FirewallD

FirewallD is an IPv6 compatible firewall mechanism used in recent Linux distributions (RedHat/Fedora/CentOS) replacing good old iptables.

dynamically managed firewall;
support for network/firewall zones (define trust level of network connections/interfaces;
support both IPv4 and IPv6;
support ethernet bridges and IP sets;
separated runtime/permanent configuration;
service/application can add firewall rules directly;

FirewallD not running...

If Firewalld is not running you have to start it manually i.e, from commandline:

sudo systemctl start firewalld

FirewallD with some basic rules

Firewalld should open port 10000 for webmin:

firewall-cmd --permanent --zone=public --add-port=10000/tcp

reload is needed to activate the permanent rule in current environment

firewall-cmd --reload

If you managed to stop firewalld restart with:

systemctl start firewalld

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