解决Linux关闭或开启防火墙出现Unit iptables.service failed to load: No such file or directory.

报错：

Redirecting to /bin/systemctl stop iptables.service Failed to stop iptables.
或是
Failed to start iptables.service: Unit iptables.service failed to load: No such file or directory.

解决方法：

注意：以下操作均在root用户下进行！

1、执行以下命令：

systemctl stop firewalld
  
systemctl mask firewalld  

2、安装iptables-services：

yum install iptables-services  

3、设置开机启动：

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

4、保存设置：

service iptables save