What Is a Firewall? A Manual for Dummies

by Kay Lee

A firewall is a set of tools for monitoring and filtering network traffic according to predefined rules.

What types of firewalls are there?

There are software firewalls that are installed on a computer, and hardware firewalls in the form of a separate external unit.

Firewalls serve for various purposes and can:

  • Work as a switch;
  • Filter network traffic and analyze IP addresses of incoming and outgoing requests;
  • Monitor gateways of the session and application level;
  • Perform dynamic filtering of network packets.

Network and client firewalls

Firewall (host-based) can be integrated into the operating system or installed additionally to protect one client computer.

Also, the firewall (network) can be installed on the network and act as a network gateway.

A separate computer can act as a network firewall and have a name (PC-based). Or the network firewall can work on a separate hardware platform (ASIC-accelerated).

Firewall functionality

The primary function of a firewall is to protect a computer or networks from external or internal attacks.

What does a firewall do, then?

  • Controls access to open services of a network node.
  • Allows you to set a set of rules for working with the necessary services.
  • Records external and internal network attempts to penetrate the system.
  • Blocks attempts to remove information about the protected device or network.
  • Can display knowingly false information about client networks or devices.

Firewall and antivirus

The firewall cannot scan the system for malware or perform actions with virus-infected files. Various antiviruses are used for such purposes. It is important to remember that the firewall cannot protect the computer from infected programs that the user installs.