What is a Firewall and how does it work?

What is a Firewall and how does it work?
5 min read

A firewall, also called a firewall, is a system whose function is to prevent and protect our private network from intrusions or attacks from other networks, blocking access to it.

Allows incoming and outgoing traffic between networks or computers on the same network. If this traffic complies with the previously specified rules, it will be able to access and leave our network, if it does not comply, this traffic is blocked.

In this way we prevent unauthorized users from accessing our private networks connected to the Internet

It can be implemented in the form of hardware, software, or a combination of both.

What are the functions of a Firewall?

  • Create a barrier that allows or blocks attempts to access information on your computer.
  • Prevent unauthorized users from accessing the organization's computers and networks that connect to the Internet.
  • Monitor communication between computers and other computers on the Internet.
  • View and block applications that may generate risk
  • Warn of connection attempts from other computers.
  • Warn you of connection attempts by applications on your computer that connect to other computers.
  • Detect applications and update routes to add future sources of information

Traffic filtering methods

Firewall Policies:

They allow you to block or allow certain types of network traffic not specified in an exception policy. The firewall suspends any communication request that does not come from the internal network or from the system itself so that nobody will be able to scan the network, from the outside only the IP address of the firewall can be seen, no internal resources within the network can be seen. It also defines which firewall features are enabled or disabled.

Anti-Spam Firewall:

This service protects against spam, phishing, technology comes from recurring pattern detection (RPD).

Capacity scans through millions of new patterns daily to block all infected messages in real time. In addition, antispam is applied to the sender IP based on reputation to eliminate more than 80% of spam, avoiding suspicious messages.

Antivirus Firewall:

Service that some Firewalls incorporate, is the first line of defense to protect the internal network against attacks that come from the Internet or WAN link.

Content Filtering:

It allows administrators through a system of exclusion rules to easily block some types of web content without having to manually block each individual URL. Inappropriate websites and social media websites are blocked quickly and easily. The firewall distinguishes between problematic, suspicious or unsafe content.

WAP Managed Service:

Allows you to control WAP devices and manage usage for authorized users and defined services.

IPR services:

This is the name given to the Deep Package Inspection procedures (IPP or DPI for its acronym in English: Deep Package Inspection). It allows the administrator to control specific applications known as (trojans and backdoor applications) that can infiltrate your internal network.

Its function is to add a second layer of security to the system, checking the deep content of the received information packets, giving the administrator the flexibility to block specific programs that are not allowed on the network.

Firewall Types:

We differentiate between two types of firewalls, intended for different types of infrastructures and network sizes.

Hardware Firewall:

This kind of system is installed in the routers that are used to access the Internet, all the computers that are behind the router will be protected but the firewall. Most routers already come with the firewall installed, it is recommended to have routers with the firewall already installed due to the complexity of installing it later.

Software Firewall:

We find the free ones, they are basic firewalls for personal computers, which monitor and block Internet traffic whenever necessary. Currently the vast majority of PCs already have a firewall installed regardless of the operating system installed.

The paid ones have a similar operation, but adding higher levels of control and protection in addition to a much higher control over its configuration and operation. They are used at the business level for greater protection of organizations, since those for free use fall short of benefits.

They can be easily integrated with other network security products and do not require hardware for installation.

It is possible and highly recommended to have both a hardware firewall and a software firewall active simultaneously for added protection.


A correctly configured and managed Firewall allows the confidential information of any organization and its users to be kept safe. Thanks to the firewall we can

  • Define a barrier keeping unauthorized users out.
  • Monitor and log services used to use the Internet, FTP and other protocols.
  • Prevent attacks on the private network from other external networks.
  • Control the security of your network and equipment individually when any suspicious activity occurs.
  • Control Internet usage by blocking or unblocking inappropriate or appropriate material.


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