News

• Factsheets

  Download our factsheets on key online security issues.

• Quizzes

  Test your knowledge with these quizzes.

• Self-assessment tool

  For small and medium businesses.

A firewall acts like a security guard at the door of your house; it checks who and what enters or leaves.

A firewall is a piece of software or hardware that sits between your computer and the outside world and acts as the gatekeeper for all incoming and outgoing traffic.

A correctly configured firewall will prompt you when it detects an unauthorised computer or program trying to access your computer or a software program is installed on your computer that tries to make an unauthorised outside connection.

If you are a home user, using a firewall and having it permanently turned on is the most effective and important first step you can take to help secure your computer. Always use a firewall, as well as anti-virus and anti-spyware software. The more lines of defence you have in place, the harder it is for hackers to get in.

How does a firewall work

A firewall monitors all incoming and outgoing traffic on your computer using a predefined set of rules. A firewall can block information or access requests that do not conform to these rules.

There are two types of firewalls—software firewalls or hardware firewalls. Many people use both types as each offers different security features and benefits.

Hardware firewalls

Many computers and other hardware such as routers and modems have built-in firewall capabilities. These firewalls can be effective with little or no configuration.

• For people with broadband connections, the dual function modem-router provides connectivity to the internet and the ability to restrict inbound and outbound connections in the same way as a firewall.
• Routers use private address ranges by default for the internal network as an additional security feature which helps protect computers on your home or business network.

If you have doubts about hardware firewalls on any device in your home or office, look up the website of the hardware vendor and do a search for the term 'firewall'. For further information about how to set up the firewall on your broadband router, see the factsheet, Securely configure your broadband router.

Software firewalls

Software firewalls can be installed on your computer and can be configured according to your needs. Many software firewalls have user defined controls for setting up safe file and printer sharing and to block unsafe applications from running on your computer. Software firewalls may also incorporate privacy controls and web content filtering.

• Before installing your software firewall check what system resources it will require to run and any incompatibilities with your operating system. A good software firewall will run in the background and use only a small amount of system resources.
• Software firewalls will only protect the computer they are installed on. If your have more than one computer on your home network or connected to the internet you will need to install a software firewall on each one.
• It is important to configure your firewall properly so it can protect your computer. Some firewalls have tutorials that can help you configure your firewall properly. You can also look into the help section in your firewall program.
• It is important to monitor a software firewall once it is installed. Check it is still connected and working correctly and download any updates available from the software vendor.

There is a wide range of firewall software available that provides a good level of protection. Some software is available as 'freeware', i.e. at no cost to home users, although some of these may have fewer functions. For further information on free security software for personal (non-commercial) use see:

 Free security software (PDF, 616KB)

How to check you have a firewall installed

To check if your computer has a software firewall already installed look in the main program menu for any program name that mentions security or firewalls. Some common brand names for software firewalls for home users include McAfee, Symantec, Kaspersky, AVG or ZoneAlarm.