BRIEF CONTENTS -- CONTENTS IN DETAIL -- ACKNOWLEDGMENTS -- FOREWORD -- INTRODUCTION -- CARE AND FEEDING OF IPTABLES -- NETWORK LAYER ATTACKS AND DEFENSE -- TRANSPORT LAYER ATTACKS AND DEFENSE -- APPLICATION LAYER ATTACKS AND DEFENSE -- INTRODUCING PSAD: THE PORT SCAN ATTACK DETECTOR -- PSAD OPERATIONS: DETECTING SUSPICIOUS TRAFFIC -- ADVANCED PSAD TOPICS: FROM SIGNATURE MATCHING TO OS FINGERPRINTING -- ACTIVE RESPONSE WITH PSAD -- TRANSLATING SNORT RULES INTO IPTABLES RULES -- DEPLOYING FWSNORT -- COMBINING PSAD AND FWSNORT -- PORT KNOCKING VS . SINGLE PACKET AUTHORIZATION -- INTRODUCING FWKNOP -- VISUALIZING IPTABLES LOGS -- ATTACK SPOOFING -- A COMPLETE FWSNORT SCRIPT -- INDEX.