centos7执行命令iptables 出现Unit iptables.service failed to load: No such file or directory.

解决方式：安装iptables-services

yum install iptables-services

开机启动：

systemctl enable iptables

systemctl stop iptables
systemctl start iptables
systemctl restart iptables
systemctl reload iptables

保存设置：
service iptables save