Docker and KVM on the same host and networking

  If you are trying to get Docker and KVM to work on the same host then you will find that the networking is a  bit icky.

You'll need to tell iptables to allow forwarding on your network interface. As I always to things using a bridge (makes it easier to change network card if needed), I use br0 in this example.

cat <<EOF | sudo tee /etc/systemd/system/restore-iptables-rules.service > /dev/null [Unit] Description = Apply iptables rules [Service] Type=oneshot ExecStart=/bin/sh -c 'iptables -A FORWARD -i br0 -o br0 -j ACCEPT' [Install] WantedBy=network-online.target EOF  

Then you need to enable it and restart the service (I'd restart the host):

sudo systemctl daemon-reload \ && sudo systemctl enable restore-iptables-rules.service \ && sudo systemctl start restore-iptables-rules.service  

That should be it, now your KVM guests will be able to reach the network.

(there, of cause will be other things like enabling of forwarding which is also required).