[Security-Discuss] NAT/SSH Tunneling Alternatives

Hey All,
I'm doing a science project on securing an insecure windows network,
without doing any changes to the windows machines themselves, aside from
altering DNS search order, proxy config, etc. But the problem I have run
into, is:
NAT is too insecure, any good hacker seems to be able to get past it
quite quickly, so I need an alternative to it.
SSH Tunneling requires _way_ to much client side configuration, and
can't forward UDP traffic (as far as I know...).
So, what can one use for this? The linux box is acting as a gateway for
the windows network, it runs a DNS server, DHCP server, samba server,
and a few other utilities. It has 2 NICs and a third cannot be added.
I would prefer that the windows machines not be able to talk to each
other, as all file/print sharing will be done by the linux box.
Thanks!
Danny

____________________________________________________
Want to buy your Pack or Services from MandrakeSoft? 
Go to http://www.mandrakestore.com
Join the Club : http://www.mandrakeclub.com
____________________________________________________