Can't open display w/Cygwin on Win XP

Harold L Hunt II
Mon Jan 20 23:59:00 GMT 2003


Glad I could help.


-----Original Message-----
[]On Behalf Of Robert Gottesman
Sent: Monday, January 20, 2003 11:26 AM
Subject: Re: Can't open display w/Cygwin on Win XP

Harold ..
>>I have a firewall/VNC product installed,
>>but I don't think that is the problem
My most humblest apologies .. You're right!!!(duh).

I have Wingate client installed on my PC which is an app trying to fool my
other PC apps that there is no firewall (there is a Wingate Server .. Acting
as a firewall)

Bottom line .. When I disabled the Wingate client all worked 100%.

A thousand thanx.

-Bob Gottesman

----------- Original Message ---------------------

From: "Harold L Hunt II" <huntharo at msu dot edu>
To: <cygwin-xfree at cygwin dot com>
Date: Sun, 19 Jan 2003 13:28:19 -0500
Subject: RE: Can't open display w/Cygwin on Win XP
Reply-to: cygwin-xfree at cygwin dot com


So, the wording of your question suggests that what you really meant to say
was, ``I have a firewall/VNC product installed, but I don't think that is
the problem.''  Is that the case or not?

If you do have firewall/VNC software installed, I can assure you that it
most likely IS the problem; the fact that other software works fine has no
bearing on whether or not Cygwin/XFree86 will work fine.  You see,
Cygwin/XFree86 is heavily dependent upon TCP/IP working exactly correctly.
Remember, we are not just using the Win32 API for TCP/IP... we are using
Cygwin to emulate the POSIX/UNIX interface to TCP/IP using the Win32 API
TCP/IP calls.  This requires taking advantage of some peculiarities of the
Win32 API TCP/IP interface.  Can you assure us that your firewall/VNC vendor
implemented each and every one of those peculiarities correctly?  If not,
then we just have to assume that the firewall/VNC software is the problem.
We have dealt with this issue several times in the past and the correlation
between Cygwin/XFree86 not working and firewall/VNC software being the blame
is about 100% in cases where firewall/VNC software was ever installed on the

Yeah, that's another little bit about the firewall/VNC software: some of the
vendors are sloppy and their uninstall routines do not replace the original
Win32 API TCP/IP DLLs... they just leave their own in place.  We have had
people that have uninstalled firewall/VNC software and still could not get
Cygwin/XFree86 to work.  Then they reinstalled Windows and Cygwin/XFree86
worked.  As a final test they reinstalled the firewall/VNC software and
Cygwin/XFree86 broke.  They uninstalled the firewall/VNC software and
Cygwin/XFree86 was still broken.

That was all in the mailing list archives, but I felt like writing about it
for some reason.

Hope that helps,


P.S. Oh yeah, and if you have never installed firewall/VNC software on your
Windows machine, then kindly disregard the above.  :)

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