Questions[vncviewer](ubuntu)

Pretty new to Linux, so my question might be a dummy one. I have ubuntu 20.10 on raspberry Pi 4 (8GB) with Desktop environment. Installed X11VNC and spent some time configuring it. After few hours fighting with it I got it working. However I have an issue, when I establish a connection(tried several different vnc clients, but results is yet the same), my desktop is being duplicated few many times.

Screenshot: https://ibb.co/vwXm3w9

When I click somewhere in the drawn area, it registers it as if I clicked somewhere on the top screen. Basically they are 8-10 mirrors of the main screen.

I have tried for find the configuration of X11VNC tried to play with the settings (try and error) with no luck, tried to reinstall it - no luck...

I am basically new and trying to understand what is causing the problem(duplication) so I could try to search for some solution.

Can someone help me by explaining what is causing the duplication ?

Service Configuration

[Unit]
Description=x11vnc remote desktop server
Requires=display-manager.service
After=display-manager.service network.target syslog.target


[Service]
Type=simple
ExecStart=/usr/bin/x11vnc -display :0 -auth /var/run/lightdm/root/:0 -forever -loop -noxdamage -repeat -rfbauth /home/user/.vnc/passwd -rfbport 5900 -shared -ncache

Restart=on-failure

[Install]
WantedBy=multi-user.target

I want to establish VNC session between RealVNC Viewer in Windows 10 and TightVNC server in Ubuntu 18.04. I want to see from Windows full Ubuntu desktop. I looked at following resources: Configuring a VNC Desktop: Upgrading GUI from classic gnome desktop to newest gnome desktop How to configure VNC server to get full Gnome desktop? vnc service for ubuntu 18.04, no background and menus How to make VNC Server work with ubuntu-desktop without xfce
ubuntu 18.04 VNC Grey screen

I have used various variants of the xstartup file ~/.vnc/xstartup. However, I cannot find any configuration which is working for me. Below you can find example of the xstartup file. Ping is working and I can ssh from Windows to Ubuntu. VNC connection is also working. However, after establishing VNC session from Windows machine, I cannot see anything.I get an empty window with grey background. From Linux machine I use Remmina for connection with similar result. I want to see exactly the same desktop as if I am looking at the Ubuntu machine, but I cannot do that.

I would appreciate your help very much.

    #!/bin/sh

    export XKL_XMODMAP_DISABLE=1
    #xrdb $HOME/.Xresources
    unset SESSION_MANAGER
    unset DBUS_SESSION_BUS_ADDRESS
    #exec /etc/X11/xinit/xinitrc

    [ -x /etc/vnc/xstartup ] && exec /etc/vnc/xstartup
    [ -r $HOME/.Xresources ] && xrdb $HOME/.Xresources
    xsetroot -solid grey
    vncconfig -iconic &
    #dbus-launch --exit-with-session gnome-session &
    #x-terminal-emulator -geometry 80x24+10+10 -ls -title "$VNCDESKTOP Desktop" &
    #x-window-manager &

    gnome-session &
    #sleep4 && gnome-panel &
    #exec gnome-panel-delay
    gnome-panel &
    gnome-settings-daemon &
    metacity &
    #gnome-terminal &
    #nautilus &
    #startxfce4 &
    #startgnome &

I have a 1920x1080 screen connected directly to my Ubuntu 18.04 LTS server.

I am connecting to it via vino (server side) and vncviewer (client side, Win 10). In my client, I have a 1366x768 screen.

Is there any way to adapt the screen resolution for the remote session (i.e., without changing the resolution in the server), so I don't have to scroll in the vncviewer session to access the whole screen?

PS: In the vncviewer connection options there is a tab Screen. There are two check boxes Resize remote session on connect (with a resolution of 1366 x 768 specified) and Resize remote session to the local window They appear to provide for the intended effect, but they do not.

PS2: There is some info on how to do this with vncserver, e.g. below. But I have found none for vino.

https://superuser.com/questions/184338/how-to-change-screen-resolution-of-vnc-server-without-restarting-it

(I am not looking for answers such as "Stop using VNC as it is insecure", nor do I need answers recommending different VNC implementations, as I'm specifically wanting to get TigerVNC to function properly).

I need to display and control a Ubuntu 18.10 desktop from an Ubuntu 18.10 laptop, using TigerVNC. Both machines have been upgraded to 18.10 recently.

I have enabled desktop sharing on the desktop via the instructions in https://askubuntu.com/a/1088328 with with this exception: When I have not executed the following command:

gsettings set org.gnome.Vino require-encryption false

it does not work (see below). But when I do use that gsettings command on the desktop, then I to get a prompt for the vnc password, and upon typing it in, I'm able to control the desktop. So ultimately, I know that must be the fix, but I specifically need to know why that would be required (see remmina usage below). None of my web searches have provided an answer of why.

