If you want to work with Firewall-D,
there's a couple of components that you need to know about.
So first component, and probably the most important one
for your RHCSA, is the service.
Not to be confused with services in Systemd.
So this is the main component.
It's really an XML file that contains one or more ports,
as well as optional kernel modules,
if these are involved, that should be loaded.
Then there is the zone.
The zone is the default configuration
to which network cards can be assigned
to apply specific settings, not needed for RHCSA.
Ports are optional elements to allow access to specific ports.
But if you are going to do ports,
you might as well create a service
so that you can run everything in a consistent way.
Additional components are available as well,
but they are not frequently used in a base firewall
configuration.
In the next video, you'll show how
to use these most relevant components.