ZoneAlarm-type firewall for Linux?

[Jason Spatafore]

I do know that there's a program out there named "AppArmor" that may
provide the protection you are looking for. It's designed to interact
directly with the kernel and allows you to define what processes can do
what...etc. You can set a default policy to disallow every process from
network access and then allow only certain processes to access the
network.

Anyway, take a look at it. It's named "AppArmor". I know it's available on
SuSE versions, not sure about others.