Firewall Definition

The firewall definition is a network security component that is designed to safeguard computer networks from unauthorized access. The purpose of implementing this safeguard in a computer network is to create a safety barrier between the private network and the public Internet.

A firewall blocks unauthorized access and unwanted Internet traffic by filtering the information that comes through the Internet and permitting only the desired traffic into the private network. It protects your network from hackers & malicious traffic that may try to penetrate your private network to cause harm such as spreading computer viruses and stealing your data.

There are two types of firewalls. First is the host-based which is a software that can be installed on a computer to protect only that computer from unauthorized access. The second type is network-based which consists of hardware and software and operates at the network layer. It is placed between the private network and the public Internet to protect the entire network from unauthorized access.

How does a Firewall work?

Now that you know the firewall definition, let’s see how it works. It starts by filtering the incoming and outgoing network data based on a predefined set of rules which is called an access control list.

The access control list is customizable and the network administrator decides access through which sources are allowed to pass through the firewall.

The network administrator can add rules in the access control list to control access by the IP address, the port number, destination, etc.

When there is incoming traffic, the firewall looks upon the access control list and checks if the port number or the IP address of the source is allowed to access the network.

Based on the given rules, the firewall either grants permission to pass through the firewall or denies access to the network.