Open Port Permanently with firewalld in linux

linux, networking

First thing to do after installing a service that listening on your network interface is to test in your preferred internet browser.

However, if your firewalld is running, you will be getting a connection error message and this is how you should open it. Permanently.

# firewall-cmd --permanent --zone=public --add-port=<portNo>/tcp
# firewall-cmd --reload
# firewall-cmd --list-all

Explanation

Configure the new rule to be implemented permanently, --permanent
The rule is in specific zone, with specific port number and protocol, firewall-cmd --permanent --zone=public --add-port=/tcp
To reload firewall-cmd with new rule, --reload
Listing all rule in, --list-all

Note: Removing --permanent will caused it to take effect immediately, but the configuration is volatile!