Firewall CMD Basics

List all rules

sudo firewall-cmd --list-all

Check state

sudo firewall-cmd --state

Add permanent rule

sudo firewall-cmd --permanent --zone=public --add-service=http 
sudo firewall-cmd --permanent --zone=public --add-service=https
sudo firewall-cmd --reload

View the default zone

Zones are pre-constructed rulesets for various trust levels

sudo firewall-cmd --get-default-zone

List all zones

sudo firewall-cmd --list-all-zones

View all services

sudo firewall-cmd --get-services

Add a nonstandard port:

sudo firewall-cmd --zone=public --add-port=3030/tcp --permanent
sudo firewall-cmd --reload

Sources