Black screen when attempting to connect via vncviewer

[PascalDutch]

When we are trying to connect with vncviewer to a remove server running Xvnc, we get a black screen. This is only the case when a physical display is connected. When there is no display connected we are able to get to the GDM login screen and enter our credentials. After that, we get the error "ccon: end of stream". How can we fix this?

Below is our configuration.

 /etc/systemd/system/vnc-server.socket:
[Unit]
Description=VNC server for Per-Connection Servers
[Socket]
ListenStream=127.0.0.1:5901  
Accept=true
MaxConnections=10
[Install]
WantedBy=graphical.target

/etc/systemd/system/vnc-server@.service:

[Unit]
Description=Remote desktop service (VNC)
After=syslog.target network.target
[Service]
Type=simple
ExecStart=/usr/bin/Xvnc -inetd -query localhost -once securitytypes=none -SendCutText=0 -AcceptCutText=0 -IdleTimeout=600
StandardInput=socket
StandardOutput=journal
StandardError=journal
[Install]
WantedBy=graphical.target

We are connecting with:

vncviewer localhost:1 -via <server>

vncviewer version: TigerVNC Viewer 64-bit v1.8.0

Xvnc version: Xvnc TigerVNC 1.8.0

Underlying X server release 11905000

Thanks in advance.

[Pierre Ossman]

On 19/01/2022 16:35, PascalDutch wrote:
> When we are trying to connect with vncviewer to a remove server running
> Xvnc, we get a black screen. This is only the case when a physical display
> is connected. When there is no display connected we are able to get to the
> GDM login screen and enter our credentials. After that, we get the error
> "ccon: end of stream". How can we fix this?
>

That sounds like your desktop environment is terminating right away.
Have you checked the journal if there are any errors there?

Regards
--
Pierre Ossman Software Development
Cendio AB https://cendio.com
Teknikringen 8 https://twitter.com/ThinLinc
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Phone: +46-13-214600

A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?

[PascalDutch]

Sorry for the late reply. We checked the journal with below output:

[root@srv-1]# journalctl -u *vnc*
Jan 26 08:26:17 srv-1 systemd[1]: Started Remote desktop service (VNC) (127.0.0.1:43172).

Jan 26 08:26:17 srv-1 systemd[1]: Starting Remote desktop service (VNC) (127.0.0.1:43172)...

[root@srv-1]# journalctl -u *gdm*
Jan 26 08:26:45 srv-1 gdm[3710]: Failed to remove greeter program access to the display. Trying to proceed.

[root@srv-1]# journalctl -u *polkit*
Jan 26 08:26:21 srv-1 polkitd[1366]: Registered Authentication Agent for unix-session:c3 (system bus name :1.10288 [/usr/bin/gnome-shell], object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8)
Jan 26 08:26:45 srv-1 polkitd[1366]: Unregistered Authentication Agent for unix-session:c3 (system bus name :1.10288, object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8) (disconnected from bus)

Also, logging in directly on the server (via ssh or physical display) does work. It fails when we use “vncviewer localhost:1 -via srv-1”

Thanks.

With kind regards,

Pascal

Op vrijdag 21 januari 2022 om 16:48:39 UTC+1 schreef Pierre Ossman:

[Pierre Ossman]

On 26/01/2022 09:54, PascalDutch wrote:
> Sorry for the late reply. We checked the journal with below output:
>
> [root@srv-1]# journalctl -u *vnc*
> Jan 26 08:26:17 srv-1 systemd[1]: Started Remote desktop service (VNC)
> (127.0.0.1:43172).
> Jan 26 08:26:17 srv-1 systemd[1]: Starting Remote desktop service (VNC)
> (127.0.0.1:43172)...
>
> [root@srv-1]# journalctl -u *gdm*
> Jan 26 08:26:45 srv-1 gdm[3710]: Failed to remove greeter program access to
> the display. Trying to proceed.
>
> [root@srv-1]# journalctl -u *polkit*
> Jan 26 08:26:21 srv-1 polkitd[1366]: Registered Authentication Agent for
> unix-session:c3 (system bus name :1.10288 [/usr/bin/gnome-shell], object
> path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8)
> Jan 26 08:26:45 srv-1 polkitd[1366]: Unregistered Authentication Agent for
> unix-session:c3 (system bus name :1.10288, object path
> /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8)
> (disconnected from bus)
>

Unfortunately nothing obvious there.

1.8.0 is a very old version of TigerVNC, so it's difficult for us to
support. Have you reported this issue to your distribution?