Chapter 3. Into the Real World

Into the Real World

The previous chapter demonstrated the configuration for basic packet filtering on a single machine. In this chapter, we’ll build on that basic setup but move into more conventional territory: the packet-filtering gateway. Although most of the items in this chapter are potentially useful in a single-machine setup, our main focus is to set up a gateway that forwards a selection of network traffic and handles common network services for a basic local network.

A Simple Gateway

We’ll start with building what you probably associate with the term firewall: a machine that acts as a gateway for at least one other machine. In ...

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