{{tag>ssl cli}}

====== Openssl commands ======
===== Get cert expiration date from cert file =====

   openssl x509 -enddate -noout -in /etc/letsencrypt/live/example.com/cert.pem

===== Verfiy certs =====

   openssl verify -CAfile certs/rootCA.crt certs/client.crt

   openssl verify -CAfile certs/rootCA.crt certs/server.crt

===== Query site for expiration date =====

  echo | openssl s_client -servername example.com -connect example.com:443 2>/dev/null | openssl x509 -noout -dates -issuer
===== Determine a Key Size from  =====
==== Private Key ====

   openssl rsa -in secret.key -text -noout | grep "Private-Key"

==== Public Key ====


   openssl pkey -inform PEM -pubin -in pub.key -text -noout

===== Display the contents of a PEM formatted certificate =====

   openssl x509 -in example.com.pem -text

===== Test explicit TLS with FTPS server =====

   openssl s_client -starttls ftp -connect localhost:21

===== Get cert file from site =====

  openssl s_client -connect example.com:443 -servername example.com:443 < /dev/null | sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' | openssl x509 -in - -text -noout

<WRAP center round info 60%>
-connect can be the IP address of a server and is not necessarily the same as the -servername 
</WRAP>

===== Get OCSP stapling info =====

  echo QUIT | openssl s_client -servername www.example.com:443 -connect xx.xxx.xxx.xx:443 -status 2> /dev/null | grep -A 17 'OCSP response:' | grep -B 17 'Next Update'


===== Check if certificate is valid with private key =====
If you get an error like

  Oct 23 17:55:05 hpb01-rp nginx[2837]: nginx: [emerg] SSL_CTX_use_PrivateKey_file("/etc/nginx/ssl/some.key") failed (SSL: error:0B080074:x509 certificate routines:X509_check_private_key:key values mismatch)

Check certificate and private key

  openssl x509 -in /path/to/yourdomain.crt -noout -modulus | openssl sha1

  openssl rsa -in /path/to/your.key -noout -modulus | openssl sha1

You need to get the same sha sum from both commands.



===== Additional commands that can be used to inspect Certificates =====
 
The openssl x509 utility also allows you to extract specific pieces of information from the certificate file instead of the entire content of a certificate in text.  

  openssl x509 -in google.com-cert -noout -serial

  openssl x509 -in google.com-cert -noout -issuer

  openssl x509 -in google.com-cert -noout -dates

  openssl x509 -in google.com-cert -noout -subject

  openssl x509 -in google.com-cert -noout -pubkey

  openssl x509 -in google.com-cert -noout -modulus

  openssl x509 -in google.com-cert -noout -ocsp_uri
Note: Last command may not work in all versions of OpenSSL 

You can also mix and match arguments from the last step: 

  openssl x509 -in google.com-cert -noout -subject -issuer

  openssl x509 -in google.com-cert -noout -serial -dates

You can also request specific extensions from the certificate: 

  openssl x509 -in google.com-cert -noout -ext subjectAltName 

  openssl x509 -in google.com-cert -noout -ext basicConstraints

  openssl x509 -in google.com-cert -noout -ext crlDistributionPoints

  openssl x509 -in google.com-cert -noout -ext keyUsage

  openssl x509 -in google.com-cert -noout -ext extendedKeyUsage

  openssl x509 -in google.com-cert -noout -ext authorityInfoAccess

  openssl x509 -in google.com-cert -noout -ext subjectKeyIdentifier

  openssl x509 -in google.com-cert -noout -ext authorityKeyIdentifier


====== See also ======
  * [[wiki:creating_ca_and_signing_server_and_client_certs_with_openssl|Creating CA and signing server and client certs with openssl]]

====== References ======
  * https://www.xolphin.com/support/OpenSSL/Frequently_used_OpenSSL_Commands
  * https://www.namecheap.com/support/knowledgebase/article.aspx/9781/2238/nginx-ssl-error0b080074x509-certificate-routines-x509checkprivatekeykey-values-mismatch