1:查看防火状态
    systemctl status firewalld
    service iptables status
    2:暂时关闭防火墙
    systemctl stop firewalld
    service iptables stop
    3:永久关闭防火墙
    systemctl disable firewalld
    chkconfig iptables off
    4:重启防火墙
    systemctl enable firewalld
    service iptables restart
    5:永久关闭后重启（未测试）
    chkconfig iptables on