openssl req -new -newkey rsa:2048 -nodes -keyout dev.ymeng.net.key -out dev.ymeng.net.csr
Common Name: DOMAIN-NAME
Organisation: Name of company
Organisation Unit: eg, web server 1
City: eg, Chengdu
State: Sichuan
Country: CN (ISO-3166-2, http://en.wikipedia.org/wiki/ISO_3166-1_alpha-2)
Generate CSR from existing certificate&key:
openssl x509 -x509toreq -in dev.ymeng.net.crt -out dev.ymeng.net.csr -signkey dev.ymeng.net.key