A firewall can be a hardware or software device. A hardware firewall is a unit that is connected between the network and the device for connecting to the Internet. A software firewall is a program that is installed on the computer with the Internet connection. Similarly, there are computers with specific software programs that are placed behind the router and whose only function is to provide the network firewall.
This is the most common type of firewall, as they are not only cheaper but also easier to install. However, they have some disadvantages. For example, they use a large amount of system resources and sometimes, do not run correctly and can cause compatibility problems with other types of software installed on the computer.
Modern operating systems like Windows XP and Linux incorporate basic firewall solutions. In some cases, like freeware firewalls, they are very powerful and flexible, but require in-depth knowledge of networks and the ports used by these applications. To simplify configuration, they usually have web interfaces that make it easier for users to manage them, although this can result in reduced functionality.
Hardware firewalls are used more in companies and large corporations. These devices are usually placed between the router and the Internet connection. As they are dedicated security devices, they are optimized to carry out firewall functions and do not use up resources on personal computers.
Their biggest drawback is maintenance, as they are difficult to update and configure correctly.