The Book of PF: A No-Nonsense Guide to the OpenBSD Firewall
Peter N. M. Hansteen
Time Management for System Administrators
Thomas A. Limoncelli
A Game as Old as Empire: The Secret World of Economic Hit Men ...
Steven Hiatt; John Perkins
The Linux Programming Interface
Michael Kerrisk
Nginx: From Beginner to Pro
Rahul Soni