Every server has a specific purpose in life, and FreeBSD and OpenBSD systems are ideal candidates for handling critical infrastructure services like DNS servers, firewalls, mail gateways, and web servers. Part II covers these deployments and how you can leverage specific BSD features to improve the security posture of the services you provide. We don’t tell you everything about deploying the specific service, however; just the extra options and special circumstances where you can take advantage of OpenBSD or FreeBSD. The goal of this section is to offer guidelines for securely deploying the software that will run critical services in your network.

With each of these critical network services, we take time to explain the kinds of risks you face, the sorts of attacks you might need to repel, and why you and your organization care about running the service securely. When we talk about installing and configuring software, though, we refer back to the general techniques and building blocks that we laid out in Part I. You’ll want to be at least passingly familiar with the techniques, because we combine them in interesting and sometimes subtle ways.