What is a Firewall?

See in Portuguese.

Probably you may have seen on your computer any information about firewall. But, you know what it is? We will see in this post how it works.

The Firewall does not have that name for nothing. It is a safety device, physical or logical, with the function to filter the data packets entering and leaving the computer. According to the rules that are inserted in it, the firewall checks each packet that tries to enter or leave to identify whether this may or may not go his way.

firewallAs we speak, it can be physical or logical. If it is physical, it is a router or computer that is connected to your network to protect all devices of this. On the other hand, it may only be a software installed on a machine. In the latter case will protect only the computer where it is installed.

The Firewall is a very important tool for the security of your data, but can not be used in isolation. The anti-virus should complement security. The two being updated, work in harmony. Obviously, safety certainty when browsing the Internet will never be full and, even when installed anti-virus and firewalls properly updated, yet we are not completely immune.

With the evolution of how we use the Internet, it was necessary to include a native firewall in operating systems. People began to increasingly use broadband, sending and receiving data at much higher data and hence becoming more susceptible to threats. Thus, even as normal user and not knowing the existence of the firewall, you can rest assured. At this point, the firewall is checking all packets entering and leaving your computer to the release (may not).

Example firewall physical (hardware).

Understand how your firewall works

To clarify understanding, let’s imagine that the firewall is a security of a business meeting. At this meeting, there is a list and the following rule is passed to the security: “Only allow access to people who are listed as permitted.” However, this list, which defines whether the person enters the meeting or not, is the number of chair that will sit. However, this list is consisting that the chairs 25 and 8080 can not enter at all. When they arrive at the entrance, they are prevented from pursuing and do not enter the meeting.

In addition, still in the building members who participated in the previous meeting and they must go through the same security. In another list on the other hand, security has described that the members of the seats 80 and 442 of the previous meeting can not leave the building. The moment they are going through security to go away, will be barred.

In the example above, we see that the firewall checks all data inputs and outputs, which in our example were replaced by people. This method does not stop a hacker to get in ‘disguise’ the meeting as a guest and the seat number that should be used for that person. In this case the firewall allows access and your system is hacked.

In the above situation, we exemplify the seats as the doors, but it takes you to understand one thing: even using chairs, these can be accessed infinitely different from a real chair, which can only be used by one person. Do not get the feeling that the door only good for one package. This is not true. That’s why the port has this name: for anyone in or out.


Native firewalls already have a preset standard ports that should be closed, because these doors usually many hackers invade the system.

Firewall: is only good with antivirus!

As we have seen several times here, we know that only with the firewall and updated anti-virus running on the same machine do we have a little more security.

firewall3So, for you to keep as far as possible the “dirt” of the Internet, it is necessary to maintain an anti-virus and firewall updated on your machine. Also, keep “healthy” habits to your computer. These habits will be studied soon. Until next time!


tecmundo.com.brtecmundo.com.brwindows.microsoft.compt.wikipedia.orgyoutube.com. Images: firewall 1, physical firewall, firewall 3, firewall 4.

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