A technical post.
Shodan is a search engine that takes a distinct departure from most Internet search engines. Instead of searching through content intentionally served up and delivered to web browsers, Shodan allows us to search for Internet-connected devices. Created by John Matherly, Shodan uses distributed scanners throughout the world to randomly select target IP addresses and identify listening TCP and UDP ports. Listening ports are further enumerated to gather protocol banners, web pages, and other service data. All of this data is then added to an enormous, searchable database that describes the "what" of Internet devices.
Shodan's search feature is powerful, allowing us to specify generic terms such as "camera" or even a specific part number such as "WVC80N" and quickly identify the devices that match.
Beyond the web interface, Shodan offers a full-featured API and command-line tools to search and parse the Internet-device results. In this article we'll focus on using the web interface for effective device searches, as well as tips to use Shodan in your next penetration test.