Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Excellent book

Building Linux and OpenBSD Firewalls is truly a wonderful introductory guide into the world of network security. Written for the novice to intermediate user who is protecting their LAN or PC from on line attacks, I found the entire book interesting, relevant and surprisingly witty. (Example: In discussing how secure a network should be, the question arises: How do you make Windows remote control products secure? Answer: Drop them off the nearest cliff.)