The Windows Firewall is much like any other - it serves to block unsolicited traffic. It's based on XP's previous Internet Connection Firewall, and has been updated with more control options and the ability to start protecting the computer as soon as it boots up (previous versions allowed services to transmit without any checking during boot time). The Firewall dialog can be opened from within the Windows Security Centre, or by clicking on its icon in the Control Panel. When you do this, you'll see the following dialog;
Now, your first decision is really whether you want to use the firewall or not. If you already have a firewall program set up and configured on your machine, it's probably a good idea to stick with that and turn the Windows Firewall off. In fact, I was quite surprised when reading through the WF documentation to come across this;
"You do not have to use Windows Firewall - you can install and run any firewall that you choose. Evaluate the features of other firewalls and then decide which firewall best meets your needs. If you choose to install and run another firewall, turn off Windows Firewall."Looks like Microsoft are finally putting security ahead of monopoly - credit to them. Now, assuming you do want to use the Firewall - and it will suffice for a lot of users - there are still a few settings to adjust. Firstly, click on the "Exceptions" tab and ensure that the checkbox "Display a notification when Windows Firewall blocks a program" is ticked. This way, if WF blocks a program you want to use (e.g., ICQ), a notification will pop up and you'll be able to add it to the list of exceptions. Similarly, if you know now of any programs or specific ports you want to be unblocked, you can add them to the exceptions list by clicking "Add Program…" or "Add Port…" respectively. Clicking on the "Advanced" tab will bring up a few more important options.
Here, you can control which network connections have the Windows Firewall applied to them (defaults to all connections). With a connection selected, clicking "Settings…" will allow you to add program and service exceptions for that specific connection, as well as controlling ICMP packet restrictions (see below).
Internet Control Message Protocol (ICMP) is one of the staples of internet communication. Providing services like ping, tracert, and source quenching, ICMP packets can be useful tools in internet communication and troubleshooting. By default, however, the Windows Firewall blocks all ICMP packet traffic from entering or leaving your computer. This would mean, for example, that others would be unable to ping your computer to determine connectivity. You can change this by clicking on the "Settings…" button in the ICMP section of the Advanced panel and selecting which ICMP services you wish to allow.
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