centos7 默认不用iptables而是用firewall
systemctl start firewalld.service#启动firewall systemctl stop firewalld.service#停止firewall systemctl disable firewalld.service#禁止firewall开机启动
firewall-cmd --state --查看firewall 当前状态
firewall 具体用法 参考http://www.centoscn.com/CentOS/Intermediate/2015/0313/4879.html
