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Re: [Xen-devel] nat does not work with hvm

To: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-devel] nat does not work with hvm
From: Erdem Bayer <ebayer@xxxxxxxxxxxx>
Date: Tue, 17 Apr 2007 14:32:54 +0300
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I have been playing with the xen-unstable and observed that the vif-nat script is still running in the case of nat in qemu (although on the wrong interface as you have explained) Did I miss something or is it still running in the unstable vers. because it will have support on one of the next releases. Will nat be supported in qemu by xen in future versions or should I write my own qemu-ifup script? Also I was thinking if it is possible to have more than one qemu-ifup scripts and activate them from the config. Is this possible?

For the qemu-ifup script the steps I think is as follows:

1. Determine ip information.
2. Bring interface tap up with the ip
3. write iptables rules to route packages to the domU through tap interface ip

So the problem is passing the necessary values to qemu-ifup scripts. I wonder where qemu-ifup script is called. Is it possible to change its parameters?

Am I right? Do you have anything to add? If you can guide me through this I am sure I can come up with a reasonable script.

Thanks for help

Keir Fraser wrote On 14-04-2007 13:19:
On 14/4/07 08:12, "Erdem Bayer" <ebayer@xxxxxxxxxxxx> wrote:

Will the vif-nat script be run for the hvm domain? If not how does the
vifX.0 interface and route rules in my first config be created? I think
the the answer of this question is yes. Then what will the qemu-ifup
script do? What I wonder is what is the purpose of the qemu-ifup script
if the vif-nat script will be run also?

Vif-nat isn't run in this case.

Well actually it is run in 3.0.4 (but not in the very latest xen-unstable
repository, so not in the forthcoming Xen 3.0.5). But it'll get run on the
wrong interface. The vif2.0, or whatever, interfaces aren't used by qemu.
qemu creates its own tap interface and the qemu-ifup script is executed to
configure that tap interface.

 -- Keir

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