Check expiration date of a SSL certificate

You can check the expiration of the certificate (for example to help troubleshoot certificate issues).

1. Open a UNIX command line window.

2. Enter a query openssl s_client -servername <NAME> -connect <HOST:PORT> 2>/dev/null | openssl x509 -noout -dates.

The expiration date appears in the response as notAfter=<expiration_date>.

For example, if the HOSTis control.akamai.com, PORTis 443, using the openssl command, you can see the expiration date is Nov 21, 23:59:59 minutes in 2021.