This might seem a bit geeky but I’ll try to keep it simple, feel free to checkout Wiki for a more comprehensive description of Firewalls or check out http://www.firewallguide.com/software.htm to get your juices flowing.
Basically, Firewalls are classified as “Software Firewalls” and “Hardware Firewalls”.
Software Firewalls (a.k.a. Personal Firewalls)
These are basically software (programs / applications) that you install on your PC or each of your PCs. There are quite a few good ones but not all work as good as one would hope! There is a Firewall built into the Operating System (Windows) but In XP or earlier it isn’t much good but it’s better than nothing. However if you are running the spangly new Windows 7, the built-in firewall is brilliant – needs a bit of reading up on how to get the best of it but ultimately it might save you a few quid by not having to purchase a software firewall. There a few good FREE software firewalls and I’ll list these on another page, I still have reservations about using the “built-in” firewalls as I tend to be of the opinion that a dedicated software firewall vendor would be more expert at doing what they do best!
Basically a Hardware Firewall is a separate stand-alone “box” that is a dedicated Firewall – does nothing else. In principle it is a router and all network traffic going out to the Internet or coming in from the Internet has to pass through this box. Technically speaking, the “box” does indeed contain a “software Firewall” but the main difference is that the box is designed to only do the job of a firewall – nothing else. If you have read the Basic and Advanced security pages, you will realise that a “Hardware Firewall” is the “Border protection”. This means that it doesn’t matter how many PCs you have, all network traffic has to pass through this box and will be subject to “rules”. The rules will be based on the older” IP Chains” or more commonly the more modern “IP Tables” (sorry I’m getting geeky). Hardware Firewalls can cost hundreds of £s but there are a few FREE ones. The Free ones normally involve using an old PC that has 2 or more network cards and some version of Linux / Unix (Non Windows Operating system). All hardware Firewalls will need configuring, including the FREE ones and this is not a job for the feint hearted. Smoothwall is usually configured so that you don’t need to alter anything unless you have situations where you need to amend the settings but the on-line forums are friendly and very helpful.
If you already have a router (maybe a WiFi router supplied by your ISP,) Practically every router has the basic rudiments of a Firewall and will have at the least something called NAT. Basically NAT hides your IP address so that websites only know about your “public IP address”, your LAN then has a “private IP address”.
If your ISP has not supplied you with an “Internet Gateway router” or a “Broadband Router” (usually this is the case for Cable ISPs) you have a choice.
a. Use an old quiet PC and install an extra NIC then install Linux Smoothwall or similar, cost about £10 or less.
b. Purchase a “Broadband Router” if you are on Cable or an “ADSL Gateway” if you use the phone line. These range from about £15 upwards or a WiFi version from about £25. Spend a bit of time researching to get the best options that will fit your pocket – must have NAT, DHCP and ideally use SPI and content filtering.