Linux allows opening through firewall ports

1. firewall-cmd --zone = public --add-port = 4400-4600 / udp --permanen (specified port range is 4400-4600 through firewall) Warning: ALREADY_ENABLED: 3306: tcp (indicating that port 3306 passed successfully)
2. firewall-cmd --zone = public --remove-port = 80 / tcp --permanent (close the specified port)
3. firewall-cmd --zone = public --list-ports (view the ports passed)