Cyber Security

Firewall: what it is, how it works and how to choose the best one for your company

Firewall is a security system that aims to protect computer networks from suspicious or dangerous movements. In general terms, a firewall is software that controls data entry and exit, filtering what is safe and what is not, according to a set of predefined rules.  

When did it come about?

The creation of the firewall was a collective effort that was perfected between the end of the 80s and the beginning of the 90s.

The first version of the firewall, developed in the late 1980s by Mogul, Reid and Vixie, emerged with the aim of inspecting external connections and restricting access from external IP addresses to internal networks of Digital Equipment Corp (DEC).

Soon after, the new version, developed in the early 90’s, started to allow continuous connections. Thus, the circuit-level gateway firewall was born. Then, between 1991 and 1992, security proxies appeared, implemented in the firewall. From this implementation, it started to be commercialized.

Finally, in 1993 and 1994, there was an expansion of firewalls, which started to be used not only in corporate computer networks, but also in domestic networks.

What is the firewall for and how does it work?

Active protection is important to ensure the highest security of computer networks. After all, an unprotected network is more susceptible to attacks on your systems.

In practice, the firewall works as a protective barrier between networks , which protects your private network from what is not trusted. For this to happen, there is packet filtering — which is a procedure for prior analysis of the data transiting the network.

Difference between firewall and antivirus

Antivirus and firewall have the same objective: to protect the system. However, they act in different ways to ensure internet and computer security.

The antivirus is a software that detects , through the analysis of files and programs before their execution, hidden threats in these malicious software that try to invade the system. A firewall is a security feature that acts as a protective barrier against unauthorized access attempts to the computer network system.

firewall types

Now that you understand what a firewall is, know that there are several types and with different modus operandi meeting specific needs. Therefore, it is important to know each of the firewalls to identify which is the most suitable for your environment.

Firewall is just one of the ways to protect the computer network, but it must be used with other protections, such as antivirus.

Check out the top five firewall types:

Packet filtering firewall

The packet filtering firewall serves to control access to the network by inspecting incoming and outgoing packets , allowing or blocking access.

For this, the analysis is based on some criteria previously defined by the administrator, such as:

  • Allowed IP addresses;
  • package type;
  • Port number.

circuit-level gateway

Circuit-level gateway monitors elements of network protocol session initiation in order to identify whether the initiated session is secure . For example, one of the elements analyzed is the Transmission Control Protocol (TCP).

Circuit-level gateways are generally used in network security solutions alongside other firewalls, such as a packet-level gateway and a content-filtering gateway.

application-level gateway

Also known as a proxy firewall, application-level firewall acts as a mediator between external networks and computers . That is, it serves to protect network resources through actions such as IP address camouflage, message filtering, caching, etc.

stateful inspection firewall

The stateful inspection firewall stands out from other firewalls, such as packet filtering, because of its ability to track whether or not a packet is part of a TCP . In this way, the stateful inspection firewall is able to analyze each packet individually and identify important points, such as IP addresses and port numbers of the source and destination of the packet.

next-generation firewall

A next-generation firewall combines different features of traditional firewalls with new technologies such as, for example, intrusion prevention systems and encrypted traffic analysis. As a result, next-generation firewalls are able to detect attacks quickly and block threats quickly .

What is the most used firewall?

Because it is one of the most complete firewalls, due to its ability to unite several technologies in a single solution, the last generation firewall is usually the most sought after by most companies to ensure cybersecurity .

However, it is not because this is the most wanted that it is the best solution for everyone! The decision for a firewall must be made carefully , considering the security architecture , the needs of the institution and which firewall policies best meet these demands.

Advantages and disadvantages of the firewall?

You already know what a firewall is and what types exist, let’s see its main advantages:

  • Information access control;
  • Data security;
  • Checking remote connections.

Already in the list of disadvantages and limitations of the firewall can mention the following:

  • Compromise of the structure if it is not constantly updated;
  • Packet filtering can fail in some situations;
  • Interference with incoming data that is not a threat to the network.

How to know if there is a firewall on the network?

Virtually all network connections are firewalled. However, you need to check if they are enabled or not . For this, we have prepared a step-by-step guide on how to check in Windows 10:

  • Open the “ settings” ;
  • In the settings , select the “update and security” button ;
  • In update and security , select the “ Windows security” option and then “ Open Windows security” to see the firewall settings;
  • Finally, under the “ Network” tab , click the toggle to turn Windows Defender Firewall on or off .

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