How to Fix ???firewall-cmd: command not found??? Error in RHEL/CentOS 7

Tecmint: firewall-cmd is a command line front-end for firewalld (firewalld daemon), a dynamic firewall management tool with D-Bus interface.

It supports both IPv4 and IPv6; it also supports networks firewall zones, bridges and ipsets. It allows for timed firewall rules in zones, logs denied packets, automatically loads kernel modules, and so many other features.