A very well-known free firewall keeps your PC free from viruses and unknown threats. It defends hackers and spyware that steal your personal information and passwords. This program allows traffic to your PC that you initiate. Its nice Internet lock feature blocks all Internet traffic while your computer is unattended and it can be activated automatically with a screensaver or after a specified period of time. ZoneAlarm automatically makes your computer invisible to anyone on the Internet and consistently identifies and blocks unauthorized attempts. ZoneAlarm monitor all activity on your Computer and alerts you when a new application attempts to access the Internet.. The program includes four interlocking security services: Firewall, Zones, Internet Lock and application controls, which all collectively give you freedom of internet surfing without worrying about malware or hackers breaking into your Computer. ZoneAlarm is probably the easiest firewall to use and at the same time, very powerful. Its Game Mode lets you automatically allow or deny alerts when you are playing a video game. The program is Windows 2000, XP and Vista compatible.
Please visit ZoneAlarm Firewall Review for a detailed review on this product.
PC Tools Firewall effectively monitors applications that connect to network and blocks backdoors, key loggers, Trojans, viruses to enter your PC. The program provides automatic prevention against various different attacks and exploits. Experienced users have option to create their own advanced packet filtering rules, which include IPv6 support. This program expects you understand TCP, UDP, ICMP and a few other protocols but the wizard helps you adding a new filter in a few steps. PC Tools Firewall provides comprehensive network shielding to ensure maximum safety and it alerts you when a suspicious thing happens. The alerts are limited and easy to understand. The program is very easy to install, use, especially for beginners. PC Tools Firewall supports Windows 2000, XP and Vista. Do not forget to review PC Tools Internet Security 2009, though not free but one of the best firewall softwares.