Types of Network Firewall

Network Firewalls are the devices that are used to prevent private networks from unauthorized access.  A Firewall is a security solution for the computers or devices that are connected to a network, they can be either in the form of hardware as well as in form of software. It monitors and controls the incoming and outgoing traffic (the amount of data moving across a computer network at any given time ). 

The major purpose of the network firewall is to protect an inner network by separating it from the outer network. An inner Network can be simply called a network created inside an organization and a network that is not in the range of an inner network can be considered an Outer Network.

Types of Network Firewalls

Here are the main types of network firewalls, organized by how they function and where they're deployed:

1) Network Placement

Network Security is the process of protecting networks, systems, and data from unauthorized access, attacks, and damage.

• Packet Filtering Firewall
  This is the most basic type. It checks packet headers—like IP address, port number, and protocol—and decides whether to allow or block them. Think of it like checking someone's ID at the gate. If the name and ID match the list, they’re allowed in, no questions asked.

• Stateful Inspection Firewall
  Goes a step further. It monitors active connections and makes decisions based on the context of traffic. Imagine a hotel that remembers you checked in earlier, so it doesn’t question you every time you enter.

• Proxy Firewall (Application Level)
  This acts like a middleman between user and destination. It fetches data on your behalf while filtering dangerous content. Like asking your assistant to go to a store for you—they check the item first before handing it over.

• Circuit-Level Gateway
  Validates if a connection is successfully established (like TCP handshake), but doesn't inspect actual data. Like confirming someone is calling from a known number without listening to the call.

• Web Application Firewall (WAF)
  Specifically protects websites and web apps from attacks like SQL injection or cross-site scripting. Imagine a form guard that checks what users type before it reaches your website—blocking any harmful tricks.

• Next-Generation Firewall (NGFW)
  Combines traditional firewalls with modern features like app control, intrusion prevention, malware detection, and encrypted traffic inspection. It’s like a security team with surveillance cameras, ID scanners, and behavior monitoring—all working together.

2) Network Firewall

A Network Firewall secures the perimeter, while a Host-Based Firewall protects the endpoint.

• Network Firewall
  Protects a whole network—usually placed at the entry/exit point between your internal systems and the internet. Picture it like a guard standing at your building's main entrance.

• Host-Based Firewall
  Installed on individual devices like laptops, servers, or mobile phones. It protects only that one system. Think of it as having a security app that watches over just your phone, not the whole office.

3) Data Filtering Method

All three of these firewall types work to control network access, but they differ in their placement and scope.

• Perimeter Firewall
  Sits at the edge of your network, filtering traffic coming in and out from the internet. Like a fence with a gate that controls who gets into your property.

• Internal Firewall
  Placed between different segments inside your network, such as departments or sensitive zones. Imagine every department in a company having a door lock with access rules.

• Distributed Firewall
  Instead of one firewall at the edge, security rules are applied at multiple endpoints across the network. Like installing security alarms in every room of your house rather than just at the main door.

4) Form Factors

A program installed on a computer or server that protects it from network threats.

• Hardware Firewall
  A physical box or appliance that connects to your network. Often used in large or office environments. Think of it like a security gate at the main entrance—visible, strong, and standalone.

• Software Firewall
  Installed as a program on a device or server. Easier to set up and ideal for individuals or virtual setups. Like installing a firewall app on your laptop to control its own internet access.

Working of Firewalls

Firewalls can control and monitor the amount of incoming or outgoing traffic of our network. The data that comes to our network is in the forms of packets(a small unit of data), it is tough to identify whether the packet is safe for our network or not, this gives a great chance to the hackers and intruders to bombard our networks with various viruses, malware, spam, etc.

Capabilities of Modern Firewalls

Since they were first created, firewalls have been a key part of network security. As technology has advanced, so have the capabilities and methods of deploying firewalls.

With these advancements, many different types of firewalls have emerged, making the options sometimes confusing. Different firewalls serve different purposes, and one way to differentiate them is by looking at what they protect, their form, where they are placed in the network, and how they filter data.

Organizations might need various types of firewalls to ensure effective network security. It's also important to remember that a single firewall product can include multiple types of firewall functions.

Limitations of Network Firewall

Here are the demerits of Network Firewall

• Cost: Depending on the type of firewall, it can be costly, usually, the hardware firewalls are more costly than the software ones.
• Restricts User: Restricting users can be a disadvantage for large organizations, because of its tough security mechanism. A firewall can restrict the employees to do a certain operation even though it's a necessary operation.
• Issues With The Speed of The Network: Since the firewalls have to monitor every packet passing through the network, this can slow down operations needed to be performed, or it can simply lead to slowing down the network.
• Maintenance: Firewalls require continuous updates and maintenance with every change in the networking technology.  As the development of new viruses is increasing continuously that can damage your system.