Firewalls Explained
What is a Firewall?
A firewall is a device designed to permit or deny network transmissions based upon a set of rules. A firewall is frequently used to protect networks from unauthorized access while permitting legitimate communications to pass. Basically a firewall is designed to keep the bad people out while allowing network traffic to function normally.
So what are the different types?
There are two main types of firewall, either hardware or software based.
Hardware Based
This is when you install the firewall software onto a separate computer and configure it so that it acts as a doorway into your network. For this configuration to work the firewall computer must be between the network and the internet and it must be fitted with two network cards. The advantage of this method is that any attacker would have to compromise the firewall computer before getting access to any other network resources. The firewall would also protect the entire network not just the computer it is installed on. The disadvantage is that you would require further hardware, however this can be mitigated as most hardware firewalls can run on low spec hardware. So if you have an old Pentium 3 computer sitting in the cupboard collecting dust go collect it and give it a new lease of life as a hardware firewall.
If you are looking for a hardware based firewall then I would recommend using Untangle Linux Firewall. This is open source software which while being easy to set up and configure is also very powerful. For instance it can also be configured as a VPN server allowing remote access to your network.
Software Based
This is when you install a piece of software onto the computer that you want to protect. The main advantages of this method are that it is usually easier to set up than a hardware based firewall and does not require any more hardware. The disadvantage of this approach is that the software will take up more system resources and the firewall will only protect the system it is installed on.
All modern operating systems come with software firewalls installed by default. However if you want to try another one then take a look at ZoneAlarm. I have been installing this on clients machines for the last 18 months and have been impressed. It is easy to set up and configure and should offer a sound solution to protecting your network.