XDMCP through a NAT firewall.

["John McEntee" <jmcentee at stirling-dynamics dot com>]

I need a fairly simple X server using XDMCP, that has one vital function, it
can work from behind NAT! I would much prefer this to be a GPL based X
server as well.

I have a windows destop with the ipaddress 192.168.0.1
I also have an ADSL router with ipadress 192.168.0.254 on the local LAN and
216.239.59.147 on the internet.
I want to connect to 72.14.205.19 with XDMCP.

The command
Xwin.exe -ac -from 216.239.59.147 -query 72.14.205.19
fails with an error message of
Xserver: failed to bind to -from address: 216.239.59.147

My understanding of the problem.
Although I can get the ADSL router to NAT 192.168.0.1 to 216.239.59.147 so
the packet from 192.168.0.1 to 72.14.205.19 have the from address is
216.239.59.147. I understand the inital UDP 177 packet embeds the
192.168.0.1 address. This results in the remote server (72.14.205.19)
sending the response to the windows desktop (192.168.0.1) which it cannot
reach. I wish to be able to embed the router/firewall (216.239.59.147)
ipaddress in the orginal conection from the windows desktop 192.168.0.1 so
the remote server (72.14.205.19) replies to the router/firewall
(216.239.59.147)


How easy would it be to change the source code of Xwin.exe to do this?

Thanks

John

P.S. x11 Tunnelling with ssh is not a option. The above ipaddress are
complete fiction, and the connection is actually a private WAN link which
reduces the security concerns.


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