Trouble configuring Windows Server Enterprise as a NAT router

Giganews Newsgroups
Subject: Trouble configuring Windows Server Enterprise as a NAT router
Posted by:  Zenexer (Zenex…@discussions.microsoft.com)
Date: Sun, 12 Apr 2009

I recently upgraded my home server to Windows Server 2008 Enterprise R2 Beta.
As I was setting it up, I got the bright idea to replace my router with the
server.  So I got to work installing a second NIC, disabling DHCP/DNS on my
router, etc.  All went well--until I tested it.  I cannot, for the life of
me, get NAT to work.  I have two NICs in my server: one for LAN, another for
WAN.  The WAN NIC is connected via ethernet to a standard broadband modem and
works fine; I can successfully access the internet from the server.  The LAN
NIC is connected (also via ethernet) to a wireless and wired router.  The
router was already configured to behave as a standard switch, as I had
previously used the modem as the DHCP/DNS server (it's one of those
modem-router combos--can't complain, it was free).  DHCP is a go: anything
that connected wirelessly to the network gets a proper IP, with the server
marked as the Def.GW and DNS server.  Now, here's where the problems
start--that's the only thing that works.  I can ping the server just fine,
but DNS requests fail (they work locally on the server, which is configured
to use 127.0.0.1 as the primary DNS server with 4.2.2.1-6 as backup).
External requests result in a "host unreachable" error.  It seems as though
the switch doesn't understand that it's supposed to forward traffic directed
outside the subnet to the server (10.10.0.1), even though RIP-2B is enabled
on both the server and the router.  I haven't seen any suspicious log entries
or such.  Windows Firewall is 100% disabled.  As far as I can tell, RRAS,
DHCP, and DNS are all configured properly, though the results seem to speak
otherwise.  I have to admit, networking at the hardware level is not my area
of expertise; this is a bit different than working with winsock.  After
programming for years, I never thought anything besides a segfault could
frustrate me on a computer--clearly I was wrong.  I don't know how you
network techies do it.  Does anyone have any tips?  I've worked with Server
2003 quite a bit in the past, so feel free to give directions in terms of
another (similar) OS; I should be able to figure it out.

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