RE: SSH Notes

[Alexander Gottwald <Alexander dot Gottwald at informatik dot tu-chemnitz dot de>]

Harold Hunt wrote:
> That doesn't make any sense.  ssh picks up the DISPLAY value on your Cygwin
> host because it needs to know where to direct the data that comes in over
> the X11 tunnel.  So, a DISPLAY of 127.0.0.1 on your Cygwin host can only
> cause ssh to try to connect to the X Server on your Cygwin host ---
> 127.0.0.1 does not mean that ssh will try to connect to the remote host's
> local X Server.

But how do you know that the Xserver on the cygwin host was run the user? 
Maybe he is also logging in (to the cygwin host) via ssh or telnet.

> 
> My point is, why on earth did the user run ``ssh -X [...]'' if they did not
> want to actually enable X11 tunnelling?  

/etc/ssh/ssh_config might contain "ForwardX11 yes". Now you confuse all
users which want to use only ssh but don't have a xserver running.

> I would say it is a pretty safe
> assumption that they want to use the X Server on their Cygwin host to
> display the tunnelled data.  Most users are entirely confused when they run
> ``ssh -X [...]'' and X11 tunnelling does not actually get enabled.  We
> should not be making users jump through any hoops to use X11 tunnelling.

I don't think it is a good idea to do some implict configuration changes
and I don't expect that such a patch would ever reach the openssh cvs.

SuSE has a similar thing in their default .profile

if test -z "$DISPLAY" -a "$TERM" = "xterm" -a -x /usr/bin/who ; then
    WHOAMI="`/usr/bin/who am i`"
    _DISPLAY="`expr "$WHOAMI" : '.*(\([^\.][^\.]*\).*)'`:0.0"
    if [ "${_DISPLAY}" != ":0:0.0" -a "${_DISPLAY}" != " :0.0" \
         -a "${_DISPLAY}" != ":0.0" ]; then
        export DISPLAY="${_DISPLAY}";
    fi
    unset WHOAMI _DISPLAY
fi

And there are a lot of cases where this does not work and you search a 
long time for error.

> > If users want DIPLAY explicitly set they can add it to their .profile
> >
> 
> Are we talking about the same type of users?  :)

No I don't think so. I still expect some kind of clevernes from the user *g*
But I know we can't expect it for all windows users :(

-- 
 Alexander.Gottwald@informatik.tu-chemnitz.de 
 http://www.gotti.org           ICQ: 126018723