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Computer firewalls: What are they, what are they for and why is it important to have them?

Computer firewalls: What are they

In order to manage access of different users to network services or to be able to register all the entries and exits of data packets to it, it is necessary to install a firewall.

A firewall is not only capable of the aforementioned, but it can also control the different types of protocols used in a network and manage the applications that can access the Internet.

In this article we will talk about the most important concepts you should know about a firewall, its implementation and configuration, and you will also know if an antivirus is the same as a firewall, among other things.

What is a computer firewall and what is it for?

A firewall or commonly called in English “firewall” are supplements or hardware devices or software that allows to manage all inputs and outputs between two networks or between two or more computers belonging to the same network.

That is, with a firewall we filter all the inputs and outputs that do not comply with certain “rules” that we have previously established. If a data set complies with the established protocol, you can enter or leave the network we want to protect.

With this concept we can define what a firewall is installed for. Among the different reasons we can highlight:

  • A firewall protects the security and privacy of the computers and networks on which it was installed.
  • Protects all information or data blocks that belong or are managed within the network. For many companies this point is the main reason why they use a firewall.
  • With a firewall you can prevent access from intruders or hackers that could affect computers or computers. network.

Avoid so-called “DDoS attacks” in which legitimate users cannot access the network or computer.

Firewalls vs. Antivirus Are they the same tool? Differences

Cortafuegos vs Antivirus ¿Son la misma herramienta? Diferencias

While the firewall and antivirus belong and serve computer security, there are substantial differences between them.

To clarify the idea we will detail some differences:

  • The antivirus is software that is installed on a mobile or on a computer , while the firewall is software, > but it can also be a hardware . The latter is less used in cell phones.
  • The mission of the antivirus is to detect a virus or any malware and destroy it, while a firewall your mission is that you cannot Enter or exit information if they do not comply with the rules
  • They have one point in common, in networks and computers only one of each is needed . That is, it is not necessary to install several of these because we could have adverse results.
  • The firewall with the antivirus is complementary to each other, that is to say to have an efficient computer security, it is The presence of both is necessary. This complement system is highly recommended for companies.

History and evolution of firewalls, how many generations have existed until now?

In 1980 the term firewall began to be used for the first time , at this time the Internet was a new network from the point of view of its use and connectivity.

The first firewalls that existed were the routers , which kept the different networks to which they belonged separated from each other.

At the end of the decade of the 80s there were important attacks on Internet security , there are different examples in which it was possible to manipulate from spy systems to the large-scale attack of what is known as virus “the Morris worm” , which was not malicious.

From this moment on, new generations of the firewall began to emerge , they differ from each other by their degree of progress and approach to security.

Historia y evolución de los firewall, ¿Cuántas generaciones han existido hasta ahora?

We detail, then, each of these generations of firewall.

First Generation

This generation targets network firewalls, which were born in 1988, the Digital Equipment Corporation (DEC) company designed a system for packet filtering. This generation is known as “packet filtering.”

The engineers developed rules to be able to filter the data packets that travel through the network , that is, if a package matches the rules that were previously established, the package will be accepted, so otherwise it will occur to its silent discard or they will part with it and it will be rejected.

For this last case, a response with an error code is issued to the sender of that data packet.

Second Generation

The second generation arises between 1989 and 1990 , engineers of the laboratory firm «AT&T Bell» designed a firewall in which the individual packages will be placed inside of a series of packages.

This type of technology is commonly known as packet status inspection, hence the name of “status firewall” . It consists of keeping a record of all the connections that go directly through the firewall registering if the package is wrong or not.

Third Generation

The third generation is known as “application firewall” , the firewall acts on the layer called “Application” of the OSI model , which shows the different stages that has a network in operation.

This firewall is aimed at detecting the transfer protocols of the files, and if a protocol is not desired it will be rejected immediately.

The great advantage of these firewalls is that they can filter higher layer protocols, always speaking according to the OSI model. That is layers like HTTP, TCP and TFTP among others.

It has a disadvantage that is the slowness that they present with respect to the Second Generation firewalls.

What are the main types of firewalls and their characteristics?

There are two types of firewalls, each of which has particular characteristics. We detail you below:

Software Firewall

Software firewalls are programs that are usually loaded with the operating system . For example, Windows brings its built-in firewall for free, it does not present major problems at the time of its configuration and in most cases this type of software is free , although there are also paid versions in which can modify or adjust the needs of each user.

The main job of these firewalls is to control all data traffic that moves through networks in relation to the Internet . It is also aimed at blocking network elements and connections that may have a potential problem for the computer or the network to which it belongs.

Almost always do not need to add hardware for installation, it is done in a few steps that are not complicated. In the paid versions the provider grants certain benefits that perfectly fit the needs of the client making the steps even easier.

Hardware Firewall

When we talk about a hardware firewall we are talking to all those firewalls that are not installed on a computer that belongs to a network, but we are talking about those that are installed on physical devices that we use for the Internet connection, for example, the router.

The main advantage of these firewalls is that all the computers connected to the router that already have the firewall installed will have the firewall on each of them directly .

To configure the parameters the firewall on the router is recommended to be done through professional people in the sector . If for some reason the configuration is not correct, network users will not be able to carry out their work in a normal way because their activities will be suspicious for the router.

Advantages and disadvantages of using a firewall Are they really effective?

Ventajas y desventajas de utilizar un firewall ¿Son realmente efectivos?

Like all computer stuff, firewalls have their advantages and disadvantages when installed on a network.

Next, we will name the most important ones:


We can mention the following as strong points of a firewall:

  • One of the main reasons why a firewall is installed in a company is that they define what information each of the users of the network will handle
  • Use the direct access to the protocols that will be used on the network
  • Control the intrusion entry
  • Yes the source is not legitimate it will block all the information that comes from it
  • Protect the hardware , since, if an intruder launched a virus, it can cause irreparable damage to the equipment physicists With the implementation of a firewall you can stop the virus


Among the disadvantages we will have to mention:

  • The firewall does not protect against attacks when they do not pass through the firewall
  • If there are network users who are negligent >, the firewall will not protect from misuse of them since they were able to correctly enter the network

If there is income from legitimate users, they can create copies of the information and the firewall will not be able to protect on the subject

List of the best firewalls you can install on your computer span>

Lista de los mejores cortafuegos que puedes instalar en tu ordenador

We present the list of the best firewalls you can install on your computer or network. Each of them have really very good characteristics, which makes them unbeatable when filtering blocks of data.

Windows Firewall Defender

The firewall par excellence, is included or preinstalled with the Microsoft operating system . It is free and considered one of the most efficient and least invasive for the user.

To activate the firewall we will follow the following steps:

  • On the screen we look for the Windows logo located at the bottom left
  • We select “ Start
  • We look for “ Settings ” and click
  • Next, we choose“ Update and security ”
  • Windows Security
  • And we choose ” Firewall and network protection
  • We select the network profile we need, and then
  • We change the setting in “ Windows Defender Firewall”
  • We click on “On”

This software is produced by the Check Point company, and is listed as one of the oldest and most efficient existing today.

They have two versions, one free that includes intruder detection and can control which programs can create connections within the network or within the computer. It also protects against sending data packets.

For the paid version it also offers more complete services and can be customized according to the user’s requirement. It is available for the Windows operating system.


This an open source firewall allows blocking traffic to and from the internet generating a blacklist of hosts, also determines a list of IPs that can be rejected.

It is available in a free version for Windows.

Download PeerBlock Windows


Considered by many to be the best free firewall that exists today. Among its advantages it has the characteristic of being a program that is not complicated for its installation and use is easy and above all it is fast.

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