Different Types of Firewalls and How They Work?

The most common challenge many professionals face is finding the right tool to secure their data. There are many different types of firewalls, and they don’t have a clearer idea as to which type of firewall is considered the most secure.

The firewalls are central in securing the corporate network, data, and other resources. It is essential to know about them so you can secure your sensitive data in the best possible way.

Read this article to know what a firewall is in networking, its types, and which one to choose.

What Are the Different Types of Firewalls?

Before moving to the types of firewall, it is important to know what a firewall is and how it works.

What is a Firewall in Networking?

A firewall is a cybersecurity tool that filters network traffic. It allows legitimate traffic to pass and blocks malicious requests.

This way, you can control your network traffic flow by implementing a firewall software or a device.

Do Read Authentication vs. Authorization

Why is Firewall Important?

It is important as it protects your network and shields it against attacks and other malicious activities. Furthermore, it also prevents harmful or malicious software from entering into your device or the network via the internet.

Also Read DOS vs DDOS Attack

How Does a Firewall Work?

When you install a firewall on your computer, it monitors everything that goes in and out of it. A firewall makes use of the following methods to secure your network and control the traffic flow.

a) Packet Filtering

It creates filters by using predetermined security rules. If the filter flags a packet, then that packet is not allowed to pass.

b) Proxy Service

Proxy is an intermediary application between the systems.

The proxy servers are found on the firewall application layer. This is where the sessions are conducted between both the connections. Their role is to centralize the information transfer for a firewall scan.

c) Stateful Inspection

The details for both the connections are stored in a database. The firewall then compares the information, and if it’s correct, then it allows the information to pass through; otherwise, it blocks it.

Types of Network Firewalls

The different types of firewall popular among the professionals and used in large enterprises are:

1) Hardware Firewall

Larger enterprises make use of the hardware firewall to protect the internal network. It is also used as a border device. There are various physical interfaces of the hardware firewall. Some popular brands that manufacture such a type are Cisco, SonicWall, Juniper, etc.

2) Software Firewall

The software firewall comes as a stand-alone application while the hardware firewall is installed on the network devices.

The windows firewall that comes installed by default in windows OS is an example of the software firewall.

3) Packet Filtering Firewall

It is installed on the device connecting the internal network to the internet, i.e., the router. This type of firewall can be deployed on the network layer only.

It makes use of the Access control Lists rules and works according to it. Furthermore, it checks each and every packet, and if the packet isn’t according to the rules defined, then it drops it.

It is found on the three and 4th layer of the OSI model. The packet filtering firewall is best for smaller networks as it consumes fewer resources.

The packet filtering is also termed the stateless firewall.

4) Stateful Multilayer Inspection Firewall

This one is a combination of different firewalls. It allows only those packets to pass through that match to an active connection.

There is a table of current sessions termed as the stateful database.

The stateful multilayer inspection firewall makes use of ACLs to do packet filtering at the network layer.

It saves the important details such as the port, IP of the source and destination, and the TCP flags. It then checks the valid sessions on the basis of the details stored.

Furthermore, it also checks the packets on the application layer. It implements the security models to make the connection more secure.

It is important to know the stateful vs. stateless firewall difference too.

5) Application Firewall

This one does packet inspection at the application level. There is a specialized software that acts as an intermediary between the source and the destination.

It differentiates the malicious traffic from the normal traffic of the application. Moreover, it works according to the protocols configured.

Some examples include the web application firewalls and the proxy firewall.

6) Circuit Level Gateway Firewalls

It works at the session layer and finds the legitimate sessions by monitoring the TCP handshaking. The firewall offers the UDP and TCP security. Here the screening is done before the connection is made.

It is a virtual circuit between the internal client and the proxy server. This firewall isn’t present on the machines and, in fact, is present on the individual server or client within the network.

Have a Look at SSH vs SSL Difference

7) Next-Generation Firewall (NGFW)

It comes with some advanced features and offers security from the known malware attacks and other threats. This firewall comes from the third generation.

It improves network traffic filtering and adds more OSI model layers. The firewall performs a thorough inspection style and goes deeper. The administrators who use it get more control over the application and deeper inspections.

8) Personal Firewall

This is referred to as the desktop firewall. By installing it, the PC users mark themselves safe from the intruders’ attacks.

It offers great security to the users who connect to the internet by a cable modem or a DSL connection. The firewall controls the internet connection and performs inbound and outbound filtering.

9) Transparent Firewall

This is a layer two firewall that works on the bridged packets. Here the MAC lookup is done.

Also Read What is Network Segmentation?

Final Words

Firewall offers impressive security to the networks, users, and devices by controlling the traffic between two points. They inspect the network frame and apply the rules.

Then based on these rules, they make certain decisions. There are different types of firewall, and each of them has its own characteristic that enhances the security of your system and network.

Also Checkout IDS vs. IPS: What’s the Difference?