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What is a Firewall?
A firewall essentially acts as a security guard for your computer. When you start up a new program or connect to the Internet, your firewall will ask you whether or not you wish to allow this software to have access to your computer. Once you have authorised a specific software application, the firewall can recall your choice each time you open it (this can be altered in your firewall’s settings if you change your mind).
With regards to the Internet, your firewall works in two ways: firstly it asks you if you wish to allow your Internet browser program (for example, “Microsoft Internet Explorer”, “Mozilla Firefox”, “Opera”, etc) access to your computer (this is necessary if you wish to go online, and you can almost always trust software from these companies), and secondly your firewall will block certain connections to your computer from outside sources. This latter action is best understood by considering the connection between the “World Wide Web” and your computer as lots of individual strands or fibres. Each strand (or “port”) is able to connect to the Internet when you go online. Your firewall will keep all of these ports closed, allowing access to one port at a time as you authorise your firewall to do so (computers without a firewall have all ports open, maximising vulnerability). Your firewall therefore blocks attempted access, preventing unwanted outside users or sources from entering, and seizing control of, your computer. You can view each notification of this scenario as the event happens if you wish, but it may become irritating after a while and you may choose to allow your firewall to work away in the background.
As the name suggests, a firewall exists to prevent unwanted intrusion from a potentially unsafe arena, which in most cases refers to the Internet. In essence, your firewall will monitor all incoming and outgoing Internet traffic, preventing unwanted access to your computer from applications that you have installed. Your firewall should also give you information about both the application attempting to connect to the Internet and the destination server the application is attempting to contact. Importantly, firewalls allow you to control which programs can and cannot access either the local network (your computer or network) or your Internet connection.
Alternative software
Operating systems, such as those found on PCs and Macs, usually come with a built-in firewall, but you may wish to shop around for independent firewall software with other features. If you’re finding Windows Firewall a little tricky, there are many free firewalls that offer a respectable, basic protection. ZoneLab’s ZoneAlarm is a tried and tested piece of free software praised for its simplicity. Alternative free software solutions include the award-winning Comodo program and Agnitum.
Why can’t I get online?
The firewall you are using will have settings that allow you to choose which programs can and can’t connect to the Internet. If you are using the standard Windows firewall, for example, the firewall is set to “on” by default. It can be set to “on”, “off”, or “on with exceptions”. It’s best to choose the latter option, and pick which programs you trust from the selections tab. If you’re a regular user of a web-browsing program (such as “Internet Explorer” or “Firefox”), an e-mail program (such as “Outlook” or “Mail”), a Voice over Internet Protocol (VoIP) or messaging program, or a file-sharing program, you should exclude them from your firewall’s watched list to save being prompted each time you open them. If you can’t get online to surf, it may be because your firewall is misconfigured.
On the other hand, as firewalls control inbound and outbound traffic, if you are connecting to the Internet in a public place, via wireless for example, you should select “on” with no exceptions, as on some firewalls, basic web-surfing will be permitted under this setting anyway; it’s the unsolicited inbound traffic you don’t want.
Changing your firewall settings
To change your firewall’s settings there should be an options tab within the program. If you are using Windows, go to the “Control Panel”, click “Windows Security Centre”, then “Firewall”, and choose on the “General” tab which programs can connect to your computer.
There is essentially no complete solution to the problem of computer viruses. However, ensuring that you have a good firewall installed, preferably in addition to standard anti-virus software, can lessen the danger. As more malicious software viruses are created by vindictive programmers (computer software developers), anti-virus and firewall creators try to keep up by offering regular updates for users. If you ensure that your firewall and anti-virus software is up to date, viruses can get through, but at least the risk is reduced. The trick is finding the right balance between protecting your computer and allowing friendly programs room to breathe.
