RE: Reproducing the cygwin X problems

["Phil Betts" <Phil dot Betts at ascribe dot com>]

Mike Ayers wrote:
> 	Today I noticed a new problem, which may or may not be related:
> 
> [SNIP]
> mike-ayers-lap> ssh -Y -l mayers mikeayers-linux-2
> Warning: No xauth data; using fake authentication data for X11
> forwarding.
> Last login: Thu Feb 19 11:54:55 2009 from 192.168.2.87
> mikeayers-linux-2> export DISPLAY=192.168.2.87:0
> mikeayers-linux-2> xterm
> Xlib: connection to "192.168.2.87:0.0" refused by server
> Xlib: No protocol specified
> 
> xterm Xt error: Can't open display: 192.168.2.87:0
> mikeayers-linux-2>
> [/SNIP]
> 
> 	This same technique used to work.  The only changes I have made
> since it last worked was (1) update cygwin, including X, and (2) add "
> -- -multiwindow -clipboard" to my invocation of startx (I used to get
> those by default).
> 

It might have worked, but it was wrong.  Do not set the DISPLAY
environment variable.  It is set by ssh -Y to something similar to
"localhost:10.0" - the actual value depends on whether there are other
forwarded X connections to that box.

BEFORE running ssh, you need to ensure that $DISPLAY is set correctly
for local connections (probably ":0").

By specifying your own value for $DISPLAY inside the ssh session, you 
are ensuring that all X traffic bypasses the ssh tunnel and sets up its 
own (insecure and not encrypted) connection.  This new connection must 
then go through the normal authentication process and it will appear 
to the X server as a remote connection, whereas the ssh connection 
looks like a local connection to the server.

Phil
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