https://meta.discourse.org/t/applying-docker-discourse-iptables-rules-when-using-csf-firewall/70531/5

csf v12.08

NOTE: This feature is currently in BETA testing, so may not work correctly

This section provides the configuration of iptables rules to allow Docker
containers to communicate through the host. If the generated rules do not
work with your setup you will have to use a /etc/csf/csfpost.sh file and add
your own iptables configuration instead

1 to enable, 0 to disable