Hi, I met a problem setting up virt-manager and libvirt: I want to use an existing customized network bridge with libvirt (I need special iptables rules and a custom DHCP setup). So I created a network definition file like this: <network> <name>NAT</name> <bridge name='br-nat' /> </network> Unfortunately, I'm unable to activate this network, because libvirt tries to create the bridge `br-nat' and fails, because it already exists: # virsh net-start NAT error: Failed to start network NAT error: cannot create bridge 'br-nat': File exists I just want libvirt to attach the guest's tap devices to this existing bridge. I don't want libvirt to manage the network. Is there any chance to realize this set-up? It should work with virt-manager using the graphical wizard.

Le lundi 19 octobre 2009 à 09:14 +0200, Chris Lalancette a écrit : > Sascha Frey wrote: >> Hi, >> >> I met a problem setting up virt-manager and libvirt: >> >> I want to use an existing customized network bridge with libvirt >> (I need special iptables rules and a custom DHCP setup). >> >> So I created a network definition file like this: >> <network> >> <name>NAT</name> >> <bridge name='br-nat' /> >> </network> >> >> Unfortunately, I'm unable to activate this network, because libvirt >> tries to create the bridge `br-nat' and fails, because it already >> exists: >> >> # virsh net-start NAT >> error: Failed to start network NAT >> error: cannot create bridge 'br-nat': File exists >> >> >> I just want libvirt to attach the guest's tap devices to this existing >> bridge. I don't want libvirt to manage the network. >> >> Is there any chance to realize this set-up? >> It should work with virt-manager using the graphical wizard. > > Yes, just don't define a new network. To use existing bridges, you just need to > edit your guest XML files to use something like: > > <interface type='bridge'> > <mac address='00:16:3e:4a:f6:89'/> > <source bridge='br0'/> > </interface> > > Note that configured bridges should also show up in virt-manager, I believe. Existing bridge shows up in virt-manager when run on the local machine. If you use a remote connection (at least qemu+ssh), you don't see it, you need to manually edit the guest XML. (btw, is this a known "problem" or a bug ?)