Firewalls are network security devices that are used in almost every organization in 2023. Firewalls play an important role in network security. Along with technology growth, the number of cyber-attacks is also increased. Therefore, Network Security is important for every business. In this article, we will discuss different types of network firewalls based on their working behavior and features. Let’s get started!

Types of Network Firewalls

There are mainly five types of firewalls, i.e., Packet Filtering Firewalls, Stateful Inspection Firewalls, Circuit Level gateways, Application-level gateways, and Next Generation (NG) firewalls. We will discuss each of the network firewalls in detail.

1. Packet Filtering Firewalls

Packet Filtering Firewalls, as the name suggests filter a packet can be filtered based on source or destination IP address, protocols, and ports. It monitors each packet traversing from different interfaces. The firewall inspects each packet and after the inspection, a decision will be made according to the security policies configured on the firewall. But, everything will happen after the packet inspection.

This type of firewall doesn’t have information on the packet state. Therefore, it is also called Stateless Packet Filtering.

2. Stateful Inspection Firewalls

Stateful inspection firewalls maintain records of active connections. Thereafter, the firewall will use this information to allow or block an IP packet. Simply, if the firewall has packet stat in the database, then only it allows the packet otherwise blocks the access. It is very easy to implement and manage.

Since this can allow or block traffic dynamically, it is also called Dynamic Packet Filtering Firewall.

Cisco ASA is an example of a Stateful inspection firewall.

3. Circuit Level Gateways

Circuit Level Gateways work on the Session Layer of the OSI model. These firewalls use TCP handshaking to determine whether an IP packet is valid or invalid. It identifies whether a requested session is legitimate and takes the action accordingly.

The main disadvantage of this firewall is that it is not filtered Individual Packets. Therefore, it might pass a malicious packet throw it. Circuit-level gateways are almost obsolete and replaced by Next-Gen Firewalls.

4. Application Level Gateways

An Application Server (FTP, SIP, RTSP) is kept behind this firewall. We will configure the manual mapping of the destination port and destination address on the firewall. So, if anyone wants to access this server, he will never get the actual assigned IP and ports.

5. Next-Generation Firewalls

I’m sure you know about Next-Generation Firewalls (NGFW), which is a combination of the traditional firewall with advanced network monitoring and filtering devices. The Next Generation Firewalls can monitor and filter network traffic up to the 7th layer of the OSI Model, i.e, the Application Layer. Next-Generation firewalls have in-line Antivirus, Anti-Spyware, IPS, and URL Filtering filtering.

They also provide support for Sandboxing and secure our organization from 0-day attacks.

Palo Alto Networks Firewall, FortiGate is an example of a Next-Gen Firewall.

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• SSL Decryption on Palo Alto Next-Generation Firewall

Summary

In this article, we discussed, different types of network firewalls. Packet Filtering Firewalls, Stateful Inspection Firewalls, Circuit Level gateways, Application-level gateways, and then Next Generation Firewalls. We also discussed the Pros and Cons of different types of firewalls.

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