13.3 Configuring Firewall Rules with firewall-cmd

The firewall-cmd command-line utility allows information about the firewalld configuration to be viewed and changes to be made to zones and rules from within a terminal window.

When making changes to the firewall settings, it is important to be aware of the concepts of runtime and permanent configurations. By default, any rule changes are considered to be runtime configuration changes. This means that while the changes will take effect immediately, they will be lost next time the system restarts or the firewalld service reloads, for example by issuing the following command:

# firewall-cmd --reload

To make a change permanent, the --permanent command-line option must be used. Permanent changes do not take effect until the firewalld service reloads but will remain in place until manually changed.

13.3.1 Identifying and Changing the Default Zone

To identify the default zone (in other words the zone to which all interfaces...