Book excerpt: This book explains how to see one's own network through the eyes of an attacker, to understand their techniques and effectively protect against them. Through Python code samples the reader learns to code tools on subjects such as password sniffing, ARP poisoning, DNS spoofing, SQL injection, Google harvesting, Bluetooth and Wifi hacking. Furthermore the reader will be introduced to defense methods such as intrusion detection and prevention systems and log file analysis by diving into code. This book addresses interested Python programmers who want to learn about network coding and to administrators, who want to actively check the security of their systems and networks. The content should also be useful for white, gray and black hat hackers, who prefer Python for coding. You neither need deep knowledge on how computer networks are build up nor in programming.