Almost daily, reports about hacker attacks can be found in the media. Prominent attacks, such as the one on the German Bundestag, are just the tip of the iceberg. Thousands of companies in Germany are attacked every day, often for the purpose of industrial espionage. IT and system administrators today must continuously check the increasingly complex infrastructures for vulnerabilities and security gaps. Identifying weaknesses, testing for vulnerabilities, and closing gaps are essential administrative tasks today. Only in this way can one successfully protect against attacks. If you are also responsible for the security of a network, you must continuously check it for vulnerabilities. Experts refer to this as penetration testing. Your goal must be to stay one step ahead of potential hackers. This book provides guidance on how to achieve that.