Re: Info on "Can't open display"

[Stephen Mathezer <mathezer at yahoo dot com>]

I have been watching this thread closely but I haven't piped up until
now because I don't really have a lot to offer.

First off, I have a friend running Windows ME who is encountering
exactly the same symptoms in every detail.  He does not have ANY VPN
software installed on his machine.  THIS PROBLEM IS *NOT* restricted to
VPN users, at least there are quite a few more than 1 (I checked the
archives) without a VPN client that have the problem. I posted a
question on behalf of my buddy a month or so ago and received no response.
Since he isn't on the list and I don't have the problem, I haven't had
much to say on this one as I figured that I can't be of much help.

I do have a few comments though (OK, I got a little long winded below
but I think this thread needs to be brought back to the relevant points)

Kudos to Robert for politely explaining the same things over and over
due to people not reading what he is saying.

I will reiterate a couple of points here, and let me point out that if I
was one of the list regulars/developers I would simply say something
like "check the archives this has been answered before", or maybe I'd
just provide a one-liner url to the archived message.

-Telnet to localhost:6000 is, while not complete in all respects, at
least a decent indication that the VPN client is not doing something as
basic as blocking all connections to localhost:6000 as some seem to
imply. Can somebody please explain to me why TerreTermSSH X forwarding
(see below), displaying remote X clients on the cygwin
server, and telnet to localhost:6000 all work if the VPN software is
truly blocking ports.

-Since the problem occurs even if the VPN client is not running, it is
obviously not some case of the VPN client not allowing split-tunneling
or something like that.  This has to come down to some interaction with
the TCP stack.  Then again, why does adding exceptions to the VPN client
cause things to work even when the client isn't running?

-TeraTermSSH (like any SSH client) can forward X windows connections from
remote machines.  This requires the SSH client running under 98 to
connect to localhost:6000 to proxy the X windows request that it is
forwarding over the encrypted channel from the remote machine.  This has
been repeated ad nauseum on the list.  TeraTermSSH is a perfectly good
example of an X Windows client that works.  That being said, it
certainly would make sense to try another.

-X servers typically (and yes I just checked mine) listen on ALL local
IP addresses (ie *.6000). Clients will connect from some random source
port to port 6000 on $DISPLAY.

I too would have tended to blame the VPN client on this one except for the
fact that other X clients do work.  Trying another X client and another
X server would certainly provide more info.

A couple of things that I haven't seen suggested which may be worth
trying arei:

-Running something similar to ktrace or truss (does sysinternals
 have something similar?) against both client and server.

-Getting debug versions of client and server and running the client
 under GDB and/or attaching to the server and following the logic where
 the connection is failing.

-As has been suggested by othersi, trying other clients to cygwin server
and cygwin clients to other server would be very valuable.


-Steve

_________________________________________________________
Do You Yahoo!?
Get your free @yahoo.com address at http://mail.yahoo.com