1.1 Personal firewalls
Most operating systems come with a firewall that is installed as part of an operating system.
This firewall is only able to protect the computer it is installed on (and any devices attached to it) from an attack, so it is called a personal firewall. It is not intended to replace a network firewall which prevents attacks from outside of the network (such as from the internet).
Personal firewalls are especially useful for people with portable computers which will inevitably be connected to a wide range of computer networks. While we all hope and, to some extent, trust the people responsible for maintaining these networks to maintain a safe system, we cannot be sure that these networks are not compromised. The personal firewall on our own computers therefore adds a layer of protection between our personal data and a potentially untrustworthy (but useful) network.
Personal firewalls are the responsibility of individual computer users. If you have complete access to your computer’s settings then it is entirely possible to turn off the personal firewall and leave your computer vulnerable.
In the next sections, you’ll learn how to check that your default personal firewall installed with your computer is running correctly.