By Joshua Erdman
A firewall is as necessary for a company network as virus scanning. Unfortunately setting up firewalls requires much more attention to detail than installing a virus scanner on your PC.
Firewalls vary in levels of complexity and capability. The most basic firewall is using NAT or Network Address Translation in which all office computers communicate to the Internet via a single IP address (this is basic function of your DSL/Cable modem routers). Firewalls can get as complex as having Intrusion Detection, Audit Trails, and Packet Filtering... Definitely something that cannot be covered in one article! To make all this easy to swallow, we have written up a collection of articles revolving around the Firewall Breakdown where we briefly describe the levels of complexity.
First read our Firewall Breakdown article to decide the protection that you need, then refer below to our HOWTO articles.
Network Address Translation Firewall
Our article on Using a DSL or Cable Modem Router essentially accomplishes the most basic of firewalls. Using one of these routers is the easiest way to share a high speed Internet connection, gives you basic protection, and simple port forwarding.
Using packet filtering is a great way to be more specific on what your network users are allowed to access on the internet. Usually this type of firewall still requires network address translation because you do not want your desktop computers to use public Internet addresses. Our article on Cisco Access Control Lists can guide you with setting up the correct Packet Filtering Firewall. However we still need to write an article on Setting up Network Address Translation on a Cisco Router.
Article last reviewed: 05/03/2004