Selection of a proper operating system is a very important task, and it can greatly influence the later stages of IT deployments. When making a choice on the operating system which will be used, it is very important to take the following points into consideration:

- familiarity with the operating system
- security of the operating system
- ease of upgrade
- application/package availability

There is a wide variety of operating systems out there, and it is up to the reader to select the preferred one. Still, since this is a Free Software cookbook, it will be primarily concentrated on GNU/Linux distributions, both server and client side. That said, pretty much any GNU/Linux distribution should be usable server-side, provided the packages are recent enough. On the other hand, the book will concentrate on using the Debian Squeeze GNU/Linux distribution server-side. Multiple client-side GNU/Linux distribution will be demonstrated in addition to this (for providing integration examples with the services).

When it comes down to deploying Debian Squeeze, it is highly advisable to create minimal setups through the network installation discs. The reminder of this book will also assume only the most basic tasks have been selected for the servers. Where appropriate, additional configuration notes will be mentioned together with samples (such as required firewall rules and the like). The minimal installation is best achieved by selecting the _SSH server_ and _Standard system utilities_ tasks during the _Software Selection_ phase.