Concerning my opinion, you'd better have dedicated machine/gateway for firewall purposes, especially if a significant traffic is the case. Such a multihomed firewall can be configured VERY flexible and will satisfy classical scheme with DMZ (demilitarized zone). Or you can make one of the servers to function as a firewall in addition to its own functions. (It is not preferable though)
> so my question is: Can I install a Firewall on each of my Debian > Boxes to filter/block incoming and outgoing Network Traffic ? Of course you can! :) But it is not such a common approach - to make three configs instead of one. :) And yeah, there was a big discussion on the topic of the firewalling schemes on this list at second half of August. You can check the archive.
