在centos7上安装iptables防火墙

规则配置: iptables -P OUTPUT ACCEPT

1.关闭原先CentOS7自带的firewall防火墙:
systemctl stop firewalld

2.安装或更新iptables服务
yum install iptables-services

3.启动iptables
systemctl enable iptables

4.打开iptables
systemctl start iptables

5.保存iptables
service iptables save

6.重启iptables服务
service iptables restart

来源：https://www.cnblogs.com/ayeex/p/12233233.html