Assumptions This Book Makes

We're really focused on improving the skill set of an established system administrator, so we aren't going to explain a lot of basics. We assume you can find your way to a command line and work your way through the filesystem with speed and grace. We expect that you already have a solid understanding of basic Unix permissions, are comfortable installing and configuring hardware and software, and so on.

If at any time you feel you're in over your head, fear not. Both operating systems have strong followings and easy to find documentation for all the basics. You can look at FAQs, HOWTOs, and handbooks online, or you can buy one of the many good references in print. The "Resources" section at the end of every chapter always lists good resources that provide additional coverage of relevant topics. In many cases, these additional resources provide the foundation in the technology you need to leverage the recommendations in this book.

The Internet is everywhere, and every administrator needs a basic understanding of local- and wide-area networking. We're not going to tell you what TCP/IP is, how DHCP works, or how to cable up your switches and hubs. We'll explain what you need to know when we get into a security topic that is rooted in the deep, dark corners of a protocol specification or some other relatively obscure topic. Network security and configuration are important, but we assume you've already got that under control.