XDISPLAY over SSH with Putty & Xming/VcXsrv

Quick article about how to transfer GUI display on local machine over SSH using PuTTY (or KiTTY) and XServer like Xming/VcXsrv.

On local Windows

X Server

Install one of the X Server below on your local Windows:

• Xming : Slower but lighter than VcXrv (https://sourceforge.net/projects/xming/)
• VcXsrv: Heavier but faster than Xming (https://sourceforge.net/projects/vcxsrv/)

Once install, just click on the program recently installed and a X logo (as below) will appear on the bottom right notification icons.

It means that the XServer is running in the background.

SSH/Telnet client

Install one of theses SSH/Telnet client on your local Windows:

• Putty (https://www.chiark.greenend.org.uk/~sgtatham/putty/latest.html)
• KiTTY (http://kitty.9bis.net/)

Run the program, and configure it as follow:

Under Connection > SSH > X11 :

• Check Enable X11 forwarding
• Enter localhost:0 for "X display location"
• Check MIT-Magic-Cookie-1

Under Session:

• Select SSH
• Select "Default Settings"
• Click Save button

On remote Linux

SSH session

From your local Windows, Open ssh remote session on your Linux machine with PuTTY/KiTTY

• Check that MIT-MAGIC-COOKIE-1 key has been added with: xauth list
• Make sure DISPLAY is set to: export DISPLAY=localhost:10
• Try to display something like: xclock & (if not present, install it with yum install xorg-x11-apps.x86_64)

# Check if MIT-MAGIC-COOKIE-1 key has been added 
[user@oralab01]$ xauth list
    oralab01.uxora.com/unix:10  MIT-MAGIC-COOKIE-1  1a1f7af9b7ca3c11183b529e51529e51

# Make sure DISPLAY variable is set
[user@oralab01]$ env | grep DISPLAY=
    DISPLAY=localhost:10.0

# Display a x11 gui app
[user@oralab01]$ xclock &

An xclock like below should display on your windows desktop :

Tips

SU command

After a su command, you may have the following error if you try to xdisplay something:

    KiTTY X11 proxy: Unsupported authorisation protocol
    Error: Can't open display: localhost:10.0

su open a new session and it does not transfer the session key, so you'll need to manually add the MIT-MAGIC-COOKIE-1 key after the su command.

# Check if MIT-MAGIC-COOKIE-1 key has been added 
[root@oralab01]$ xauth list
    oralab01.uxora.com/unix:10  MIT-MAGIC-COOKIE-1  1a1f7af9b7ca3c11183b529e51529e51

# Change user with su
[root@oralab01]$ su - oracle

# Add the MIT-MAGIC-COOKIE-1 from previous command
[oracle@oralab01]$ xauth add oralab01.uxora.com/unix:10  MIT-MAGIC-COOKIE-1  1a1f7af9b7ca3c11183b529e51529e51
    xauth:  file /home/oracle/.Xauthority does not exist 

# Check if MIT-MAGIC-COOKIE-1 key has been added 
[oracle@oralab01]$ xauth list
    oralab01.uxora.com/unix:10  MIT-MAGIC-COOKIE-1  1a1f7af9b7ca3c11183b529e51529e51

# Set DISPLAY variable
[oracle@oralab01]$ export DISPLAY=localhost:10

# Display a x11 gui app
[oracle@oralab01]$ xclock &

Or you can use the following command before executing the su command:

    su - oracle -c "xauth add $(xauth list | grep MIT-MAGIC-COOKIE-1 | head -1)"
    su - oracle

Or do not use su, but open a new PuTTY/KiTTY session and login with the right user.

Missing charsets warning

    Warning: Missing charsets in String to FontSet conversion
    Warning: Unable to load any usable fontset

If you encounter this warning, set export LC_ALL=C to remove it.

HTH,
Michel.

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