OpenSSL commands to check and verify your SSL certificate, key and CSR

Check a certificate:

Check a certificate and return information about it (signing authority, expiration date, etc.)

openssl x509 -in server.crt -text -noout

Check a key:

Check the SSL key and verify the consistency

openssl rsa -in server.key -check

Check a CSR:

Verify the CSR and print CSR data filled in when generating the CSR

openssl req -text -noout -verify -in server.csr

Verify a certificate and key matches

These two commands print out md5 checksums of the certificate and key; the checksums can be compared to verify that the certificate and key match.

openssl x509 -noout -modulus -in server.crt | openssl md5 

openssl rsa -noout -modulus -in server.key | openssl md5

from OpenSSL commands to check and verify your SSL certificate, key and CSR (ibm.com)