I have some questions regarding the way that networking is handled via qemu/kvm+libvirt, namely I'm trying to replicate OpenStack's use of the magic IP on newly spun-up instances. My apologies in advance if this is not the proper mailing list for such a question. I've already been to the libvirt mailing list, but to no avail.

I am trying to determine how exactly I can manipulate traffic from a _guest's_ NIC using iptables on the _host_. On the host, there is a bridged virtual NIC that corresponds to the guest's NIC. That interface does not have an IP setup on it on the host, however within the vm itself the IP is configured and everything works as expected. I was told on the libvirt list that nwfilter handles things like this, but after further discussion was able to determine that nwfilter does NOT handle a situation in which one would redirect traffic destined for one IP to another IP -- a situation that iptables would normally handle.

I'm wondering, in that case, how OpenStack is (seemingly) "magically" making this happen? Because libvirt (via nwfilter) handles outbound traffic produced by a guest system (and thus, that traffic does not traverse iptables) that there would be no way to facilitate this...but as we all know, OpenStack does it :)

Any insight or pointing in the right direction would be so helpful, thanks in advance!


--
Andre Goree
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Email     - andre at drenet.net
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