====== OpenSSL ======
Useful commands for OpenSSL
===== CRLs =====
[[https://langui.sh/2010/01/10/parsing-a-crl-with-openssl/|Parsing a CRL]]: ''openssl crl -inform DER -text -noout -in mycrl.crl''

===== PKCS12 =====
Reading a PKCS12 file: ''openssl pkcs12 -info -in some_file.p12''

===== X.509 =====
  * Parsing a PEM file: ''openssl x509 -text -in some_file -inform pem''
  * Download and parse certificate: ''echo | openssl s_client -starttls=smtp -connect some_domain.tld:25 2>/dev/null | openssl x509 -text''

===== Connect with TLS =====
  * Connect to SMTP: ''openssl s_client -connect some_domain.tld:587 -starttls smtp''
  * Download certificate (HTTPS w/o SNI): ''openssl s_client -showcerts -connect some_domain.tld:443 </dev/null''
  * Download certificate (HTTPS w/ SNI): ''openssl s_client -showcerts -servername some_domain.tld -connect some_domain.tld:443 </dev/null''