You may already know that CentOS 7 use Firewalld as the front end interface to manage netfilter firewall and not Iptables.
So the purpose of this tutorial is to learn how to install and configure Iptables on CentOS 7 Linux, since many of the Linux system administrators still prefer Iptables over Firewalld. So do the following steps.
CentOS 7 Firewalld Allow us to block all incoming and outgoing network traffic using just one single command. This is Also called as panic mode. When the panic mode is on, all incoming and outgoing packets will be dropped and active connections will expire.