Red Hat Linux System Administration Handbook

Chapter 21. Connecting to the Internet

A case study in connecting a small business to the Internet

This chapter covers three items many small companies face—how to connect to the Internet with minimal cost, how to allow everyone in the company to use it, and how to protect it from crackers.

Overview

Firewalls are mainly designed to prevent unwanted activity on a network, so their basic function is to block connections from one network to another. In most applications, this would be from the Internet to your local network, and vice versa.

There are thousands of different firewall methodologies, but we will narrow our discussion in this chapter to ipfwadm. Let's assume that the local network is Ethernet with less than 254 machines, and connections to ...