multi domain ssl csr

# cd /etc/ssl

# nano openssl.cnf

Look for  [ req ] section. Find add uncomment following line:

req_extensions = v3_req

In [ v3_req ] section, add following line:

subjectAltName = @alt_names

Finally add a new section called [ alt_names ] towards end of file listing all domain variation you are planning to use.

[ alt_names ]
DNS.1 = www.example.com
DNS.2 = example.com

# openssl req -nodes -sha256 -newkey rsa:2048 -keyout private/example.com.key -out example.com.csr -config openssl.cnf