use https://www.digicert.com/easy-csr/openssl.htm or edit script below to generate the private key and CSR

openssl req -new -newkey rsa:2048 -nodes -out star_server_com.csr -keyout star_server_com.key -subj "/C=US/ST=California/L=/O=/CN=*.server.com"

generate a 10 year wildcard selfsigned cert using

openssl x509 -req -days 3650 -in star_server_com.csr -signkey star_server_com.key -out star_server_com.crt