X11 forwarding works on Ubuntu using Windows 10 cmd-line ssh only after first using Putty

Question

Note: X11 forwarding works fine if I use putty and X11 forwarding using localhost:0.0. I would like to get it to work using Windows 10 command line ssh. Here are my steps.

• My Windows 10 computer and my Ubuntu computer are on the same local network.
• I installed and ran Xming. The icon in my icon tray says Xming Server:0.0
• I open a command window (type cmd)
• I use ssh -X mymachine and log in ok.
• At my Ubuntu prompt, I type

export DISPLAY=localhost:0.0
xcalc

• I get the following message

No protocol specified
Error: Can't open display: localhost:0.0

• I tried other combinations (Note: Windows 10 computer is on 192.168.1.18)

export DISPLAY=localhost:0.0
export DISPLAY=192.168.1.18:0.0
export DISPLAY=192.168.1.18:0
export DISPLAY=10:0.0
export DISPLAY=10:0.0.1

I even tried typing the following in the Windows command window:

set DISPLAY=localhost:0.0
ssh -X mymachine

but Windows didn't like that. I also tried using Windows Powershell. Nothing worked. I kept getting the same message.

Answer 1

I finally figured it out. I used Putty again and checked the $DISPLAY variable and got:

echo $DISPLAY
localhost:10.0

I just used the value 10.0 and it worked for both the cmd-shell and the Powershell.

But get this ... I tried the same thing the next day (after a restart on both machines) and it did not work.

I used ssh -X mymachine and logged in typed xcalc and got the same error message.

(My $DISPLAY was set in my .bash_profile so I didn't need to reset it.)

I then tried Putty again, and it worked and $DISPLAY was set to localhost:10.0

I then returned to the open cmd-shell and typed xcalc and it worked. I didn't do anything in that shell window prior. Here is the output

adrian@MyMachine:~$ xcalc
Error: Can't open display: localhost:10.0
adrian@MyMachine:~$ echo $DISPLAY
localhost:10.0
adrian@MyMachine:~$ xcalc
adrian@MyMachine:~$

It appears that Putty is doing something globally that has an effect on other shells without the need to reload. How is that so?

Answer 2

Xming Server:0.0 on Windows 10 computer with IP address 192.168.1.18

so the only way to connect to this X11-Server will be to

export DISPLAY=192.168.1.18:0.0

If there are still problems, check if you have enabled X11-forwarding in your putty client. You will find this under Putty Configuration > Connection > SSH > X11 Don't forget to save the Session after setting the X11-forwarding if you plan to use this setting more than one time. Session > Saved Sessions (put in name for your session) > Save

There is also the possiblity to run into a problem with the Xming Server. Right-click the Xming Server icon in the taskbar and view log. If there is a line "IP address not permitted" you will have to edit the file X0.hosts in the installation folder of Xming. Add the IP address of you Linux machine.

Answer 3

This worked for me:

Local (Windows 10, Xming server)

Server (Raspberry Pi 4, RaspberryPi OS)

Ssh Client (Windows native ssh client)

Open windows command prompt and type set DISPLAY=localhost:0.0, then ssh -Y user@ip. Use -X for untrusted session. Works just fine.