Free Firewall

Firewalls protect your computer by limiting the ability of other people to access your computer. It monitors all traffic and allows or denies traffic according to the rules you set.

Sunbelt Kerio Personal Firewall

Kerio Personal Firewall is free for home use. It controls traffic from your computer to the Internet making it useful for blocking spyware, adware and other malware including keyloggers. It is a way to monitor all traffic from the Internet to your computer.

SoftPerfect Personal Firewall is a rule-based Windows network firewall that filters IP and non-IP traffic, supports configurations for multiple network adaptors, has a learning mode and comes with a set of predefined rules.

Agnitum Outpost Personal Firewall (Free Version) allows you to block traffic going in and out of your computer. It has the usual ability to hide your computer on the Internet (stealth mode), authenticate applications that run on your computer before allowing them to access the Internet (to make sure other programs have not modified it), filter viruses, worms and trojans from email, etc. This is a Windows firewall.

Look 'n' Stop Lite is a free firewall that filters inbound and outbound traffic from your computer. The Lite version is free for personal non-professional use, and is an early version of the commercial version. (Be sure you choose the appropriate link on the page to get the "Lite" version. The main version is not free.) This is a Windows firewall.

ZoneAlarm is an easy to use and free personal firewall that is used by many people on the Internet. The free version allows you to decide which applications you can allow to access the Internet, but does not allow you to block specific IP addresses. This is a Windows firewall.