Often *Nix (Linux or Unix) fans will hype the security of *Nix systems compared with Microsoft operating systems. However, Unix and Linux have their fair share of vulnerabilities and what really makes a secure system is an informed administrator. These books will help you discover where you're vulnerable and keep your *Nix system secure.

1. Linux Security Cookbook

This book is an excellent resource for users and administrators of Linux to help secure and monitor their systems. The Linux Security Cookbook provides a number of "recipes" you can follow to get the desired end result- a more secure system. It includes coverage of firewalls, permissions and authorization controls, intrusion detection and more. Linux users should read this book.
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2. Practical Unix & Internet Security - 3rd Edition


Practical Unix & Internet Security is one of the few "must-read" books that every Security Administrator should read. The 3rd Edition is updated to include newer technologies like LDAP, Samba and wireless technology. The book discusses aspects of good physical security as well as some of the legal issues and implications of a hacked system. The scripts and checklists are great tools.
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3. Hacking Linux Exposed - 2nd Edition

The Hacking Exposed books have set the bar for this genre of security book. For those who administer Linux boxes this book provides an in-depth look at specific hacks and vulnerabilities unique to the Linux operating system and the accompanying fixes and workarounds to protect yourself. Hacking Exposed is a must-read for security- this book is a must-read for Linux security.
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4. Hack Proofing Sun Solaris 8


Hack Proofing Sun Solaris 8 provides an excellent introduction to securing a Solaris 8 system. It covers everything from securing the installation out of the box, to securely implementing Solaris 8 as a web server, email server, firewall or router. Although this book doesn't relate to the most current release of Solaris, most people trying to learn about securing Solaris will still benefit.
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5. Linux For Non-Geeks

Linux is a well-known operating system among the techno-geeks of the world, but it has also gained significant popularity among average users. Linux For Non-Geeks by Rickford Grant provides a glimpse at this powerful operating system and how to use it effectively without having to become a guru.
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