KB 216005 - Enabling X11 Forwarding on Ubuntu 22.04 to Run qluman-qt from a Head Node

KB 216005 - Enabling X11 Forwarding on Ubuntu 22.04 to Run qluman-qt from a Head Node

Objective

This article provides step-by-step instructions to enable X11 forwarding on a head node running Ubuntu 22.04 server edition and how to access GUI applications like qluman-qt from a login node using SSH with X11 forwarding.

Edit SSH Server Configuration on the Head Node

Open the SSH daemon config file:
  1. sudo nano /etc/ssh/sshd_config

Ensure the following lines are present and not commented (#):

  1. X11Forwarding yes
X11DisplayOffset 10
X11UseLocalhost no

💡 X11UseLocalhost no is optional but may help in some environments where forwarding does not work properly with localhost.

Save and exit (Ctrl+O, Enter, Ctrl+X).


Restart SSH Service


Apply the changes:
  1. sudo systemctl restart ssh

Confirm Display Environment on the Head Node

Log in directly or via remote terminal to the head node and check the DISPLAY variable:
  1. echo $DISPLAY

Expected output (example):

  1. localhost:10.0

If DISPLAY is set, X11 forwarding is active in your session.

Accessing qluman-qt via X11 Forwarding


From Your Login Node or Workstation

Then connect to the head node with X11 forwarding and launch the application:

  1. ssh -X root@servername qluman-qt
​
Replace servername with your head node’s hostname or IP.