What is a Firewall?
Protecting you quietly
A firewall is very important. There are two types of firewalls: hardware firewalls and software firewalls. Your router functions as a hardware firewall, you can also purchase stand-alone devices, while Windows includes a software firewall. There are other third-party firewalls you can install, too.
A firewall, either software or hardware based controls the flow of communications across networks of computers, everything that goes in and out of your computer is monitored. The firewall monitors all this information traffic to allow ‘good data’ in, but block ‘bad data’ from entering your computer. Another way of looking at a firewall is as a dedicated security guard who stops anyone coming into your computer if they’re not on the guest list, and anyone leaving if they don’t have permission.
How does a firewall work?
Once your computer, laptop, tablet and even smartphones are connected to the internet they are visible to every other device that is also connected. Because the internet is a public network, any connected computer can find and connect to any other connected computer. A firewall sits between a computer and the network or internet to control which computers can connect to it and what services they can use.
A correctly configured firewall will prompt you when it detects an unauthorised computer or program trying to access your computer, or a software program installed on your computer that tries to make an unauthorised outside connection.
The following illustration shows how a firewall works:
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.
Because the internet is a public network, any connected computer can find and connect to any other connected computer. A firewall is a barrier between the internet and your own computer or network. Think of it as a highly dedicated security guard who stops anyone coming into your computer if they’re not on the guest list, and anyone leaving if they don’t have permission.
Get started... Ensure your firewall is switched on at all times.
A firewall protects you against:
• Hackers breaking into your computer.
• Worms – types of viruses that spread from computer to computer over the internet.
• Some outgoing traffic originating from a virus infection.
What a firewall does NOT do:
A firewall isn’t sufficient on its own to guarantee security, but it is the first line of defence. You also need to take the other protective steps outlined on this website. However, a firewall provides limited or no protection against the following:
• If you give permission for other computers to connect to yours.
• If it is switched off, disabled or contains many exceptions or open ports.
• Most viruses.
• Spyware installations.
• Any kind of fraud or criminal activity online.
• 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, eg via USB connected devices, CD/DVD etc.
• Attacks after a network has been compromised.
• Traffic that appears to be legitimate.
However, none of these things give a reason NOT to install a firewall, as this alone is not enough for complete security.
It is safest to assume that your internet service provider does NOT provide any kind of firewall, so make sure you have the right software to protect yourself.
Types of firewalls:
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 8, Windows 7 and Vista, the Firewall defaults to active, so you do not need to 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 their IT infrastructure. Your internal or external IT support resource will be able to recommend, source, install and configure the most suitable one for your business needs.
Check if your Windows Firewall is switched on
In Windows 8 and Windows 7, 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.
In Windows XP, go to Control Panel, select Security Center. The Windows Firewall state is indicated.
Advantages of a software firewall:
A hardware firewall sits between your computer and the Internet, while a software firewall sits between your computer and the network. If other computers on your network become infected, the software firewall can protect your computer from them.
Software firewalls allow you to easily control network access on a per-application basis. In addition to controlling incoming traffic, a software firewall can prompt you when an application on your computer wants to connect to the Internet and allow you to prevent the application from connecting to the network. This feature is easy to use with a third-party firewall, but you can also prevent applications from connecting to the Internet with the Windows firewall.
Advantages of a hardware firewall:
A hardware firewall sits apart from your computer – if your computer becomes infected with a worm, that worm could disable your software firewall. However, that worm couldn’t disable your hardware firewall.
Hardware firewalls can provide centralized network management. If you run a large network, you can easily configure the firewall’s settings from a single device. This also prevents users from changing them on their computers.
Do You Need Both?
It’s important to use at least one type of a firewall – a hardware firewall (such as a router) or a software firewall. Routers and software firewalls overlap in some ways, but each provides unique benefits.
If you already have a router, leaving the Windows firewall enabled provides you with security benefits with no real performance cost. Therefore, it’s a good idea to run both.
You don’t necessarily have to install a third-party software firewall that replaces the built-in Windows firewall – but you can, if you want more features and you would like to have more configuration options.