Shodan

Using Shodan to search for publicly indexed device information is legal, as the search engine only collects data from services that are openly responding on the internet. However, using information found through Shodan to access or exploit devices without authorization is illegal under computer crime laws such as the U.S. Computer Fraud and Abuse Act.

Shodan continuously scans the internet by connecting to IP addresses across various ports and recording the banner responses returned by services such as HTTP servers, SSH daemons, FTP servers, and industrial control systems. This banner data reveals device types, software versions, and configuration details that are publicly exposed.

Google and similar search engines index web page content visible to users, while Shodan indexes the underlying devices and services connected to the internet—including routers, webcams, databases, and industrial control systems. Shodan is often described as a search engine for the Internet of Things and operational technology.

Shodan provides a free account tier that allows basic searching with limited results per query. Paid plans unlock full search results, API access, continuous monitoring alerts, and bulk data exports for professional security research.