A Linux firewall used to protect your workstation or server from unwanted traffic. You can set up rules to either block traffic or allow through. RHEL 8 comes with a dynamic, customizable host-based firewall with a D-Bus interface. You can add or delete or update firewall rules without restarting the firewall daemon or service. firewall-cmd act as a frontend for the nftables.
In RHEL 8 nftables replaces iptables as the default Linux network packet filtering framework. This page shows how to set up a firewall for your RHEL 8 and manage with the help of firewall-cmd (firewalld frontend) admin tool.