The concept of firewall is not part of the dictionary prepared by the Royal Spanish Academy ( RAE ). The institution, however, does include its equivalent in Spanish: firewall .
A firewall is a computer program or hardware that protects a computer or network from intruders. This is a system whose function is to block unauthorized access to the equipment or infrastructure in question.
The firewall, appealing to various criteria, is responsible for controlling data traffic . The information that reaches the firewall is analyzed by the system, which decides whether to allow passage or prevent it according to the determined security criteria.
There are various types of firewalls that apply different methodologies. It is possible to opt for a permissive policy that enables all data traffic except that which is specifically detailed, or for a restrictive policy that rejects all traffic except that which is explicitly endorsed. This second option is the safest.
In relation to the above, we cannot ignore the existence of several different types of firewall, among which the following stand out:
-State inspection firewall. It also goes by the name of stateful inspection firewall and what it does is block traffic taking into account aspects such as the port, the state or even the protocol as well as the restrictions previously established by the administrator. It carries out its work from the moment the equipment in question is turned on until the connection is completely closed.
-Proxy firewall. This category includes those that function as a gateway between two networks and based on a very specific application. Hence, they are responsible, for example, for avoiding a connection that is outside the aforementioned networks.
-Latest generation Firewall. The acronym NGFW is also known as this other type of firewall that is not only capable of detecting attacks but also stops all types of threats. In addition, it prevents intruders, includes techniques to deal with changes that may occur in threats, and performs an exhaustive state inspection.
-Firewall for unified threat management, which also responds to the acronym UTM. Its ease of use and even its simplicity are two of the main characteristics of this type, which prevents intrusions and, at the same time, is capable of including functions typical of a state inspection firewall, for example.
It can be said, in short, that a firewall is a traffic filter . An application or an individual who wants to access a computer equipment or a network without authorization, in this framework, cannot advance thanks to this system.
This capability alone, of course, does not guarantee security . An attack that arrives through traffic that does not pass through the firewall can cause damage, for example. Also a virus that circulates through an internal network. Even a misconfigured firewall puts a computer at risk.
Examples of firewalls are Agnitum Outpost, Comodo Firewall, ZoneAlarm or AVS Firewall.