What is a firewall | 5 Types of firewall in computer network

A firewall is a system designed to prevent unauthorized access from entering a private network by filtering information coming from the Internet. The firewall prevents unwanted traffic and permits traffic.


The purpose of a firewall is therefore to create a security barrier between a private network and the public Internet. Because on the Internet, there are always hackers and malicious traffic that can try to penetrate a private network to cause harm. And to prevent this, a firewall is the main component of a computer network.

And a firewall is especially important for a large organization that has a lot of computers and servers. Because you do not want to have access to all the devices on the Internet where a hacker can come into that organization and disrupt it. So you need a firewall to protect them.

A firewall that is used in a computer network is very similar to how a firewall works in a building structure. A firewall provides a barrier in the structure of a building so that an actual fire incident occurs, on either side of a building, to keep the firewall contained and to prevent it from spreading to the other side.

So the fire is the firewall to keep the entire building from destroying. And a network firewall works similar to a structure firewall. It prevents harmful activity before it spreads to the other side of the firewall and damages a private network.

In today’s high-tech world, every home and especially a business or an organization needs a firewall to keep its network secure. A firewall works by filtering incoming network data and determines by its rules that if it is allowed to enter a network, these rules are also known as access control lists.

Those rules are customizable and are determined by the network administrator. The administrator not only decides what can be entered into a network but can also leave a network. These rules either allow or deny permission.

Firewall can be rule-based

  • IP address Field name
  • The protocol
  • The programs
  • Ports
  • Keyword

Types of firewalls Host-based firewall – This is a type of firewall that is installed on a computer and it protects only one computer and nothing else.

Zone Alarm is one popular 3rd party host-based firewall. Many antivirus programs come with host-based firewalls. Network-based firewall network-based firewall is a combination of hardware and software and works at the network layer.

It is placed between a private network and the public Internet, but unlike a host-based firewall, where it protects only that computer, a network-based firewall protects the entire network, and this is done through management rules.

Those are applied to the entire network to prevent any harmful activity before accessing the computer. Network-based firewalls can be a stand-alone product used primarily by a large organization. They can also be built as computers or routers that depend on many small organizations.

Or they can also be deployed in the cloud infrastructure of the service provider. A lot about organizations will use both network-based and host-based firewalls. They will use a network-based firewall to defend the entire network.

And they will also use a host-based firewall to protect their computers and servers. And doing so will ensure maximum security. Because of the harmful data that happened just to get to the network firewall. Each computer will have host-based firewalls to prevent this.

Types of firewall

Packet-filtering firewall

These firewalls operate at points where devices such as routers and switches work.

They don’t router packets, but instead compare each packet to a set of criteria, like

Packets that don’t fit the criteria are dropped and not forwarded to the internet network.

Circuit-level gateway.

These firewalls monitor TCP and other network protocol messages as they are set up and determine if the session being initiated is valid and they do not inspect the actual data if the remote system can be trusted.

Stateful inspection firewall

These firewalls examine each data packet but they also monitor whether the packet is part of an established network session.

The provides more security than packet filtering or circuit monitoring but tacks a greater toll on network performance.

Application-level gateway

This firewall filters packets according to their intended service, as well as other attributes such as HTTP request strings. They are considered safe but also tax network performance.

Next-generation firewall

A typical next-generation firewall combines

  • Packet inspection
  • Stateful inspection
  • Deep packet inspection

And other security features like

  • Intrusion detection and prevention
  • Malware filtering
  • Antivirus

Choosing the best firewall beings with not only understanding the different types of firewalls but also understanding the architecture and functions of your network.

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