A firewall is intended to save the computer which is connected to the internet from unauthorized access, just like a firewall in a building. Only known software (e.g. browser, e-mail, instant messanger) are granted access to the internet, every other attempted access is being stoped and indicated. Also the free firewall ZoneAlarm (siehe Downloads / Online is able to mask the computer as "not available".

As the access into foreign computers is no problem for many hackers today, the usage of a firewall is highly recommended.






Firewall im deutschen Lexikon
Firewall in het nederlandse encyclopedie