1.任意运行一条iptables防火墙规则配置命令：
iptables -P OUTPUT ACCEPT
2.对iptables服务进行保存：
service iptables save
如果上述命令执行失败报出：The service command supports only basic LSB actions (start, stop, restart, try-restart, reload, force-reload, status). For other actions, please try to use systemctl.
解决方法：
systemctl stop firewalld 关闭防火墙
yum install iptables-services 安装或更新服务
再使用systemctl enable iptables 启动iptables
最后 systemctl start iptables 打开iptables
再执行service iptables save
3.重启iptables服务：
service iptables restart
执行完毕之后/etc/syscofig/iptables文件就有了
代码：
systemctl stop firewalld yum -y install iptables-services systemctl enable iptables systemctl start iptables service iptables save service iptables restart