shh -X forwarding problem under breezy

[Billy Verreynne (JW)]

Rainer Gutkas wrote:

> ssh -X 99.99.99.199 firefox
>
> one out of ten times I get:(firefox-bin:9981):
> Gtk-WARNING **: cannot open display:

Rainer, it should work..

The times that it does not work usually means a misconfig somewhere.
Or a very weird firewall..

Try the following. ssh into that platform, e.g.
# ssh -X 99.99.99.199

Now look at what the X Display is set to. ssh should set it - however,
ssh sets the environment before the .profile is executed and it in
turn can unset/overwrite the display environment variable.
# echo $DISPLAY

The $DISPLAY var should contain something like:
localhost:10.0

Which means ssh is listening on localhost (127.0.0.1) for X-client
display calls and tunneling that back to the ssh client's X-Server. If
the $DISPLAY reads something else (e.g. just :0.0), then the $DISPLAY
setting was either not set by ssh or was overwritten by something like
a .profile.

Oh yeah - weird firewall. Firewalls usually do not firewall localhost
traffic. They will allow all 127.0.0.1 traffic through (it is after
all, all just local stuff).  But I will not be surprised seeing one
where a bright spark actually went and firewalled localhost, denying a
range of ports.

--
Billy

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