application level firewalling in linux?(was:ipchains...masq..spyware)

[wsa <wsa@hotpop.com>]

HI,

Maybe in my original mail i wasn't very clear judging from the
responses i got...so i'll try one more time.

I wasn't asking what to do in windows...although i did mention
windows which probably made everyone run for the hills:)

My question was about linux and how to accomplish security
on application level, like what happens in windows with a personal
firewall.
Because i don't understand how i can achieve full security when opening
ports...like port 80 for the web or 110 and so on.
Cause as far as i can understand reading all the IPchains documentation
if i open that port in linux it wil be open for any application which
uses that port....and i can't specify that only mozzila or netscape
can use that port and any other app can use that port to transfer
information.

And if there is no need for security on application level why is that?

Cheers,
Willem