Re: setting bridge for VMs IP assignment by router's DHCP server

On 8/2/24 11:44 AM, Germano Massullo wrote: This method doesn't provide at all what you want - it will give you a bridge device that isn't directly connected to any physical interface, so any traffic between the guests connected to the bridge and the physical network must be *routed* vi the host's IP stack, i.e. it is on a different segment from the physical network and so no broadcast traffic will pass between the bridge and the physical network. This means that the bridge device must have a separate subnet, while you've given it no network at all. Basically the only thing such a network would be useful for would be to connect multiple guests that have statically configured IP addresses (on the same subnet) but isolate them from the outside network *and* the host itself (the host could still monitor traffic on the bridge, but none of that traffic would be sent up to the host IP stack for routing or forwarding - that would only be done if the bridge device was given an IP address (on the same subnet as the guests). Since you've used nmtui to create the bridge device, I'm guessing that it must be a standard Linux host bridge, and *not* an openvswitch bridge (OVS has its own commandline tools to create an OVS bridge. That being the case, you do *not* want the "<virtualport type='openvswitch'/>" element in your network config. Aside from that, when you create the bridge device, you need to make sure that you host ethernet is attached to the bridge, and that any IP configuration that was previously on the ethernet device is now on the bridge. (you'll be able to verify this by running "ip link show dev $name" for the ethernet and bridge devices, the ethernet device should say "master virbr1_no_nat" and have no IP addresses associated with it, and the bridge device should have the IP address that was previously (before you created the bridge) assigned to the ethernet. Once you've done both of these things, do a "virsh net-destroy br1_no_nat; virsh net-start br1_no_nat" and you should be able to start up your guest and have it connected directly to the physical network. (BTW, I would call the bridge device some shorter name BTW, most people just call it "br0" - not only is it easier to type, but the maximum length of a network device name is IFNAMSIZ-1 == 15, and you could easily run into some program that used IFNAMSIZ for the length of a buffer used to store some variation of the if name that was a few characters longer, and your name is already just 2 shy of the limit!)