I started "veyon-server" as a USER directly and got these messages:
08/05/2021 17:42:33 Listening for VNC connections on TCP port 11200
08/05/2021 17:42:33 Listening for VNC connections on TCP6 port 11200
08/05/2021 17:42:33 Xinerama is present and active (e.g. multi-head).
08/05/2021 17:42:33 Xinerama: number of sub-screens: 1
08/05/2021 17:42:33 Xinerama: no blackouts needed (only one sub-screen)
08/05/2021 17:42:33 fb read rate: 305 MB/sec
08/05/2021 17:42:33 fast read: reset -wait ms to: 10
08/05/2021 17:42:33 fast read: reset -defer ms to: 10
08/05/2021 17:42:33 The X server says there are 10 mouse buttons.
08/05/2021 17:42:33 screen setup finished.
The VNC desktop is: localhost:5300
08/05/2021 17:42:33 possible aliases: localhost:11200, localhost::11200
Have you tried the x11vnc '-ncache' VNC client-side pixel caching feature yet?
The scheme stores pixel data offscreen on the VNC viewer side for faster
retrieval. It should work with any VNC viewer. Try it by running:
x11vnc -ncache 10 ...
One can also add -ncache_cr for smooth 'copyrect' window motion.
More info: http://www.karlrunge.com/x11vnc/faq.html#faq-client-caching
08/05/2021 17:42:33 Got connection from client 127.0.0.1
08/05/2021 17:42:33 0 other clients
08/05/2021 17:42:33 check_access: client 127.0.0.1 matches host 127.0.0.1
08/05/2021 17:42:33 incr accepted_client=1 for 127.0.0.1:40640 sock=24
08/05/2021 17:42:33 Client Protocol Version 3.8
08/05/2021 17:42:33 Protocol version sent 3.8, using 3.8
08/05/2021 17:42:33 rfbProcessClientSecurityType: executing handler for type 2
08/05/2021 17:42:33 copy_tiles: allocating first_line at size 33
08/05/2021 17:42:33 Pixel format for client 127.0.0.1:
08/05/2021 17:42:33 32 bpp, depth 24, little endian
08/05/2021 17:42:33 true colour: max r 255 g 255 b 255, shift r 16 g 8 b 0
08/05/2021 17:42:33 no translation needed
08/05/2021 17:42:33 rfbProcessClientNormalMessage: ignoring unsupported encoding type ultraZip
08/05/2021 17:42:33 Using compression level 9 for client 127.0.0.1
08/05/2021 17:42:33 Enabling KeyboardLedState protocol extension for client 127.0.0.1
08/05/2021 17:42:33 Enabling NewFBSize protocol extension for client 127.0.0.1
08/05/2021 17:42:33 Enabling SupportedMessages protocol extension for client 127.0.0.1
Another Client was able to connect now!
So: it runs when the "veyon-server" was started again ... do you have an idea, why it crashes?
First I tried it as root -- but the "veyon-server" didn't start!
X11 MIT Shared Memory Attach failed:
Is your DISPLAY=:0 on a remote machine?
Suggestion, use: x11vnc -display :0 ... for local display :0
caught X11 error:
08/05/2021 17:12:29 deleted 32 tile_row polling images.
X Error of failed request: BadAccess (attempt to access private resource denied)
Major opcode of failed request: 130 (MIT-SHM)
Minor opcode of failed request: 1 (X_ShmAttach)
Serial number of failed request: 60
Current serial number in output stream: 94
@tobydox After further investigation, the student's are able to bypass the firewall. For example, students accounts are prohibited from visiting Reddit.com. However, if the teacher computer is running Veyon, the client can go to Reddit and the firewall records it as traffic under the teachers account. This is a serious issue for us.
If the teacher computer is not turned on, filtering works correctly.
Unfortunately there are limitations by the VNC protocol which could lead to the latencies you've described. Where do you observe the latencies? In the monitoring view with thumbnails or also while remote controlling/viewing a computer?
AFAIK Flatpak does not support systemd services (only systemd user units supported). However the Veyon Service is required to run with root privileges and interact with the systemd logind manager. So all we could package is Veyon Master which wouldn't help that much since you'd always have to install the Veyon Service (and Veyon Configurator) additionally.
oh... Was about to ask the same thing about using a Snap package but I'm guessing it would be the same.