Censys Overview

Censys is a public search engine that enables researchers to quickly ask questions about the hosts and networks that compose the Internet. Details on how Censys is architected and operated are available at About Censys. Instructions on how to use Censys are below.

Below are a series of example queries:

Hosts in 23.0.0.0/8 and 8.8.8.0/24:

IPv4

Telnet and FTP hosts in Germany:

IPv4

Popular websites without browser trusted certificates:

Websites

Popular websites that use Apache and support HTTPS:

Websites

Mozilla NSS trusted intermediate CAs:

Certificates

Industrial Control Systems in the United States:

IPv4

Hosts in ASes that contain word University:

IPv4

1000–1010th most popular site per Alexa Top Million:

Websites

Trusted certificates for Github.com:

Certificates