openssl genrsa -des3 -out server.key 2048
openssl req -new -key server.key -out server.csr
openssl x509 -req -days 365 -in server.csr -signkey server.key -out server.crt

openssl x509 -noout -modulus -in <file>.crt | openssl md5
openssl rsa -noout -modulus -in <file>.key | openssl md5

Si les 2 commandes ne génèrent pas le meme md5 c'est que le le .key n'est pas celui qui à servi pour générer le .crt.

openssl x509 -noout -text -in <file>.crt

openssl x509 -noout -text -in nnn -inform DER

openssl x509 -fingerprint -noout -in client.crt

openssl x509 -in input.crt -inform PEM –out output.crt -outform DER

openssl rsa -in input.key -inform PEM -out output.key -outform DER

openssl x509 -in input.crt -inform DER -out output.crt -outform PEM

openssl rsa -in input.key -inform DER -out output.key -outform PEM

openssl s_client -showcerts -connect www.google.com:443
openssl s_client -port 443 -host www.google.com

openssl s_client -connect 127.0.0.1:9999