[CentOS-virt] MS-Win7 kvm guest gets dhcp from host bridge

Mon Jun 23 16:44:26 UTC 2014
James B. Byrne <byrnejb at harte-lyne.ca>

On Mon, June 23, 2014 00:29, Arun Khan wrote:
> On Thu, Feb 20, 2014 at 3:36 AM, Dusty Mabe <dustymabe at gmail.com> wrote:
>> On 02/19/2014 04:01 PM, James B. Byrne wrote:

The root cause of the original problem was a change in the behaviour of
libvirt (and the GUI of virt-manager) when creating new vms.  The host system
was already bridged and had other vms previously created and attached to the
bridge without exhibiting this behaviour.  I infer that at some point an
update to libvirt altered the default configuration to always prefer NAT. A
change that I failed to notice and was not conscious of given I had previous
created vms without encountering this problem.  Changing the configuration of
the affected vms nic Source Device to 'Specify shared device name' and then
specifying the Bridge Name fixed the problem.

I have already commented elsewhere on the needlessly obtuse wording used for
the Source Device when bridging is required.  Why it does not say 'Specify
bridge name' or 'Use named bridge' instead has not been plausibly explained by
the maintainers.  It is particularly vexatious given that when one selects
'Specify shared device name' the GUI immediately alters to display a text box
labelled 'Bridge name:'  Duhhh.

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