Verify conection SSL with openssl

Valid ssl htpps from example

# openssl s_client -CApath /etc/ssl/certs/ -connect dm1.experian.com:443



Valid smtp with tls.

# openssl s_client -connect mail.example.com:25 -starttls smtp

# openssl s_client -connect mail.example.com:587 -starttls smtp -CApath /etc/ssl/certs/

# openssl s_client -connect mail.example.com:587 -starttls smtp -CAfile /etc/ssl/certs/CA.pem





Installing a CA
Copy your certificate in PEM format (the format that has ----BEGIN CERTIFICATE---- in it) into
/usr/local/share/ca-certificates and name it with a .crt file extension.
Then run:

#cp certificateCA.pem /usr/local/share/ca-certificates/certificateCA.crt

# sudo update-ca-certificates

output:

Updating certificates in /etc/ssl/certs... 1 added, 0 removed; done.
Running hooks in /etc/ca-certificates/update.d....done.