启动防火墙
systemctl start firewalld
关闭防火墙
systemctl stop firewalld
重启防火墙
systemctl restart firewalld
查看防火墙状态
systemctl status firewalld
重新加载防火墙
firewall-cmd –reload
查看开放的端口
firewall-cmd –list-ports
添加端口
firewall-cmd –add-port=3306/tcp –permanent (参数permanent表示永久生效，重启后也不会失效)
关闭端口
firewall-cmd –remove-port=3306/tcp –permanent
开机启用
systemctl enable firewalld
开机禁用
systemctl disable firewalld
查看监听的端口
netstat -lntp
查看端口是否被占用
netstat -lntp | grep 8000（端口号）