This entry is part of the series Ten things you can do to improve IT security and reliability without spending money

One of the key ways to keep your computers safe and secure is to make sure you are using a firewall to close out unwanted traffic.  I suspect many of you are thinking, “Yep, we’ve got that one covered, let’s move on.”

Hopefully, you do have this one covered, however, I think it’s worth a moment to point out a few things you should double-check.

By way of definition, the purpose of a firewall is to inspect network traffic and permit or deny passage based on a set of rules.  It is normally placed between a protected network  (like your home or office) and an unprotected network (like the internet) and acts like a gate to ensure that nothing private goes out and nothing malicious comes in.

Usually, a firewall is a dedicated appliance, or piece of equipment. A firewall can also be software, running on a computer. So the first thing you need to do is double-check to make sure the firewall is plugged in, turned on, or enabled. If you are using a software firewall, you need to check that it is turned on, and that you are set-up to receive regular software updates (I talked about the importance of applying patches and updates in a previous blog entry).  If you are running Windows Vista or Windows 7 operating system, you can check on the status of your updates using the Windows Action Center. In general, we recommend turning on Windows Firewall.

If you have technical resources available to you, it’s a good idea to have them periodically review the firewall logs and settings.  Specifically, they should check to ensure that no traffic is allowed from the outside (Internet) to the inside (home or office)—though there are some exceptions.  If you don’t have technical resources available to do this, Pragmatix engineers can usually run firewall scans at no cost.  (Send email to bill@pragmatix.com if you’d like a free scan.)

If you are running Windows 7 (which we recommend, by the way), the new Action Center (pictured below) is a perfect place to check these security settings.  It constantly monitors Windows firewall (and others), anti-virus software, internet explorer security settings, and network access settings.  If it detects a problem, it will notify you and provide links with instructions on how to fix it.

For personal use, there are a number of free firewall software products available on the market such as Comodo (http://personalfirewall.comodo.com/free-download.html?aid=350   ),  Outpost ( http://free.agnitum.com/   ), and  PCTools ( http://www.pctools.com/firewall/ ).

For small businesses, we’ve identified a few free firewall software products such as product name Private Firewall (http://download.cnet.com/Privatefirewall/3000-10435_4-10371057.html?tag=mncol