A very good overview of different OSS-tools for penetration testing, even if the quality of the book sometimes is a bit uneven (considering the number of authors, that is no surprise).

Of course, a book like this gets out of date very fast, but it still manages to age very well. Beware, that it is intended to the technical security crowd, so don't expect any relevant risk guidelines etc.

Still, an interesting book, if you're into the subject.