How to check a SSL certificate's expiry date

Published: Tuesday, 15 September 2020

For a certificate that is deployed, determine the host and port, then check it using openssl.

$ echo q | openssl s_client -connect ${HOST}:${PORT} | openssl x509 -text -dates | grep notAfter

where

  • ${HOST} is the hostname of the SSL service
  • ${PORT} is the port number of the SSL service. You can also use the service name, e.g. https