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Running X window graphical application over ssh session

SSH, server has feature called X11Forwarding. It specifies whether X11 forwarding is permitted or not. You need to set this parameter to yes. Once this is enabled, you will be able to run a graphical application on server and get applications display (window) on your desktop.

Server setup
For example, login on Linux/BSD system called server1.mydomain.com. Open /etc/ssh/sshd_config file using text editor:

# vi /etc/ssh/sshd_config

Find out parameter X11Forwarding and set it to yes:

X11Forwarding yes

Save file and exit to shell prompt. Restart sshd service under Debian Linux:

# /etc/init.d/ssh restart

Alternatively, if you are using Fedora / Red Hat Linux restart sshd:

# /etc/init.d/sshd restart

Desktop setup
Since X11 forwarding is enabled, just login from desktop system to server1.mydomain.com using ssh command:

desktop $ ssh -X user@server1.mydomain.com

server1 $
When you login using ssh command, you need to use -X flag to enable X11 forwarding. If you do not use -X flag forwarding it will not work and you will get an error that read as follows:
couldn't open display (null)

Once you are logged in to server1, if you type the X application command over ssh session, the application will run on server1 and display will appear on your desktop system. For example, run xeyes or open office program:

server1 $ xeyes &
server1 $ ooffice &

Within few seconds, you should get a graphical display on your desktop system.

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{ 5 comments… add one }

  • Anonymous April 22, 2006, 12:50 pm

    Replace -X with -Y for a trusted/encrypted session :-j

  • Lifeboy June 3, 2008, 9:21 am

    Great article! Hoe would one achieve the same if there is another machine inbetween like this:
    Desktop -> WRT54GL (OpenWrt) -> Server. I know there is a way one can forward packets via ssh, but how?

    Thanks again.

  • anon July 22, 2008, 1:21 am

    Hi all,
    can we make some changes in the sshd config file so that everytime we don’t have to specify -X or -Y option for opening a graphical interface??

  • Marmalade March 28, 2009, 10:10 am

    in the file

    you can add

    Host ahost
    ForwardX11 yes

    to always enable for that host

    or use

    Host *
    ForwardX11 yes

    to always enable it

  • ashutoshh singh November 11, 2013, 4:51 pm

    is there any solution if a program like firefox is already open at server , then as a clinet if i try to open firefox then it shows the program is already running.

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