Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have simple task to do: I have wni7 with two nics.I want to connect another comp(osx) to win7 through second nic to connect it to internet.

  • I already changed the registry.
  • Win7 interface with has no gateway set (no point to do that)
  • OSX interface with has gateway set to
  • I do not add any routes on win7, every thing seems to be already there
  • network on second nic is detected as "undefined network" (probably effect of no gateway)
  • i can achieve any connectivity to internet from OSX only by enabling network connection sharing on nic with, but it enables NAT and I'm interested only in pure routing without nat(it's a setup for some research).
  • firewall is off.

It seems to me that win7 refuses to forward packets for some reason. Perhaps "undefined network" and NLA service is to blame, although i couldn't find any info about that.

Below ascii schematics of my setup:

internet<-->router(<-->( WIN7 (<-->(


share|improve this question
Your router and your Win7 nic have the same IP – JoshP Sep 7 '12 at 17:49
:D Yeah i made error in the the post. it's .2 in realty. – Tomek Sep 7 '12 at 17:59
gotcha... fyi, you can edit your post. There is a little edit button under the tags for your question. – JoshP Sep 7 '12 at 18:02

One way is to share your internet connection. On the WIN7 right klick your "Internet"-NIC selcet properties and switch to "Share" tab. Check the 1rst checkbox and select your 2nd NIC in the dropdown list. Now every client connected on the 2nd NIC gets an ip address by DHCP and your client acts as a router.

share|improve this answer
that's what i did. unfortunately the point is to connect device to osx (ios5) thru wifi on yet another network(ad-hoc wifi) and this new network when routed thru win7 is not translated by nat. messages get to the router but wont come back. I added route to this new network on win7. messages get back to interface and are dropped somewhere in side win7. – Tomek Sep 7 '12 at 11:26

Check that your router has a route to the 192.168.2.x network. Unless you can add one or it is able to discover it your out of luck. It needs a route to tell it to send traffic for 192.168.2.x through the Windows 7 machine acting as a router/gateway at

Make sure routing is enabled on the WIndows 7 machine (do a ipconfig /all at the command prompt and check for a line that says IP Routing Enabled . . . . . . . : Yes. If it's not google for the registry setting to change etc.

share|improve this answer

You need to enable IP routing. Do this by setting the value of the following registry key to 1: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\ Services\Tcpip\Parameters\IPEnableRouter Please verify that this is enabled.

Also, you definitely need to specify a default route on your router! How else should the router decide through which interface traffic to the outside should be sent? It needs this information in the routing table. So, please specify a default gateway on the outside interface. All packets whose destination address does not belong to any of the networks, your router currently is part of will then be sent to the default gateway (i.e. out into the Internet). Does that make sense?

share|improve this answer
Can you perhaps explain the reason, in detail with supporting documentation, that enabling IP forwarding to connected networks solves the author's problem? – Ramhound Dec 2 '15 at 14:19
I don't think that this is the right place for describing details of IP routing. If you need documentation on the registry key, I just found this page on Microsoft's site which describes this to some extent. Please understand that I am not fully sure that my answer can definitely solve the issue. Maybe it doesn't, but it's also not marked as the correct answer, yet. I think it's the purpose of this great site to propose solutions and the correct solution is then marked. I just want to help. And I think down-voting does not help here... – TomS Dec 3 '15 at 9:13
Well I don't find an incomplete answer to be helpful. Perhaps I am actually interested in the reason this key is the solution, understand the mechanics, that requires an explanation. This answer is for everyone in the community also. – Ramhound Dec 3 '15 at 11:12

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.