Dear readers of Tecnogalaxy, today we will talk about a very famous and important apparatus for computer security, the FIREWALL, which translated into English “firebreak”, comparable to a wall built inside a building to limit the spread of fires.

Computer firewalls perform the same function: they control data traffic in both directions to prevent fire (entering or exiting connections that are dangerous to the system) from causing damage.
If you use a Windows or MacOS operating system, your computer is protected by an internal firewall.
In some cases you will also have to change its settings or disable it in order to use some particular software.

When was the first firewall created?

In the late 1980s, firewalls were introduced to combat intrusions. The first generation was packet filter firewalls or stateless firewalls, the first being developed in 1988 by Digital Equipment Corporation.


The first statefull firewall (also called circuit-level gateway) was developed between 1989 and 1990 by AT&T Bell Laboratories.

But have you ever wondered what it is and what its function is?

In computer science and computer networks, a firewall is a hardware and/or perimeter defense software component of a network, originally passive.

A firewall can be compared to a kind of filter that controls data traffic, blocking dangerous or unwanted transmissions, all according to a series of specific rules.
Most firewalls already have standard rules by default, the end user can add other customizations (rules), to manage their needs.

Of course there are various types of firewalls, each of which analyzes certain characteristics of data transmissions.

The firewall interposes between the external network (the world of the Internet), and the internal network of the company or home.
From a theoretical point of view, the internal network is considered known, therefore safe, reliable and protected, while the external one (being indeed external), is the presumed source of potential threats, as overall it is unknown and insecure , not reliable.

Most firewalls use one of these two rules application criteria:

Default-deny: Only what is explicitly authorized is allowed, while the rest is prohibited.

Default-allow: Only what is explicitly forbidden is blocked, while the rest is allowed.
Default-deny is the most used policy because it guarantees more security and more precision in the creation of rules.

For this reason, when you first start an application that is connected to the Internet on Windows, the operating system shows you a message asking you to authorize or block the connection.
The second criterion allows easier and faster configuration of rules.

What kind of firewalls are there?

Firewall with packet filter: On the network data is transmitted through protocols, the most common is TCP/IP. The data set is divided into “packets”, (the sender contacts the recipient and when he accepts the connection), sends him the response packets.

Each packet has a label called (header) containing different information that allows the recipient to reconstruct the original data sent, including the IP addresses, the destination port and its transmission protocol. This type of firewall (packet filter), analyzes the data contained in these labels, makes a comparison with the filter rules set and decides whether to block or let the connection pass safely.

This type of firewall is reliable but is limited because it is exposed to several modern threats such as IP spoofing, (replacing an IP).

These limitations have been resolved by creating firewalls that also control the status of the connection.


These types of firewalls, “statefull inspection”, not only analyze data packets, but also analyze the status of the connection and the ports used on the various connected computers and transmission protocols. These types of firewalls are now considered industry-standard, and most firewall applications/software implement their functionality.


Dedicated to a single application, they function as intermediaries in the communication of data between this and the external network.
They do a deeper analysis and can block connections in real time. They are enterprise-class solutions, when the required degree of security is very high and you have powerful devices available, which will not be affected by the slowdown caused by firewall activity.


Known as “next-generation firewall”, this type of firewall features prevention and intrusion capabilities with application monitoring. They are software for companies or people with special needs, require supervision by experienced staff, they are compared to a building anti-theft system.

Unified Threat Management (UTM)

They are integral systems of cybersecurity, they also contain a firewall, they are different from the new generation firewalls because there are versions for end users of medium profile, simple to use and cheaper.

The Panda Dome model includes a customizable firewall, VPN services and antivirus protection, and application control and management features.
For more than 25 years, firewalls have been the first line of defence for network security and constitute a barrier between internal networks (secure and controlled), and external networks that can be trusted or not, such as the Internet.

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