Openssl command for certficates and key generation

 1) To connect secure port using SSL we can use the below command

openssl s_client -connect hostname/localhostip:portnumber

ex :  openssl s_client -connect 127.0.0.1:443

2) To show the certificate from website we can use the below command

openssl s_client -showcerts -connect 127.0.0.1:443

3) To Print Certificate we can use OpenSSL

echo | openssl s_client www.google.con -connectwww.google.con:443 2>dev/null | openssl x509 text

4) To covert pkcs12 to pem format we can use OpenSSL

openssl pkcs12 -in "certificate in pkcs12 format" -nodes -out "new_cert.pem"

5) to convert the certificate from crt to pem format

openssl x509 -in "cert.crt" -out "cert.pem"

6) to convert the certificate from cer to pem format

openssl x509 -in "cert.cer" -out "cert.pem"

7) to convert the certificate from pem to der format

openssl x509 -outform der -in "cert.pem" -out "cert.der"

8)  Openssl can used to generate public private key pair. Below uses pkcs8 format

openssl genrsa 4096 | openssl pkcs8 -topk8 -inform PEM -out rsa_key_4096.p8 -nocrypt

openssl rsa -in rsa_key_4096.p8 -pubout rsa_key_4096.pub

9)  Openssl can used to generate public private key pair. Below uses pkcs8 format