DHCP not working in VM connected to host bridge

Hello,

Since the upgrade to Fedora 32, my VMs connected to a bridge are not getting IP by DHCP. Sniffing with tcpdump, I see the requests in the host bridge, but nothing reaches the external switch.

Any idea of what could be happening? This has been working for years. I’m suspecting in firewalld + nftables, but I haven’t seen anything wrong.

HOST:

#  tcpdump  -ei br-dmz udp and \( port 67 or port 68 \)
dropped privs to tcpdump
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on br-dmz, link-type EN10MB (Ethernet), capture size 262144 bytes
19:03:47.646411 52:54:00:48:97:48 (oui Unknown) > Broadcast, ethertype IPv4 (0x0800), length 333: 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 52:54:00:48:97:48 (oui Unknown), length 291
19:03:48.630150 52:54:00:48:97:48 (oui Unknown) > Broadcast, ethertype IPv4 (0x0800), length 333: 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 52:54:00:48:97:48 (oui Unknown), length 291
19:03:50.630130 52:54:00:48:97:48 (oui Unknown) > Broadcast, ethertype IPv4 (0x0800), length 333: 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 52:54:00:48:97:48 (oui Unknown), length 291
19:03:52.636080 52:54:00:48:97:48 (oui Unknown) > Broadcast, ethertype IPv4 (0x0800), length 333: 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 52:54:00:48:97:48 (oui Unknown), length 291

# brctl show br-dmz
bridge name	bridge id		STP enabled	interfaces
br-dmz		8000.9e613049e82a	yes		enp5s0.5
							vnet0
# ip address show dev br-dmz
5: br-dmz: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 9e:61:30:49:e8:2a brd ff:ff:ff:ff:ff:ff

It seems that you are not alone: Bug 1832723 - Libvirt VMs running on Bridged Network don’t get IPv4 DHCP, only IPv6

Thanks, that’s it. Removing the br_netfilter module fixes the issue.

# rmmod br_netfilter
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