Links to free firewall software.

Zone Alarm

Zone Alarm is arguably the best free firewall, however it no longer supports Windows 98 or ME. However if you are running Windows 2000 or want to replace your XP firewall this would be a good and very cheap choice.

Agnitum Outpost

This is a free firewall that is suitable for users of Windows 98 and ME. Users of these operating systems shouldn't be online without it.

Sunbelt Kerio

This is a popular firewall but unfortunately doesn't support Windows 98 or ME. However if you have Windows 2000 this would be a good choice.

Comodo Free Firewall

This is a very popular firewall, some say it is better than Zone Alarm. While it is no use for Windows 98 or ME users, this would be a very good choice for Windows 2000 users or anyone wishing to replace their XP firewall.