An excellent, if somewhat dated, book on system administration.
One of my professors recommended it back in my first year at university, and what I've learned from it has served me extremely well.
I decided to write this after seeing a review for it at Amazon.com, which criticized the network configuration portion of the text.
To this I must say two things- first of all, this text is supposed to just cover the essentials, if you wish to basically turn your box into a firewall or router- there are many texts and articles about it on-line.In addition to this most UNIX systems have excellent man pages and other help information, and on-line materials.
Oh, and it is much better to use a dedicated device for those purposes than some home-brew toy.
Well, if your projects is really critical that is.
And second - administration, be it system, application, or network, is a pretty overwhelming field.
Technologies change, new tools are added, and there is a difference between products by different vendors.
All that can't be covered in a single book!
However Frisch has made an excellent introductory text in the area, it will not turn you into an ace unix administrator over night, but it will show you the most important things about the various systems and the job, nay- art, in general.
The worst thing about the 3rd edition is that there isn't a 4th.