Troubleshooting Linux Firewalls - Book Review
By Ian Scott
I’ve been wanting to increase my knowledge of iptables and netfilter, the firewall system that comes with most Linux distributions. I knew some of the basics, but I decided it was time for me to increase my knowledge.
So I went looking for a book, I came across Troubleshooting Linux Firewalls, and at first, the title put me off. I wasn’t sure I was ready for something on troubleshooting. However, the description of the book intrigued me so I purchased it.
Troubleshooting Linux Firewalls is co-authored by brothers Michael and Scott Shinn. The Shinn brothers have been involved in network security for a very long time, and they can count the Whitehouse as one of their clients in the past. One of the brothers was also the co-founder of Plesk.
Although a discussion of firewalls can be a dry subject, the Shinn’s have managed to author a book that helps you understand not just the apples and oranges of firewalls, but concepts as well. Very seldom do they take anything for granted regarding your knowledge, and even a newcomer to Linux firewalls would benefit from reading this book and keeping it close by.
The book discusses a recommended troubleshooting methodology, something that many administrators overlook. I’ve seen others, and even myself, have tried to solve problems by the seat of our pants. It’s good to be reminded that a methodology that is habitually used will provide much better results in the long run. Regardless of what one is troubleshooting.
For TCP/IP amateurs like me, Troubleshooting Linux Firewalls provides a really good introduction and explained many concepts that previously I was uncomfortable with. As well, Shinn and Shinn point out that firewalls on their own are not the panacea of computer security. The book discusses many great tools, all of which are open source and freely available that one may use while managing the risk of having a server or computer connected to the Internet. In fact, a complete chapter is devoted to the Shinn’s “Collective Toolbox” along with some basic information on what the tools will do for you.
Being about iptables and netfilter, Michael and Stephen go through their own recommended iptables recipes, explaining what is going on and how it applies to what has been learned in previous chapters. After reading their recipes and thoughts on building a firewall, the reader is then provided with even more information and things to think about regarding e-mail, web servers, ftp and complete chapters dedicated to instant messaging services and VPNs.
One small criticism of the book: Throughout, the authors rarely take for granted your knowledge level, which means this book will be enjoyed by both newcomers to Linux firewalls and veterans. But when it came down to the scripts and recipes, there was no mention of where exactly to put them, and how to ensure these “scripts” run at boot up time. Many will know that the /etc/sysconfig/iptables file is read during boot up, but not everyone who reads this book might understand that. As well, some discussion of the iptables-config file would have been nice.
All in all though, I really benefited from reading this book. I plan on re-reading it, experimenting in my own lab, and carrying on my learning.
Read more in: Computer Security, Firewalls |