Shodan

Shodan is an internet intelligence search engine that indexes information about connected devices, services and infrastructure exposed on the public internet. Its data can help security researchers understand how technologies are deployed, identify publicly reachable systems and investigate patterns across internet infrastructure. Security teams can use Shodan for external exposure research and attack-surface discovery, while researchers and academics use it to study the changing composition of the internet. The platform provides searchable information such as service banners, ports, software characteristics and other observable metadata. Because the information represents publicly reachable systems, responsible use and authorization are important when applying the data to security assessments.