One of the most popular services to shine light on and enumerate the darkest corners of the Internet is Shodan. It’s a portal-driven service through which subscribers can query its vast database of IP addresses, online applications and service banners that populate the Internet. Behind the scenes, Shodan’s multiple servers continually scan the Internet, enumerating and probing every device they encounter and recording the latest findings.
Source: Blocking Shodan
On one hand, you might empathize with many organizations on the receiving end of a Shodan scan. Their Internet-accessible systems are constantly probed, their services are enumerated, and every embarrassing misconfiguration or unpatched service is catalogued and could be used against them by evil hackers, researchers and journalists.