CentOS 7 reports that the iptables firewall prompts "Unit iptables. service failed to load"

I have been using CentOS 6 for a while, but I am not used to it. After the firewall is configured, run service iptables save to display "Failed to restart iptables. service: Unit iptables. service failed to load: No such file or directory. "Error. In CentOS 7, RHEL 7, or Fedora, the firewall is managed by firewalld. Of course, you can restore the traditional management method. Or use the new command for management.

If you use traditional commands, run the following command:

Systemctl stop firewalld
Systemctl mask firewalld
 

And install iptables-services:

Yum install iptables-services
Set boot start:

Systemctl enable iptables

Systemctl [stop | start | restart] iptables
# Or
Service iptables [stop | start | restart]
 

Service iptables save
# Or
/Usr/libexec/iptables. init save

From the above solution, the firewall is not started, and the iptables firewall service is not started.