Syngress Publishing has published a book on Ethereal called Nessus, Snort, & Ethereal Power Tools. It is written by Gilbert Ramirez, Brian Caswell, and Noam Rathaus.

If you have Snort, Nessus, and Ethereal up and running and now you're ready to customize, code, and torque these tools to their fullest potential, then this book is for you.

Table of Contents

1. The Inner Workings of NASL (Nessus Attack Scripting Language)
2. Debugging NASLs
3. Extensions and Custom Tests
4. Understanding the Extended Capabilities of the Nessus Environment
5. Analyzing GetFileVersion and MySQL Passwordless Test
6. Automating the Creation of NASLs
7. The Inner Workings of Snort
8. Snort Rules
9. Plugins and Preprocessors
10. Modifying Snort
11. Capture File Formats
12. Protocol Dissectors
13. Reporting from Ethereal

• Appendix A: Host Integrity Monitoring Using Osiris and Samhain

Excerpts from the book are available at the Publications link on the Ethereal web site.