Re: problems with accessing X apps with ssh
On Fri, 2007-03-30 at 01:14 +0200, Nigel Henry wrote:
> I have to admit that I am confused when discussing clients, and servers with
> working with SSH.
>
> Anyway here goes. I can ssh from Etch (192.168.0.8) to either FC1
> (192.168.0.228), or FC2 (192.168.0.230), and get stuff from Etch displayed on
> the CLI on FC1, and 2, and also get X apps, gedit for example displayed.
>
> The other way from FC1, or FC2, ssh'ing to debian, I can can ssh into Debian
> (192.168.0.8), and view anything I want on the CLI, but have problems with
> opening X apps.
>
> In /etc/ssh/ssh_config I have tried changing "ForwardX11" no to yes, and have
> also tried changing "ForwardX11Trusted" from no to yes, and obviously
> uncommenting them, but still no success.
>
> These are the sort of complaints I get when trying to access Etch from FC1, or
> FC2. SSH'ing into Etch isn't the problem. The CLI stuff works ok, it's just
> the X apps that complain. See below.
>
> Last login: Thu Mar 29 22:23:34 2007 from 192.168.0.228
> djmons@debian:~$ gedit
> cannot open display: (null)
> Run 'gedit --help' to see a full list of available command line options.
> djmons@debian:~$ kwrite
> kwrite: cannot connect to X server
> djmons@debian:~$ cheesetracker
> cheesetracker: cannot connect to X server
> djmons@debian:~$
>
> This is all I get, and doesn't say anything.
>
> So this is the way it stands at the moment. I can ssh from Etch into FC1, or
> FC2, access the CLI on Etch, and also open Xapps.
>
> Going the other way from FC1, or FC2 to Etch. I can access the CLI on Etch ok,
> but cannot access any Xapps.
>
> All a bit puzzling.
Okay. You local GUI is the X-Server. It runs the display and all the GUI
functions associated with it.
When you execute a GUI application it becomes an X-Server client. It
sends display info to the X-Server. The X-Server Renders it. In this
case there is no remote machine.
Now, let us say, you have your FC2 machine which you are sitting at. It
has the X-Server running the GUI display. Let us call this the local
machine. You have another machine sitting in the Data Center... lets
call this the remote machine. In actuality you consider this to be the
server, as all the *work* gets done there. Well, it is and it isn't.
*IF* you want to display a GUI application on your local machine, the
remote machine is then a client to your X-Server. This is were most
people get confused. X is opposite of what you regularly think of. The
GUI application started on the "server" is in reality a client to the
X-server or the local GUI Display.
Okay, try this form your FC2 machine:
ssh -X debian
The -X tells ssh to ask for an X forwarded session and sets a remotely
local $DISPLAY, usually with an X offset of 10 or 20, so it look like:
DISPLAY=localhost:10
This is an X forwarded display on the remote machine to send all input
to your local X-Server.
Now right after that:
gedit &
You should now get a gedit window on your local display which is the *X
Server*. Remember gedit is an X-client (remote) to your X-Server
(local).
Now, remember this. If you want to automagically have this on Debian
machine you sit at and use as an X-Server, you will need to set the
config to carry the "-X" as a default.
On the machine you sit at(the local machine)... the
"/etc/ssh/ssh_config" will have to have a line like this:
ForwardX11 yes
On the machine you ssh into (the remote machine), you will need to make
sure an entry in "/etc/ssh/sshd_config" has entries that look like this:
X11Forwarding yes
X11DisplayOffset 10
after changing the sshd_config, you will have to restart the openssh
server using "/etc/init.d/ssh restart"
It they both do not conform to these settings, you will not be able to
get displays working the way you want.
Remember please do not confuse the two files on the local and remote
machines. They are:
/etc/ssh/ssh_config on the local machine.
/etc/ssh/sshd_config on the remote machine.
If you still have issues, please respond back to this e-mail.
--
greg, greg@gregfolkert.net
I don't mow my lawn anymore. I just intimidate it into not growing.
Though it is quite hard to intimidate grass, it has been around a long time
and has quite an attitude about it.
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