SSL Verification and Derivation Tips

Verify a private key

openssl rsa -noout -modulus -in <private-key-file>

Verify the public cert

openssl x509 -noout -in <certificate-file> -text

Verifying they match

The modulus of both should match (easiest to verify by hashing)

openssl x509 -noout -modulus -in <cert> | openssl md5
openssl rsa -noout -modulus -in <privatekey> | openssl md5

Checking Dates

openssl x509 -noout -dates -in <certificate-file>

Derivation Tips

Apache (2.4+)

Concatenate the cert followed by intermediate cert(s).

Set SSLCertificateFile and SSLCertificateKeyFile in the virtual host config


Concatenate the cert followed by intermediate cert(s)


Concatenate the cert, private key, followed by intermediate certs, and then optionally a dhparam output.

Dhparam output can be created by running: dhparam -out dhparam.pem 2048

The entry in haproxy will then look like:

bind    :443 ssl crt /path/to/<cert+privkey+intermediate> alpn h2,http/1.1

(Check for the best settings)