The internet is effectively a public network, meaning that any connected device can find and connect to any other connected device. A firewall is a barrier between the internet and your computers or network – preventing unauthorised visits to or egress from your systems.
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Ensure your firewall is appropriate for your needs and is switched on at all times.
A firewall protects your organisation against:
Hackers breaking into your computer or network.
Worms – types of viruses that spread from device to device online.
Some outgoing traffic originating from a virus infection.
What a firewall does NOT do:
A firewall is not sufficient on its own to guarantee security, but constitutes the first line of defence. You also need to take the other protective steps outlined on this website. Remember that a firewall provides little or no protection against the following:
When you have granted permission for other computers to connect to yours.
When it switched off, disabled or contains many exceptions or open ports.
Most malware and spyware installations.
Any kind of online fraud or criminal activity.
If you or a virus has created a ‘back door’ through the firewall.
People with physical access to your computer or network.
Data introduced to the computer other than online, for example via USB connected devices, CD/DVD etc.
Attacks after a network has been compromised.
Traffic that appears to be legitimate.
However, none of above constitute a reason NOT to install a firewall, as you should always assume that your ISP does NOT provide any kind of firewall.
Types of firewall
Personal firewalls should be installed on each computer that is connected to the internet and monitors (and blocks, where necessary) internet traffic. They are also sometimes known as ‘software firewalls’ or ‘desktop firewalls’.
Windows Firewall is a basic personal firewall. It is free, included with Windows operating systems. In Windows 10, Windows 8, Windows 7 and Vista, the Firewall defaults to active, so you need not worry about configuring it yourself.
If you wish, you could replace Windows Firewall with another personal firewall of your choice, including the type incorporated in some internet security packages, or standalone firewall software which can be downloaded from the internet, some of which is free of charge.
Medium-sized and large businesses may need a hardware firewall – in addition to personal firewalls – depending on the configuration of your IT infrastructure. If in doubt, seek professional advice on selection installation and configuration of the most suitable one for your business needs.
Check if your Windows Firewall is switched on
In Windows 7, 8 and 10, go to Control Panel, select System and Security, then select Windows Firewall. The Windows Firewall state is indicated under Home or work (private) networks.
In Windows Vista, go to Control Panel, select Security, then select Windows Firewall. The Windows Firewall state is indicated.
If you are still running Windows XP, go to Control Panel, select Security Center. The Windows Firewall state is indicated.