r22 - 25 Jan 2011 - 02:01:31 - ElliottReznyYou are here: TWiki >  CSDocs Web  >  CSLDocumentation > ForwardX11

Forwarding X11

This document describes how to forward X11 to Windows, Linux, or Mac computers. You should be comfortable connecting to CSL computers using an SSH client before trying this. It's beyond the scope of the CSL to support software on personal computers, but these documents should give you a running start.

Using Linux

Most newbie-friendly distributions such as Ubuntu and Debian have OpenSSH? and Xorg preinstalled, XForwarding in Linux is easy as pi, and it's smaller in exact form.

ssh -X <username@><hostname>

The -X flag enables XForwarding. You would type in your username followed by @ if your CS username is different than your username on the computer you're using.

If you're using a less newbie-friendly distribution, are are probably familiar with the requirements to using this command.

Using Windows

Windows requires using an SSH Client, such as PuTTY?, SSH, or SecureCRT?, and an X server, such as Xming Xserver. This will allow X Windows applications to be shown on the display of a Microsoft Windows computer. Start by installing and running the X server, which is generally simple and fast. Once it is running, continue with the SSH Client of your choice.


  • In the Configuration screen:
  • Go to Connection -> SSH -> X11
    PuTTY screenshot 1
  • Select Enable X11 Forwarding
    PuTTY screenshot 2

SSH Secure Shell Client

  • Edit => Settings
    SSH screenshot for step 1

  • A Settings window will pop up. In the left-hand box, under Profile Settings and then under Connection, choose Tunneling. Check the box on the right that says Tunnel X11 connections. Click OK.
    SSH screenshot for step 2

  • It may ask you to save. Click Yes.
    SSH screenshot for step 3


  • Options => Global Options...
    SecureCRT screenshot for step 1

  • A Global Options window will pop up. In the left-hand box, under General choose Default Session. Click the button on the right that says Edit Default Settings....
    SecureCRT screenshot for step 2

  • A Session Options - Default window will pop up. In the left-hand box, under Connection and then under Port Forwarding, choose Remote/X11. Check the box on the right that says Forward X11 Packets. Click OK to successively close the two settings windows.
    SecureCRT screenshot for step 3

  • You will be asked to apply your changes globally. Click Yes.
    SecureCRT screenshot for step 4


Mac OSX is similar to Linux in that it already has an SSH client and an X server running.

ssh -X <username@><hostname>

People may tell you that you should use -Y instead of -X. Why? Because -Y bypasses some security mechanisms. Hence, use it with caution and only if your superior Mac experience tells you to do so.

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