#Create SSL key and CSR (Certificate Sign Request) by req
$ openssl req -new -newkey rsa:2048 -nodes -keyout foo_server.key -out bar_server.csr
#Create SSL key and CSR by genrsa
$ openssl genrsa -aes128 -out foo_server.key 2048
$ openssl genrsa -des3 -out foo_server.key 2048
#if you don't need passphrase, leave encrypt blank