执行命令
systemctl stop firewalld
systemctl mask firewalld
安装iptables-services
yum install iptables-services
设置开机启动
systemctl enable iptables
systemctl stop iptables
systemctl start iptables
systemctl restart iptables
systemctl reload iptables
保存设置
service iptables save
解决CentOS7关闭/开启防火墙出现Unit iptables.service failed to load: No such file or directory.
原文：https://www.cnblogs.com/xstCoding/p/15153556.html