I love Webmin - it makes admin'ing my VPS so easy. But I have had trouble using the Linux Firewall page. I wonder if Webmin is not compatible with iptables-persistent. There are several problems:
After installing (with apt install iptables-persistent) the Linux Firewall page shows that the iptables files are saved in /etc/iptables.up.rules and /etc/ip6tables.up.rules This is not correct - they're saved in /etc/iptables/rules.v4 and /etc/iptables/rules.v6.
The Activate at boot control doesn't work. a) If I click Yes, then click Activate at boot, then reboot the system, the "No" button is checked again. b) The iptables rules are not reloaded - I get a default set of rules.
The list of rules displayed does not match the active set (from /etc/iptables/rules.v4 and /etc/iptables/rules.v6). It may be the leftover rules from /etc/iptables.up.rules and /etc/ip6tables.up.rules
The help text (top of the page, second button from the left) speaks of "ipi(6)tables" - I suspect this should be "ip(6)tables"...
How can I make the Webmin page reflect the actual state of my iptables? Many thanks.
PS I also want to say something nice: Since I have chosen not to use firewalld, I removed it with sudo apt purge firewalld. Webmin DOES give a good diagnostic message if I click FirewallD (It says, "The FirewallD module cannot be used : The FirewallD control command firewall-cmd was not found on your system")