A good firewall is not a simple thing to engineer. It needs to outsmart every new hacker trick without bothering you or slowing you down.
An inbound firewall prevents Internet attacks such as hackers from coming into your computer. Any suspicious or unauthorized communications are filtered by the firewall. However, if these threats get through your firewall your personal data could then be transmitted back out to the hacker. To catch these thieves on their way out your firewall must be capable of automatically blocking unauthorized outbound communications - “outbound protection”.
Some firewalls don’t have what’s called “outbound protection”. That means they can’t control information that leaves your computer. This is risky, since hackers have ways around inbound firewalls. The ZoneAlarm outbound protection references our constantly updated database of trusted programs and program behavior—so the ZoneAlarm firewall can make security decisions safely and automatically.
At ZoneAlarm, we added outbound protection and then went beyond that to create the equivalent of guards who are trained to spot and stop suspicious behavior. We call this the OSFirewall, because it goes where dangerous programs go—to the operating system level. It monitors program installation, registry and file changes, keyboard and mouse code control, and over 40 other potentially dangerous behaviors.
Most firewalls with outbound protection generate a lot of "noise" -alerts asking you for input. Over the years we have developed ways to make our firewall as smart and quiet as possible. Our community-powered DefenseNet system constantly tracks the safety of millions of programs in real-time. Today, even the ZoneAlarm Free Firewall includes this automated program security, making it the quietest Free Firewall in the industry.
Note: OSFirewall is not included in the ZoneAlarm Free Firewall.