What is a firewall?
A firewall is a system or device that controls unauthorized outgoing and incoming traffic on a LAN network.
LAN or Local Access Network are the ones that we have at our homes, it includes from the router to the different devices that we may have connected to it, both by cable and by WiFi.
The term “firewall” refers to a computer security system that prevents unauthorized access to our LAN, that is, from the outside (WAN). In this way, the firewall does just that by placing a virtual “wall” to connections that are not authorized to send traffic to our LAN.
WAN or Wide Area Network finishes in the router that we have at home, from the router inwards everything is LAN, which is what this system protects.
Mostly all routers come with a firewall activated and preconfigured by the ISP (internet provider), although we can manipulate it to enable external connections.
This is done by opening ports, or by using a DMZ (Demilitarized Zone), which allows traffic to flow between devices on the LAN and those on the DMZ and WAN. By default, the router’s firewall blocks all unwanted traffic and acts as a good firewall.
In Windows, IOS, or any other operating system, we can find firewalls installed as standard, immovable.
This is done so that each device has additional protection, so it is highly recommended to have it activated for both public and private networks.
Exceptions can be added to suit the consumer from the OS’s firewall, but it is recommended to have prior knowledge of what is being manipulated, as it can lead to contracting computer viruses.
What is a firewall for?
A firewall serves to block unauthorized traffic to our LAN network.
It is 100% effective for restricted traffic but it does not cover any type of computer attack, far from it, but it is a low-cost measure that is implemented in operating systems and routers, among others.
It should be clarified that a firewall does not protect data traffic that does not pass through it, because it cannot even control it.
This means that our devices can be easily infected through flash drives or any other type of external storage. There are many computer attacks of various types, if a virus enters through the USB, through any external storage, the firewall will not detect it.
A firewall is not something supplementary to antivirus, but complementary. Both security methods are highly recommended on any computer, whether or not it has an Internet connection. A specific antivirus protects against those viruses that the firewall, in general, cannot detect, so they complement each other perfectly. We posted more tips on how to increase home internet security.
Firewalls typically have two action policies, one restrictive and one permissive. The former blocks all non-consensual traffic while the latter allows all traffic except that which is denied. This can be easily done from the Windows firewall settings, for example.
A computer virus can have many objectives, from obtaining personal information, credit cards, files… Once it enters the system, the virus can send information to the WAN (generally the Internet) with all the data collected, which it can do that your internet connection is quite affected, although that would be the least of your problems.
