OpenSSL

Useful commands for OpenSSL

Parsing a CRL: openssl crl -inform DER -text -noout -in mycrl.crl

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

• 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 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