CentOS Linux 7.2.1511, Webmin 1.791, Authentic Theme 17.72,
Strangely Virtualmin version is not show and hard to find. Latest version as of today 28/03/16
All seems good, but if you press the ‘Activate at Boot’ in webmin -> Networking -> Linux Firewall All rules are deleted.
To recover you must ‘Reset Firewall’ making sure to tick ‘Activate at Boot’ and make your rules again.
Currently, if you press the ‘Activate at Boot’ button it will never activate at boot again until you reset the firewall and make your rules again.