This paper acts as a guide for penetration testers and security folks who want to use Shodan and helps them to understand how it can be used it for security auditing purposes.
You can download it from the following link: https://packetstormsecurity.com/files/download/127178/SHODAN_SAJAL_VERMA.pdf
Source: https://packetstormsecurity.com/files/127178/Search-Shodan-For-Fun-And-Profit.html