Check the status of the firewall:
systemctl status firewalld
sees active (running) indicating that it has been turned on
Start the firewall:
systemctl start firewalld
View all open ports in the firewall:
firewall-cmd --zone=public --list-ports
Open port, for example, I want to open port 8888:
firewall-cmd --zone=public --add-port=8888/tcp --permanent
If you need to close this port:
firewall-cmd --zone=public --remove-port=8888/tcp --permanent
Restart the firewall to make the configuration take effect:
firewall-cmd --reload
Turn off the firewall:
systemctl stop firewalld
Set boot firewall:
systemctl disable firewalld