This is a very simplified guide only to Commercial Quality Free Firewalls.
A lot of us already know about these, but it's intended for those of us who don't.
I will post other Tips about other highly rated Free Security Programs depending on the responses here.
Before you decide, just bear in mind that no software suits everyone or every PC or OS. There are also personal likes, dislikes,foibles and resource usage issues that will no
doubtedly please or irk some people here. It's a guide only.
These
reviewed free utilities are all similarly rated and are a good contender for
equalling or even exceeding some of the top rated paid commercial software.
Most Firewalls are renowned for their annoying chatter. Those screens you see with warnings such as "Do you......." or "Firewall Needs.........." etc. This is what they are supposed to do. Some chatter may be just a bit too much for the average PC user to cope with and you may opt for a less aggressive, but less secure or less configurable Firewall. That's a personal thing that each of us needs to decide.
I simplified and reviewed 3 out of the top few contenders, tho there may be other similarly good or bad ones in your opinion.
Comodo Security Suite (includes optional Antivirus)32 bit and 64 bit bit compatible - Yes. Separate downloads.
HIPS protection - Yes
Ease of use - 5/10. Should improve after learning curve
Overall Protection - 9+/10 (user error not included)
Resource usage - One of the highest, but expected with this type of performance.
User configuration - 8/10 after learning curve.
Updates - Auto or Manual
Exceeds the performance requirements of paid commercial products.
Can be very daunting and extremely annoying for first time users.
An excellent and huge help file is included that should be read thoroughly.
Not recommended if you are annoyed easily or a bit lazy to read the seemingly initial constant chatter.
http://personalfirewall.comodo.com/download_firewall.htmlOnline-Armour Free32 bit and 64 bit compatible - Yes for Vista and W7. XP is 32bit only.
HIPS protection - Yes
Ease of use - 7/10 after learning curve.
Overall Protection - 9/10 (user error not included)
Resource
usage - A bit less than C
omodoUser configuration - 5/10. There's some questionable user configured disabling features
and software installer annoyances that may turn some users off this, otherwise it is excellent.
Updates - Auto or Manual
Similar to the performance requirements of paid commercial products but with some items locked out in the free version. Chatter is still annoying, but not as aggressive as C
omodoonline-armor-free.php">http://www.tallemu.com/products-online-armor-free.phpPC Tools Firewall Plus32 bit and 64 bit compatible - Yes. For Vista and W7. XP is 32 bit only.
HIPS protection - Yes
Ease of use - 6/10. Help is very sparse.
Overall protection - 8/10 (user error not included)
Resource
usage - Noticeably less than the above
User configuration - 4/10. The minimal help may be an issue and some items are only available in paid version. Ads in Free version can be annoying.
Updates - Auto or manual
Nearly as good as paid commercial products. Still has chatter you need to put up with.
http://www.pctools.com/firewall/Others you may consider : -
Outpost Firewall Free
Zone Alarm Free version
Inbuilt Windows 7 Firewall
PrivatefirewallSunbelt
Kerio Source information compiled from recent online reviews, specific software sites and public forums. 
LAN-based Failover: Send hello msg and start failover monitoring
Do you know the basic configuration steps in Nokia firewall
like(cisco show version,show run),
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