Linux Security Cookbook [Paperback]

Chapter 1 - System Snapshots with Tripwire

I liked the discussion of Tripwire and its configuration options. The sections on "Ultra-Paranoid Integrity Checking" were great! A decent introduction to Tripwire and some of its features.

Chapter 2 - Firewalls with iptables and ipchains

The difference between "Drop versus Reject" targets was good. So many books have info on iptables, but none discusses these issues. Also the point made about dropping ICMP messages was good. Quick to learn and implement recipes presented in this chapter.

Chapter 3 - Restricting Access by Remote Users

Recipe 3.7 was very neat. Allowing users to access a service only by port-forwarding over ssh allows the administrator to restrict access by user names. A smart way of imposing restrictions!
Also, in recipe 3.9, I liked the authors' approach to finding if xinetd is compiled with libwrap support.

All recipes regarding tweaking xinetd were good. It isn't always possible to look at all the configurable options with xinetd, and the authors did a good job in mentioning a few useful options.

Chapter 4 - Authentication Techniques and Infrastructures

Quick tips with PAM, openssl and kerberos. I couldnt get some of the recipes to work on my machine, but got most openssl stuff to work.

Chapter 5 - Authorization Controls

I liked this chapter the best. The discussion on sudo was enlightening, and I was able to effectively tweak most recipes to my needs. The man page would never have provided me with such a good explanation. Thanks to the authors for this chapter.

Chapter 6 - Protecting Outgoing Network Connections

Two of these authors had written the snail book and I expected nothing less than a very useful recipe session on SSH. The most useful recipe here was setting up public key authentication between an openssh client and an ssh.com server and vice-versa. I had always wanted to do this but didnt have a clue until I read these recipes. All recipes have strong technical content and are well written. The recipe on running cron jobs with ssh was
amazing. The authors teach how to be creative, rather than merely
explaining facts and methodologies.

Chapter 7 - Protecting Files

I liked all recipes on GnuPG especially neat hacks like maintaining encrypted files with vim, encrypting backups etc..

Chapter 8 - Protecting Email

I tried out a few recipes and got them to work with my configuration. Pretty impressive stuff! The difference between SSL and STARTTLS daemons was very well explained. I havent seen a consolidated discussion on this topic thus far and was really happy to see things explained clearly in just one sidebar. I couldn't get the imap/ssl recipe working for my settings, inspite of spending quite some time. Perhaps a few screen-shots
made available via the website would've been of greatest help..

Chapter 9 - Testing and Monitoring

Recipes on Cracklib, using find for setuid/setgid files and the discussion on the 'find' command are very well written. Though this stuff has been mentioned in most security books/magazines, a consolidated treatment here is nice to note. nmap truly deserved the long section and I was able to learn a few facts I didnt know about nmap until now. The recipe on examining local network activities covered the best tools in business -
netstat, lsof and rpcinfo. Sniffing network traffic, using tcpdump, ethereal and dsniff provide a good refresher and ready-to-use recipes.

Overall, Linux Security Cookbook is a very useful book for quick
reference. It covers a wide range of security topics and issues related to not just Linux but most Unices. The recipes provided here are well written and ready to use. I have found many tips related to sudo, SSH, xinetd, encryption and network security extremely useful. Full credit to the authors for bringing out such a comprehensive book on Linux Security.

While many security books may waste the reader's time by spending hundreds of pages on introductory subjects; chapter 1 of the Linux Security Cookbook goes straight into using and configuring Tripwire.

The book then goes into fundamental topics such as firewalling with iptables/ipchains, authentication, access control, file control, email security and more.

If you are interested in Linux security, this is a well-written and well-organized book, filled with valuable and timely information.

This would be an excellent book for the new administrator to have right beside the keyboard, but it also will be useful for those with more experience. The recipes are concise, but complete: there is little wasted verbiage, yet you don't feel that anything important was left out.

As I said, I learned a few things. For example, I had never really looked at xinetd, assuming that it was just a slightly polished up inetd with different configuration files. My failure to look below the surface (or even really read the man page) caused me to miss quite a bit, and this book was a wake-up for me on that.

Recommended, worth the money.