[libvirt] how do I stop libvirt futzing with my network configuration?
Daniel P. Berrange
berrange at redhat.com
Thu Nov 26 18:42:24 UTC 2009
On Thu, Nov 26, 2009 at 06:25:07PM +0000, Nix wrote:
> I thought it was easy to teach libvirt about this:
> spindle:/etc/libvirt/qemu/networks# cat /etc/libvirt/qemu/networks/default.xml
> <forward mode='route'/>
> <bridge name='vm-net' stp='on' delay='0' />
> <ip address='192.168.20.1' netmask='255.255.255.0'>
> <range start='192.168.20.1' end='192.168.20.254' />
> However, there appears to be no way to say 'this is what the network is
> already like'. That network is considered 'inactive' and can't be used by
> any guests, and if I try to make it active, I get this:
> virsh # net-start default
> error: Failed to start network default
> error: cannot create bridge 'vm-net': File exists
> Of course it bloody can't create that bridge: it's already there, has an
> IP address on the host, and has the host routing packets to it. There
> appears to be no option to allow libvirt to assign IPs on the host...
> ... should I fix that, 'net-start' tries to update iptables rules!
> How should I put this: I do not *not not* want libvirt pissing with the
> firewall in any way at all. If I want firewall rules, I'll create them.
> But there's no way to tell it 'hands off! This network is already active,
> don't try to *make* it active!'
If you don't want libvirt to create the bridge + setup IPtables rules
then don't use the net-XXX commands / XML. That functionality is
not there for pointing libvirt to existing bridge devices.
If you already have a bridge configured, then just point the guest
directly at that bridge by name.
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