[Novalug] nat bridge for kvm (centos 5.4)

Sean Spurrier sean.spurrier@gmail.com
Fri Oct 23 17:13:35 EDT 2009


Forgot one part ...sysconfig file below

DEVICE=br0
TYPE=Bridge
BOOTPROTO=dhcp
ONBOOT=no

(and because I don't always use the bridge I have the brctl commands in an
init script I can fire off when I need it)

YBMV
Sean

On Fri, Oct 23, 2009 at 5:05 PM, Sean Spurrier <sean.spurrier@gmail.com>wrote:

> John,
>
>   Shooting this off the top of my head because my rhel5.4 box is rebuilding
> as we speak,  You can do all of this by editing sysconfig scripts or you can
> use the utility I cover below ( I am not sure of the default behaviour of
> virbr0 but you might be able to modify it to do the same)
>
> you should be able to use a command called brctl (part of bridge-utils
> package) to show you existing bridges and if they are tied to a physical
> interface.
> >brctl show
>
>  What I do on my hosts is create a bridge (I call mine br0) and add one of
> my physical nics to it (eth0 )
> >brctl addbr bro
> >brctl addif eth0
>
> Now to have libvirt pickup the bridge restart libvirt
> >service libvirt restart
>
> So now you have a bridge which can be assigned to a virt either using
> virt-manager
> So if you are running DHCP on the network eth0 is attached to a virt
> assigned to use br0 will pull its address/dns from there and you can now ssh
> into it from another box (better then having a local NAT on the box, and
> keeps your iptables rules cleaner)
>
> if you edit your virtual machine config files directly just edit
> /etc/libvirt/qemu/<insertguestnamehere>
> look for a section that starts with <interface type='bridge' > and you will
> want to put the name of your bridge on the line that says
>
>
> <source bridge='br0'/>
>
> and that should do it for you.
>
>
>
>
>
>
>
> On Fri, Oct 23, 2009 at 7:48 AM, John Holland <jbholland@gmail.com> wrote:
>
>> OK, I just upgrade my CentOS to 5.4 and created a KVM. the vm (happens to
>> be freebsd) can access the virbr0 interface on the CentOS from which it can
>> to DNS lookups. but it can't reach the outside world. Anyone know what I
>> need to do to fix that?
>>
>> John
>>
>> --
>>
>> ______________________________________
>>
>> Note new email address jbholland@gmail.com
>>
>> _______________________________________________
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>>
>>
>
>
> --
> Sean R. Spurrier
>
>


-- 
Sean R. Spurrier
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