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Network Security 101: The Evolution of Different Firewall Types

Network Security, with time, has become a more prominent term to individuals, institutions, and businesses. With the number of attacks from the public networks over private network firewalls increasing, there has always been the necessity to set up stronger and better security systems.

In achieving this, firewalls have gone through quite a lot changes in the recent past. In this article, we show you the evolution of different firewall types which focus merely on providing better ‘security’ to your private networks.


The Different Types Of Firewalls:

#1 Access Control Lists

The ACLs were the basic and the earliest firewalls that ever existed on routers. They are so different compared to any modern day firewalls but the basic idea on which they were built has been carrying forward ever since, i.e. packet filtering.

These are particularly good for scalability and performance but unfortunately, can read nothing more than the packet headers.

As traffic enters, these ACLs screen them based on protocol, source/destination IP Address etc, and permit or deny each individual packet.

#2 Proxy firewalls

The Proxy Firewalls are indeed the most secure types of firewalls. The way a proxy firewall works is different from all the other firewall types.

These firewalls are employed at the application layer of the OSI model. Hence a proxy firewall can also be called the application firewall.

Proxy firewall, just like any other firewall accepts or denies traffic considering each individual packet separately. The reason for heightened security in this type of firewalls there is no direct contact between network systems.

The proxy server manages, or in other words brokers all the connections between the network and the outside world. Thus there’s no harm to a particular network either from a public network or any other wing of the private network.

The added security capabilities mean that these firewalls slow things down. Also their complexity of not allowing more than a few popular network protocols could give us a real headache!

#3 Stateful inspection firewalls

The Stateful Inspection Firewalls are sort of advanced versions of the ACLs. They are also referred to as dynamic packet filtering firewalls.

As opposed to static packet filtering firewalls, these firewalls instead of just checking the headers of packets can also monitor the exact state of all active connections.

These firewalls monitor both the incoming and outgoing packets for a period of time. In the process of tracking the outgoing packets, the required incoming packets are identified and only those packets are allowed through the firewall.

Their ability to prevent port scanning, by keeping the ports closed unless requested by incoming packets adds additional defense.

#4 Unified Threat Management (UTM) Firewalls

These are the best security solutions, where in the firewall is included with an antivirus, data leak prevention, load balancing, anti-spam, VPN etc.

The resultant product is a single console through which the entire complexity is reduced. With an UTM in hand, you can forget about installing all the software separately and then their maintenance.


All you have to do now is understand this one product in detail and that’s all it takes in establishing the entire security system for your private network.

There are disadvantages also though with this approach, where the single point of failure comes in.The Unified Threat Management solutions are also referred to as Next Generation Firewalls.

2 thoughts on “Network Security 101: The Evolution of Different Firewall Types

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