sudo systemctl status qubes-iptables
sudo systemctl status qubes-firewall
/lib/systemd/system/qubes-firewall.serviceruns/usr/bin/qubes-firewall/usr/lib/python3/dist-packages/qubesagent/firewall.py/lib/systemd/system/qubes-iptables.service→/usr/lib/qubes/init/qubes-iptables
Would be most useful if this information was in a wiki or at least website so it can be collaboratively edited to expand, improve, complete, etc.