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Thread: screen sharing?

  1. #1
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    screen sharing?

    Hi.
    I have a PC, a laptop and a raspberry pi 4, all running Ubuntu 19.10 (yes, I installed a GUI on the pi). Now I want to share the pi's desktop with the other 2 (and preferably between the computers too). So I turned on screen sharing in the control panel on one computer and tried to connect to it from the other one using remmina but all attempts failed. A youtube video mentioned that i have to turn off encryption. But turning off encryption is simply not an option.

    So what can I do?
    Is there any software that lets me use screen sharing with encryption enabled?
    I TNO, therefore I am.

  2. #2
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    Re: screen sharing?

    ssh -X user@pi4 /path/to/program

  3. #3
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    Re: screen sharing?

    I was talking about screen sharing, not ssh.
    I TNO, therefore I am.

  4. #4
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    Re: screen sharing?

    Quote Originally Posted by hmiersch View Post
    I was talking about screen sharing, not ssh.
    Remote X11 will display almost all applications running on a remote system to the local machine. Using ssh w/ X11 tunnelling just makes it easier. I use this method every day, all day, to run programs on other systems, but display the window on my current desktop. That's what the provided command accomplishes.

    Another secure method, x2go, doesn't work on ARM platforms. It also uses ssh tunnels. Not all programs have been ported to ARM architectures.

    I suppose VNC would work, but because the security for that protocol is so very bad, using ether an ssh-tunnel or full VPN needs to be mandatory. VNC servers should only run a listener on the localhost interface, never any LAN or WAN IP.

    If you just want pure read-only sharing with other systems, any of the 500 WebRTC solutions can work. Zero security.

    In theory, the Gnome3 Desktop Sharing included w/ 19.10 should be production ready. That's the theory. Then there is reality.
    https://help.gnome.org/users/gnome-h...esktop.html.en
    Currently only remote passwordless unencrypted VNC access to an existing session is supported.
    which tells me all I need to know. Avoid.

    Which brings me back to the solution already posted, using remote X11.
    Code:
    ssh -X user@pi4 /path/to/program

  5. #5
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    Re: screen sharing?

    Now that you put it that way, I think it's worth a try. I'll give it a go when I get home...
    I TNO, therefore I am.

  6. #6
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    Re: screen sharing?

    IMHO, remoting a whole desktop, just to overwrite it with an application, is a waste of electrons. Just remote the application using SSH -X as shown above.

  7. #7
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    Re: screen sharing?

    Quote Originally Posted by HermanAB View Post
    IMHO, remoting a whole desktop, just to overwrite it with an application, is a waste of electrons. Just remote the application using SSH -X as shown above.
    Really depends on the available bandwidth, IME. Remote X11 only works well when the systems are connected by 100 Mbps or faster connections. I generally don't have that bandwidth outside the building, so an efficient NX connection like x2go (with proper tuned settings) really becomes necessary. The lack of an ARM port for any NX means I've never used ARM systems in that way, but connecting into the LAN where the ARM system is located using an NX/x2go connection, then using remote X11 for the last hop does work. I also will make the last hop into a Windows RDP session after handling the remote x2go connection between 2 x86 Linux desktops.

    But remote X11 doesn't "share" any desktop or application. It is a 1-client-to-1-server connection. OTOH, x2go does support a 1-to-many-viewers capability, but alas - not with ARM CPUs.

    For text stuff, tmux and screen can share a terminal with multiple users over ssh, so I've heard.

    Until hmiersch tries something, not much more to be answered.

  8. #8
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    Re: screen sharing?

    well, i tried it and it didn't work. first i tried to use the hostname, but that got me error messages. so i started using the IP address instead, and that eliminated the error messages. but it still doesn't work. i entered ssh -X harry@192.168.1.10 /usr/bin/firefox but then nothing happened. no disk activity on the PC, no new window, no error messages, no nothing. i tried the terminal too, with the same result. checking firewall settings now...
    Last edited by hmiersch; March 12th, 2020 at 07:48 PM.
    I TNO, therefore I am.

  9. #9
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    Re: screen sharing?

    a question about UFW: when a connection is initiated, and it allows the packets to go out, does it automatically allow the response packets in or do i need another rule for that?
    I TNO, therefore I am.

  10. #10
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    Re: screen sharing?

    Note that for X forwarding to work over SSH, two things are required:
    a. ssh must be running on the target
    b. Xorg must be installed on both machines (not Wayland)

    Test ssh with:
    $ ssh -vvv user@ipaddress

    Fix that first, before trying forwarding - one thing at a time.

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