Couldn't find any help @ google or here.

The scenario: Windows Server 2008 Std x64 on i7-975, 12 GB RAM. The server is running in a data centre. One hardware NIC - RealTek PCIe GBE -> one MAC Address. The data centre provides us 4 static external IP's. The first is assigned to the host by default of course. I have ordered all 4 IP's, the data centre can assign the available IP's to the physical MAC address of the given NIC only. This means one NIC, one MAC Address, 4 IP's. Everything works fine so far.

Now, what I would like to have: Installed VirtualBox with 1-3 guests running, each gets it's own external IP assigned. Each of it should be an standalone Win Server 2008. It looks like the easiest way would be to put the guests into an virtual subnet and routing all data coming to the 2nd till 4th external IP through to this guests using there subnet IP's.

I have been through the VirtualBox User Manuel regarding networking.

What's not working: I can't use bridged networking without anything else, because the IP's are assigned to the one MAC address only. I can't use NAT networking because it does not allow access from outside or the host to the guest. I do not wanna use port forwarding. Host-only networking itself would not allow internet access, by sharing the default internet connection of the host, internet is granted from the guest to the outside but not from outside or the host to the guest. InternalNetworking is not really an option here.

What I have tried is to create an additional MS Loopback adapter for a routed subnet, where the Vbox guests are in, now the idea was to NAT the internet connection to the loopback 'subnet'. But I can't ping the gateway from the guests.

By using route command in the command shell or RRAS (static route, NAT) I didn't get there as well.

Solutions like the following do work for the one way, but not for the way back:

For your situation, it might be best to use the Host-Only adapter for ICS. Go to the preferences of VB itself and select network. There you can change the configuration for the interface. Set the IP address to 192.168.0.1, netmask 255.255.255.0. Disable the DHCP server if it isn't already and that's it. Now the Guest should get an IP from Windows itself and be able to get onto the internet, while you can also access the Host.

Slowly I'm pretty stucked with this topic. There is a possibility I've just overlooked something or just didn't getting it by trying, especially using RRAS, but it's kinda hard to find useful howto's or something in the web.

Thanks in advance!

Best regards, Simon