Summary

Before you implement a firewall, first ask yourself what you are trying to defendand from whom. Firewalls are only one part of the overall security strategy, one tool among many that will help you defend your network, systems, and ultimately your business from threats. It is not a replacement for diligent planning, nor is it a security "silver bullet." Its purpose is, above all, to serve as a mechanism for compartmentalization. It cannot protect your systems from what you allow in.