1, firewall 允许与禁用端口

firewall-cmd --zone=public --add-port=54212/tcp --permanent    //允许 TCP 端口 
firewall-cmd --zone=public --add-port=54212/udp --permanent  

firewall-cmd --zone=public --remove-port=5421/tcp --permanent   //禁止 
firewall-cmd --zone=public --remove-port=5421/tcp --permanent

firewall-cmd --reload

firewall-cmd --state    # 确认 firewalld 是否运
firewall-cmd --list-all  
firewall-cmd --get-active-zones
firewall-cmd --zone=public --list-all

检查防火墙系统

systemctl is-active firewalld
systemctl is-active nftables
systemctl is-active iptables

/etc/firewalld/firewalld.conf     //NftablesTableOwner=yes    配置项控制