CentOS virt - Feb 2014 - MS-Win7 kvm guest gets dhcp from host bridge

CentOS-6.5
i86_64
qemu-kvm-0.12.1.2-2.415.el6_5.4
MS-Windows v7proSP1

We have installed a MicroSoft Win7 system as a guest and have joined it to our
MS AD domain. The system runs and has internet access.  However, the IPv4
address it obtains and the gateway it is assigned are both sourced from the
virtual machine host system and not from our AD DC DHCP server.

To clarify, the virbr0 IP address is 192.168.122.1 and the Windows guest has
that address as its gateway and an IP address in the 192.168.122.0/24
netblock.  This is not as we desire as the internal addresses we regularly
assign to MS workstations via DHCP are supposed to belong to a different
netblock entirely.  This permit filtering on incoming and outgoing traffic at
the gateway.

I realize that there is a DHCP service running on virbr0 for the purpose of
provisioning guests with system control traffic but I do not know how to limit
that to its intended purpose and allow another DHCP server to provide the IP
address to the windows guests.  I hope that problem description is not too
confusing.

Can anyone provide me with some guidance on the matter?  Are kvm guests
required to have either static ip addresses or dhcp addresses provided by the
host system?

Thanks in advance.

-- 
***          E-Mail is NOT a SECURE channel          ***
James B. Byrne                mailto:ByrneJB at Harte-Lyne.ca
Harte & Lyne Limited          http://www.harte-lyne.ca
9 Brockley Drive              vox: +1 905 561 1241
Hamilton, Ontario             fax: +1 905 561 0757
Canada  L8E 3C3

On 02/19/2014 04:01 PM, James B. Byrne wrote:
> CentOS-6.5
> i86_64
> qemu-kvm-0.12.1.2-2.415.el6_5.4
> MS-Windows v7proSP1
>
> We have installed a MicroSoft Win7 system as a guest and have joined it to
our
> MS AD domain. The system runs and has internet access.  However, the IPv4
> address it obtains and the gateway it is assigned are both sourced from the
> virtual machine host system and not from our AD DC DHCP server.
>
> To clarify, the virbr0 IP address is 192.168.122.1 and the Windows guest
has
> that address as its gateway and an IP address in the 192.168.122.0/24
> netblock.  This is not as we desire as the internal addresses we regularly
> assign to MS workstations via DHCP are supposed to belong to a different
> netblock entirely.  This permit filtering on incoming and outgoing traffic
at
> the gateway.
>
> I realize that there is a DHCP service running on virbr0 for the purpose of
> provisioning guests with system control traffic but I do not know how to
limit
> that to its intended purpose and allow another DHCP server to provide the
IP
> address to the windows guests.  I hope that problem description is not too
> confusing.
>
> Can anyone provide me with some guidance on the matter?  Are kvm guests
> required to have either static ip addresses or dhcp addresses provided by
the
> host system?
It sounds like what you need to do is create a bridge and then connect 
your virtual machine to the bridge so that it can receive DHCP from the 
external network.  I assume you are using libvirt. If so, check out the 
page below. It may help you get started in the right direction.

http://wiki.libvirt.org/page/Networking#Bridged_networking_.28aka_.22shared_physical_device.22.29

Dusty