XDMCP through a firewall w/ nat

[Robert Mecklenburg <mecklen at comcast dot net>]

I'm trying to connect to a linux machine with kdm and I'm having
trouble.  My configurations are:

linux:
Mandrake 9.2
KDE
ssh configured with X11Forwarding

Windows XP:
ICF disabled
Latest Cygwin X (updated daily)

Linksys Firewall/gateway/hub

- I've successfully configured kdm for remote access and tested it
  from a cygwin host on the linux local lan.

- I've correctly configured ssh (I don't think this matters) and can
  connect from the windows machine through the firewall to the remote
  host and can use ssh -X successfully.  I realize this isn't exact
  relevant, but you never know what someone will ask about.

- The firewall is doing nat (I don't know if this is what all
  firewalls do), so I have a linksys_ip and a windows_ip.

- I've configured my local firewall to pass ports 6000-6020 through
  to my windows host.

- I've tried these configurations unsuccessfully.  With these
  I get no error, but no login window.

  XWin -query $remote_ip
  XWin -query $remote_ip -from $windows_ip
  XWin -query $remote_ip -clipboard -from $windows_ip


  With these I get the same error:

  XWin -query $remote_ip -from $linksys_ip
  XWin -query $remote_ip -clipboard -from $linksys_ip
  XWin -query $remote_ip -fp tcp/$remote_ip:7100 -clipboard -from $linksys_ip

  _XSERVTransmkdir: Owner of /tmp/.X11-unix should be set to root
  Fatal server error:
  Xserver: failed to bind to -from address: 24.10.217.117


  With this I get a more hopeful error:


  XWin -query $remote_ip -fp tcp/$remote_ip:7100 -clipboard -from $windows_ip

  Could not init font path element tcp/207.88.121.38:7100, removing from list!
  Fatal server error:
  could not open default font 'fixed'


  I could be I'm not running a font server on port 7100, or that the
  port is inaccessible for some reason.

I've read many of the posting in the archives and the faq.  The faq
says none of this will work through a firewall, but maybe it's out
of date.  I've noticed other posting from people who may have gotten
this to work?  Or have I misread them?

Am I totally off-base?  Is there any hope getting kdm through my
firewall?  Suggestions?

BTW, Thanks for Cgywin and the XFree86 port!  I've been using it for
year with great success.

Thanks,
Robert Mecklenburg