I have set up a number of virtual machines on my Windows 7 - where all the guests are also Windows 7. I hooked up a host-only network adapter to the virtual machines. Since this network is completely isolated from the rest of the world, none of the network interfaces (including the one on my host machine) have a gateway defined. Unfortunately, this has the side effect of Windows marking the interface as "Unidentified network", and applying public network security policy on it.

There is a work-around people suggest for a similar situation that arises in isolated VPNs: define the IP address of a reachable box as the default gateway. This works for the VMs, since I can set the IP address of the host machine as their gateway. Unfortunately, I don't have all the VMs running at the same time. In fact, most of the time, there will only be one of these machines running. Since setting the IP address of the host adapter as the gateway of itself doesn't work, I find myself in a bit of a tricky situation. I can't think of a suitable, reachable IP address to set as the gateway of the host interface.

Is there another way to mark this whole subnet as a private network so that the host machine's firewall will leave my poor virtual machines alone?

  • If your host system doesn't have an IP on that subnet, does this really matter? The Windows firewall mainly works with IP. If no IP is assigned I don't see how any connections could be made that would require a firewall to actually do anything. What are you expecting the firewall to be able to do? – Zoredache Sep 19 '11 at 21:56
  • @Zoredche The host does have an IP address. I want a network between a subset of the VMs and the host machine. But there is no live IP address that I can give as the default gateway to my host's IP address. And all I've seen so far suggests that I need a gateway for windows firewall to get out of the way. – Dysaster Sep 19 '11 at 22:13

I've found a work-around that requires some PowerShell'ing at every reboot. It manually marks the connection as 'Work' even though it is an unidentified network.

The work-around is provided by this answer.

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