openssl: request new/renew ssl certificate

• Generate certificate request
• Genreate certificate request and private key:

  openssl req -new -config csr.conf -keyout private.key -out server.csr

• Generate certificate request using existing private key:

  openssl req -new -config csr.conf -key private.key -out server.csr

• Submit the cerficate request file to be signed by CA