centos6
service iptables stop 临时
chkconfig iptables off 永久
service iptables status
centos7
systemctl stop firewalld.service #停止firewall
systemctl disable firewalld.service #禁止firewall开机启动
firewall-cmd --state #查看默认防火墙状态（关闭后显示notrunning，开启后显示running）