDE desktop to display via x11vnc (tunneled via ssh) fails.

[malcolmlewis]

I did not copy anything over. I believe the old key still present. Note I can ssh in without any problem. ssh -X runs fine to open applications on the headless Tumbleweed, and display locally (on different LEAP-15.2 and 15.3 PCs). But trying to get the KDE desktop to display via x11vnc (tunneled via ssh) fails.

Hi
So can you confirm if Plasma is running wayland or X11? Can you try iceWM instead, just to see if it's a system issue or a desktop issue.

[arvidjaar]

12/01/2022 13:27:42 XOpenDisplay(":0") failed.
12/01/2022 13:27:42 Trying again with XAUTHLOCALHOSTNAME=localhost ...
Authorization required, but no authorization protocol specified

...
the KDE Tumbleweed on a headless PC uses ssdm display manager

SDDM is using file with random name to store magic cookie ($XAUTHORITY) instead of default file location and you need to use x11vnc parameter -auth with correct filename. To get it you could use something like this hack:

systemctl --user show-environment  | grep XAUTHORITY= | cut -d'=' -f2

And x11vnc even displays the whole page of hints why connection may have failed after those lines you have shown and that you gratuitously removed. The first thing those hints mention is correct -auth parameter.

[oldcpu]

Hi
So can you confirm if Plasma is running wayland or X11?

I had to surf to figure out how to do that .. ... and when I ssh'd into the PC :

oldcpu@oldcorei7:~> echo $XDG_SESSION_TYPE
tty
oldcpu@oldcorei7:~> 
oldcpu@oldcorei7:~> loginctl show-session $(loginctl show-user $(whoami) -p Display --value) -p Type --value
x11
oldcpu@oldcorei7:~>

... I call this PC "oldcorei7" (as it has a core-i7-920 CPU) . ... So it reads to be X11 running.

Can you try iceWM instead, just to see if it's a system issue or a desktop issue.

Thanks for suggestion. I'll give that I try after I try a few other ideas first.