Re: [libvirt] how do I stop libvirt futzing with my network configuration?
On Sat, Nov 28, 2009 at 5:06 PM, Nix <nix(a)esperi.org.uk> wrote:
On 28 Nov 2009, Ian Woodstock spake thusly:
> I've been running with this configuration for many months on dozens of hosts.
>
> - Created a bridge (the old fashion way) in /etc/sysconfig/network-scripts
> Bridge called br0 with one device eth1.
>
> - Created a VM in virt manager (or edit existing)
> Picked "Shared Physical Device" Device "eth1 (Bridge br0)" in
the GUI.
That's the mystery. I did it (directly via brctl, as it happens, 'cos I'm
making several with particular properties and want to enforce them):
spindle:/etc/libvirt/qemu# brctl show
bridge name bridge id STP enabled interfaces
linux-net 8000.06eb4e4985df no dummy0
[...]
52: linux-net: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state
UNKNOWN
link/ether 06:eb:4e:49:85:df brd ff:ff:ff:ff:ff:ff
inet 192.168.20.1/32 scope global linux-net
(hm, the state UNKNOWN is sort of bizarre. It's up...)
It's unknown because you're using the dummy device (which will just
send all bits to a deep dark hole) and we can't do things like check
the status of the interface/link etc.
I suspect that's why libvirt won't let you connect to it, since
libvirt is looking for a "shared physical device" and there's not a
device in the bridge.
(dummy0 is a member of this bridge because I've previously noted that a
bridge with no members at all isn't picked up by the GUI).
It appears in the GUI, all right: as 'host device linux-net (not bridged)',
greyed out and unselectable. Calling a bridge 'not bridged' is more than
slightly bizarre.
Actually I think this is correct. It's not bridged to a physical
device, it's plumbed to nothing.
Perhaps the netcf thing means I'm *required* to stick stuff in
/etc/sysconfig/network-scripts even though I'm not using RH so it would
never otherwise be used? From my reading of the source, that's not so...
No, it's not required, it just must be up some how (brctl works fine)
I suppose I should just have it check for the bridge and rip out all this
other stuff, but it seems bizarre that I have to do it.
> Or just add it to the VMs XML
That's too late to run the installer if it needs to access the network :/
I suppose I could continue doing the VM installation qemu run by hand...
> Works like a charm and there's certainly no configuration in libvirt
> for this interface, ie. nothing in /var/run/libvirt/network, and
> *nothing* set up in Virt Manager under "Host Details->Virtual networks
>
> You do need to make sure that you disable netfilter on the bridge or
> setup the appropriate iptables rules ( see
>
http://wiki.libvirt.org/page/Networking#Bridged_networking_.28aka_.22shar...)
There's no iptables at all on this particular box (at least not yet,
although it may turn up later on when I put Windows guests on here: I'm
not having *them* running around free).
So it sounds like the root of your issue now is that you're using
dummy network device.
Is that being done temporarily now because you don't have a network
plumbed in or is there some other use case?