Create a strong CSR and private key
openssl req -new -nodes -newkey rsa:4096 -out server.crt -keyout server.key
Parsing out the data within a certificate
openssl asn1parse -in server.crt
Checking a certificate/key modulus to see if they correspond
openssl rsa -in server.key -modulus -noout | openssl md5
openssl x509 -in server.crt -modulus -noout | openssl md5
Convert a key from PEM -> DER
openssl rsa -inform PEM -in key.pem -outform DER -out keyout.der
Convert a key from DER -> PEM
openssl rsa -inform DER -in key.der -outform PEM -out keyout.pem
Remove the password from an encrypted private key
openssl rsa -in server.key -out server-nopass.key
Reviewing a detailed SSL connection
openssl s_client -connect host:port