# openssl s_client

> OpenSSL command to create TLS client connections.
> More information: <https://www.openssl.org/docs/manmaster/man1/openssl-s_client.html>.

- Display the start and expiry dates for a domain's certificate:

`openssl s_client -connect {{host}}:{{port}} 2>/dev/null | openssl x509 -noout -dates`

- Display the certificate presented by an SSL/TLS server:

`openssl s_client -connect {{host}}:{{port}} </dev/null`

- Set the Server Name Indicator (SNI) when connecting to the SSL/TLS server:

`openssl s_client -connect {{host}}:{{port}} -servername {{hostname}}`

- Display the complete certificate chain of an HTTPS server:

`openssl s_client -connect {{host}}:443 -showcerts </dev/null`