Configuring PuTTY for X forwarding

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The X Window System, aka X11 or simply X, provides a mechanism that allows you to have the graphical user interface (GUI) for an application running on a remote system to be displayed on the system on which you are running X server software. For systems running a Microsoft Windows operating system, you can use the free PuTTY program to establish a Secure Shell (SSH) connection to an SSH server and configure PuTTY to allow X forwarding so that you can run programs on the SSH server, but have their GUI displayed on the Microsoft Windows system on which you are running PuTTY. To configure PuTTY for X forwarding, load a saved session in PuTTY, then under Category on the left side of the PuTTY window, select X11, then check the check box for "Enable X11 forwarding".

PuTTY enable X11 forwarding

Then click on Session under Category and then click on Save to save the session configuration with the newly selected option. If you have X server software, such as Xming running on the Microsoft Windows system from which you established the SSH connection with PuTTY, you can start a graphical application, such as the Mozilla Thunderbird email client, on a remote system, e.g., a Linux server, and have the program's GUI appear on the Windows system running PuTTY. E.g., after you established an SSH connection to the Linux server with PuTTY, you could issue the command below at a shell prompt to start Thunderbird on the Linux server, but have the GUI for the program displayed on the Windows system.

$ thunderbird &
[1] 437
[testacct@moonpoint ~]$
(process:437): GLib-CRITICAL **: g_slice_set_config: assertion 'sys_page_size == 0' failed

$

If you put the ampersand (&) at the end of the line, you can have the program run in the background on the Linux server and you can return to the shell prompt by hitting Enter.