RE: Running remote programs locally

["Andrew Clarke" <spam at clarke dot ca>]

Thanks for the good explanation, Andrew.

- Andrew.

-----Original Message-----
From: cygwin-xfree-owner@cygwin.com
[mailto:cygwin-xfree-owner@cygwin.com] On Behalf Of andrew brian clegg
Sent: Wednesday, August 27, 2003 10:02
To: cygwin-xfree@cygwin.com
Subject: Re: Running remote programs locally




On Wed, 27 Aug 2003, Andrew Clarke wrote:

> Start bash shell
> Run 'xwin &'
> When it comes up, I 'ssh linuxcomputer' and enter my password

You may need to include the -X parameter to ssh unless you've set it up
as a personal default.

> Through vncserver at my root prompt of my linux computer, I type 
> 'xhost
> +windowscomputer'.  I did the same with my windows computer's IP 
> +address
> just to be sure.

I *believe* this only makes a difference to the machine the X server is
running on, in this case your Windows computer.

>  >From the xwin ssh window to my linux computer, I type something 
> simple
> like 'xterm -display windowscomputer:0' and I get the following error:
> 
> Xlib: Connection to "windowscomputer:0.0" refused by server
> Xlib: No protocol specified

The way ssh X forwarding works is by setting up a proxy X server on the
X client machine (your Linux box) that listens on localhost:n (where n
is greater than 0, starts at 10 usually I think). This accepts
connections from X clients e.g. xterms and tunnels them back through ssh
to the real X server at your desktop. The login process should set the
DISPLAY variable for you automatically. If it doesn't there's a sign
something else is up.

e.g. I ssh from home (my Cygwin machine) to college (a Redhat machine).
When I type 

setenv|fgrep DISPLAY

into the shell at college, it tells me

DISPLAY=localhost:10.0

This is the ssh proxy X server's display. If I'd set it manually myself
to say my-home-pc:0.0 then an xterm (or whatever) on starting would
attempt to open a normal, unencrypted TCP/IP connection straight to me
rather than going through ssh.

For the record, I am writing this mail in an xterm on my college server,
which is displaying on my home PC via an ssh tunnel; which is in turn
forwarding its entire desktop as a Terminal Services session via ssh to
my work PC where I sit typing -- because I can ;-)

Andrew.