Google is a search engine for human readable content. Shodan does the same for machine readable content.
You can:
- search for specific IP addresses, and it will show you the active ports, and running services.
- search for a specific response header in the set of countries
- browse through the screenshots of open VNC & RDP
- open webcams
- and more...
The free accounts can use any feature, but the list of results is limited. But if you really want to look under the deck of the internet, the subscription is worth it.
Well, for one they don't make it easy to be able to block them. For another, they basically advertise intrusion vectors to would-be nefarious actors.
Being connected online is advertising intrusion vectors to would-be nefarious actors