When I wrote the original edition of this book, I included a discussion of IPFire in the Snort section. At that time, IPFire had Snort built into it. It was a neat idea because you had an edge firewall and an Intrusion Detection System (IDS) all in one handy package. But, in the summer of 2019, the IPFire folk replaced Snort with their own IPS. So, I've moved IPFire down here into its own section.
The difference between IDS and IPS is that an IDS informs you of problems, but doesn't block them. An IPS also blocks them.
If you think back to our discussion of firewalls in Chapter 3, Securing Your Server with a Firewall – Part 1, I completely glossed over any discussion of creating the Network Address Translation (NAT) rules that you would need in order to set up an edge or gateway type of firewall. That...