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This question has alread been posted on stackoverflow ( but since I recognized that it might be offtopic there, I'll repeat it here:

I'll explain the current situation first and then I'll describe my wishes:

Current Situation

At the moment I have one linux machine with three public IP-Adresses configured on one physical interface. The machine can be reached via each of these IPs.


In the future I want to use virtualization on this machine and assign one of these three IPs to a specific virtual machine. But for some reasons I cannot use bridging for the physical interface and the virtual interface. Using NAT and/or PAT is also not possible.

The Problem

My idea was to configure the virtualization host as router and set up a route for this specific public IP via the virtual network interface (with private addresses).

Is this possible at all? Did I overlook something? Or are there other solutions for my problem?

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You should use bridging. If something prevents you from doing so, fix it. – Michael Hampton Feb 15 '13 at 23:19
The reason that prevents me from doing so is something that I cannot change - it's some configuration on the ISP side - using bridging will lead to disconnection caused by security settings. – mschenk74 Feb 15 '13 at 23:26
Sounds like Hetzner. – Michael Hampton Feb 15 '13 at 23:37
There's a reason actual routers/firewalls exist. This is one of them. – TheCleaner Feb 15 '13 at 23:43
up vote 1 down vote accepted

Yeah, AFAIR, you can do that kind of stuff with Linux networking stack, but remember — you'd need proxy arp for the external interface to be turned on (and aliased IP-address to be removed from it — more than likely, but I'm not 100 %-sure, should/could be easily verified).

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