This chapter discusses the details of configuring Unix for use in a firewall environment, building on the principles discussed in Chapter 10. You should be sure to read both chapters before attempting to build a bastion host. As usual, we use the word "Unix" for both Unix and Linux, except when we explicitly say otherwise.
It's impossible to give complete instructions on how to configure any given machine; the details vary greatly depending on what version of Unix you're running and exactly what you intend to do with the machine. This chapter is intended to give you an outline of what needs to be done, and how to figure out how to do it. For more complete configuration details, you will need to look at resources that are specific to your platform.