How to use Censys Search [IP address and server certificate search].

Access to Censys Search

Censys Search will be a website that allows users to research protocols available on a given server by global IP address and search for server certificates.

Access the following link.

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Censys Search

Hosts search by IP address

Enter the IP address and click “Search”.

Censys Search

Below is the results screen.

If any of the following server functions are present, the valid Protocol is displayed and the name of the Software that provides that Protocol (nginx, Apache HTTPD, linux, etc.) is displayed.

Example of Protocols

21/FTP , 25/SMTP , 80/HTTP , 110/POP3 , 143/IMAP , 443/HTTP , 465/SMTP , 587/SMTP , 993/IMAP , 995/POP3 , 10022/SSH

Censys Search IPアドレスからの検索結果

Certificate search by FQDN contained in the certificate

Enter the FQDN and select “Certificates” to start the search.

Censys Search Certificates

Below is the results screen.

Censys Search Certificates
Field NameDescription.
TagType/Status of Certificate
23 Expired => Expired
16 Previously Trusted => Previously Trusted Certificate
14 Leaf => Certificate
7 Never Trusted => Certificate issued by a Certificate Authority that is not currently trusted
IssuerCertification Authority Name
8 VeriSign, Inc.
6 SECOM Trust Systems CO.,LTD.
4 Japanese Government
CertificatesCertificate Subject
C=JP, ST=Tokyo, L=Chiyoda-ku, O=Ministry of Land\, Infrastructure\, Transport and Tourism,

Result screen after clicking on “Certificates”.
The blue mark to the left of the FQDN is the “Precert” (pre-certification) mark.

Censys Search Certificates

Censys Search Certificates