On the desktop machine, the Sharing settings are:

Note: I can successfully use the remmina tool, using the VNC setting, to connect to the desktop machine and display it, without using the above gsettings setting on the desktop machine. But, when I use the TigerVNC type of vncviewer using this command:

vncviewer thedesk.local:0

(where thedesk.local is the Ubuntu desktop machine), I get a popup with:

No matching security types

And the output into the shell shows:

$ vncviewer thedesk.local:0

TigerVNC Viewer 64-bit v1.9.0
Built on: 2018-07-29 13:31
Copyright (C) 1999-2018 TigerVNC Team and many others (see README.rst)
See http://www.tigervnc.org for information on TigerVNC.

Sun May 26 07:10:29 2019
 DecodeManager: Detected 8 CPU core(s)
 DecodeManager: Creating 4 decoder thread(s)

Sun May 26 07:10:30 2019
 CConn:       connected to host thedesk.local port 5900

Sun May 26 07:10:31 2019
 CConnection: Server supports RFB protocol version 3.7
 CConnection: Using RFB protocol version 3.7
 CConnection: No matching security types
 CConn:       No matching security types

On both the Ubuntu 18.10 laptop and the desktop machines, I have these installed versions of vnc-like packages, apt remove-ing all other flavors of "vnc" clients/servers to avoid confusion with the Linux "alternatives" mechanism:

$ dpkg --list *vnc* | grep '^i'
ii  libvncclient1:amd64                            0.9.11+dfsg-1.1ubuntu0.1     amd64                        API to write one's own VNC server - client library
ii  remmina-plugin-vnc:amd64                       1.2.31.4+dfsg-1ubuntu1       amd64                        VNC plugin for Remmina
ii  tigervnc-common                                1.9.0+dfsg-1                 amd64                        Virtual network computing; Common software needed by servers
ii  tigervnc-standalone-server                     1.9.0+dfsg-1                 amd64                        Standalone virtual network computing server
ii  tigervnc-viewer                                1.9.0+dfsg-1                 amd64                        Virtual network computing client for X
$ vncviewer --version |& head -5

TigerVNC Viewer 64-bit v1.9.0
Built on: 2018-07-29 13:31
Copyright (C) 1999-2018 TigerVNC Team and many others (see README.rst)
See http://www.tigervnc.org for information on TigerVNC.
$ 

remmina --version pops up with a dialog that reads:

1.2.31.4 (git n/a)

The reason remmina is involved is just to show that some client is able to talk to the Ubuntu desktop, just not TigerVNC. I've tried connecting to thedesk.local from a Raspberry Pi 3 B+ running Raspbian and got a different error, but still seemingly involving a similar incompatibility with security protocols between VNC implementations. The error is:

So, what is remmina providing to the X server (or VNC server?) running on display :0 on thedesk.local, that the TigerVNC viewer client (or that RealVNC client running under Raspbian) is not providing?

My web searches turn up results such as https://ubuntuforums.org/showthread.php?t=2384046 which give "Why don't you do 'X' instead?" type of responses, which is a fair observation. But I specifically want to find out why I would have to use the gsettings change just to get TigerVNC viewer to popup the prompt, while remmina does not require it. (When I need to have security, I know how to tunnel traffic over SSH already.)

I've had this issues across multiple machines and multiple versions of Ubuntu desktop (all 10.04 or later). Usually it happens with an old laptop I've put Ubuntu on but now it's happening on my primary dev machine (a quad-core PC recently upgraded to Ubuntu 12.04 desktop). The problem is this - I can connect to the machine and login with the password, the initial screen looks fine but never refreshes. I can see the monitor for the machine across the room and can see the mouse move and the menus pop up but the image of the screen on the PC in front me running the VNC viewer never updates. So the mouse and keyboard commands are working.

• Ubuntu 12.04 Desktop
• Ultra VNC Viewer (also seen with RealVNC's free VNC viewer)
• Desktop Sharing Static IP on eth0; Dynamic ID on eth1

I think it is an Ubuntu config issue because this PC used to work just fine with 9.04, 10.04, and 11.10 (over the past couple of years). I've also had a couple of laptops that used to have this issue with older Ubuntu's but don't with 12.04.

Additional info:

The Win7 PC I'm trying to use to control the Ubuntu PC is connected via 2 DLink 8-port gigabit routers. The Ubuntu laptop I usually control via VNC is typically only connected to the network via wireless. The screen refresh is choppy but usable. I've repeated the issue on a Win7 laptop which was connected via ethernet and wireless.