FirewallD - Opening a Port

Use this command to find your active zone(s):

firewall-cmd --get-active-zones

It will say either public, dmz, or something else. You should only apply to the zones required.

In the case of dmz try:

firewall-cmd --zone=dmz --add-port=<port>/tcp --permanent

Otherwise, substitute dmz for your zone, for example, if your zone is public:

firewall-cmd --zone=public --add-port=<port>/tcp --permanent

Then remember to reload the firewall for changes to take effect.

firewall-cmd --reload