Host-based Firewall

Overview

A host-based firewall is a software agent that runs on a device to prevent certain malicious data from being sent to or received by the device. This section discusses two types of host firewalls:

• Network

• Web browser

Host-based network firewall

A host-based network firewall runs on a device to prevent certain network-based activity from being received by the host it’s running on. This type of firewall isn’t to be confused with a general network-based firewall, which focuses on the entire network. The focus of a host-based network firewall is the individual device it’s installed on, and these types of firewalls are bundled with most modern operating systems.

How it works

Firewalls can be set to allow traffic only from specific IP addresses and ports. A port can be referred to as a service running on a device. A web server, for example, is a service and by default, it uses port 80. With a firewall, most of the traffic inbound to the device, including malicious traffic, is blocked. If tuned correctly, the firewall only allows legitimate traffic through.

When a new device is connected to the internet, it only takes a matter of seconds until network logs show evidence of scans, probes, and generic attacks from IP addresses located throughout the world. To protect the device from this type of malicious activity, a firewall blocks all unnecessary ports, thereby reducing the device’s attack surface.