Most helpful positive review
39 of 41 people found the following review helpful
The current leader in the Snort IDS book arms race
on July 15, 2003
"Snort 2.0" offers content not found in other books on Snort, such as Tim Crothers' more generic "Implementing IDS" (4 stars) and Rafeeq Rehman's "Intrusion Detection with Snort." (3 stars) I've read the best IDS books, and used IDS technology, since 1998, and "Snort 2.0" is the first to give real insight into an IDS' inner workings. Thanks to the technical knowledge of the author team, "Snort 2.0" earns the reader's appreciation by explaining how and why the open source Snort IDS works its magic.
"Snort 2.0" starts well with a short history of Marty Roesch's favorite project, followed by solid explanations of the key elements of Snort's architecture in ch. 2. The actual workings of the Snort code is expanded upon in ch. 4 (modes), 5 (rules), and 6 (packet handling and preprocessors). One could read these sections and get a real sense of how the stream4 preprocessor works, for example. These sections are augmented by helpful tangents on compiling source code (ch. 3) and updates via CVS (ch. 9). This attention to detail and desire to include related information demonstrates a high level of commitment to the reader's education.
"Snort 2.0" has several technical errors or typos which prevented me from giving a 5 star review. p. 110's diagram of a TCP sessions should say "SYN, SYN-ACK, ACK", not "SYN, ACK, SYN-ACK". Later on that page, the author claims "The server replies with a SYN/ACK if the port is open, and a SYN/RST if the port is not listening." The correct closed response is "RST/ACK". p. 203 implies one can scan for open ports with the ACK flag set to evade stateless packet filters. This is wrong, as scanning with the ACK flag set only helps host discovery. I found the reprinting of multiple pages of C code unnecessary. I also wished the sections on building preprocessors had started from scratch, rather than explain an existing preprocessor.
Overall, I found "Snort 2.0" enlightening. The authors have a powerful understanding of the workings of Snort, and apply it in novel ways. "Policy-based IDS" in ch. 12 is one example, while the "rule categorization" chart in ch. 10 is another. Only the Wiley "Deploying Snort 2.0" book, due this fall, has a chance to displace "Snort 2.0" in the Snort-focused IDS book arena.