gnome-remote-desktop is not listening on port 5900, no sign of why

[Jonathan Kamens]

With all current packages from jammy, gnome-remote-desktop is not listening on port 5900. Lsof doesn't show it listening on that port, attempting to connect to that port yields connection refused), with no indication of why. There are no errors matching the pattern "gnome-remote-desktop" in /var/log/syslog, "journalctl --user --unit gnome-remote-desktop" doesn't show any errors, "systemctl status --user gnome-remote-desktop" shows that it is running, my settings show that screen sharing is enabled, this used to work, and I haven't changed anything since it did.

ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: gnome-remote-desktop 42~rc-1
ProcVersionSignature: Ubuntu 5.15.0-22.22-generic 5.15.19
Uname: Linux 5.15.0-22-generic x86_64
ApportVersion: 2.20.11-0ubuntu79
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: ubuntu:GNOME
Date: Tue Mar 15 10:49:08 2022
InstallationDate: Installed on 2019-01-02 (1167 days ago)
InstallationMedia: Ubuntu 18.10 "Cosmic Cuttlefish" - Release amd64 (20181017.3)
SourcePackage: gnome-remote-desktop
UpgradeStatus: Upgraded to jammy on 2022-02-20 (22 days ago)

[Pascal Nowack (pnowack)]

Me (upstream g-r-d) already predicted this, as soon as I saw that Ubuntu ships mixed versions (gnome-control-center-41 (g-c-c) for GNOME 42 (that's unsupported upstream and as seen here breaks things)).

For GNOME 42, we finally switched over to the RDP backend in g-r-d. As a result the UI in g-c-c has been redesigned (https://gitlab.gnome.org/GNOME/gnome-control-center/-/merge_requests/1205#note_1393775).
To not also unintentionally listen on VNC in the background without the notice of the user, the gsettings were adjusted, so that each g-r-d backend has its internal switch (default: off).

You can check that by checking both g-r-d's and g-c-c's version. Upstream we make sure that things won't break in the major version. This means that all components need to have the same major version (i.e. g-r-d-42 + g-c-c-42 + ...-42). Minor versions are just bugfix releases.

Jeremy and Marco of the Ubuntu Desktop Team are already aware of this from our discussion on IRC. It's up to Ubuntu now to act. The remote desktop is not the only thing that breaks here downstream due to mixed versions.
According to Marco, Ubuntus decision would either be to backport the g-r-d UI changes or adjust their g-c-c build to use VNC again.

Some more info on the RDP backend in 42: https://gitlab.gnome.org/GNOME/gnome-remote-desktop/-/issues/26#note_1396166

[Marco Trevisan (Treviño) (3v1n0)]

We were also tracking this already in https://warthogs.atlassian.net/browse/DT-264

[Burque Computers (burq)]

Any idea if there will indeed be a back port? Or if we're stuck with using VNC?

[Pascal Nowack (pnowack)]

This was fixed in https://bugs.launchpad.net/ubuntu/+source/gnome-control-center/+bug/1968518