The Beginner's Guide to iptables, the Linux Firewall | ITechBrand.com

Here we can see, "The Beginner's Guide to iptables, the Linux Firewall"

A firewall may be a system that gives network security by filtering incoming and outgoing network traffic supported by a group of user-defined rules. Generally, a firewall aims to scale back or eliminate unwanted network communications while allowing all legitimate communication to flow freely. In most server infrastructures, firewalls provide an important layer of security that, combined with other measures, prevent attackers from accessing your servers in malicious ways.