Someone

auth.backend               = "plain"
auth.backend.plain.userfile = "lighttpd.user"
# auth.backend.plain.groupfile = "lighttpd.group"

# auth.backend.ldap.hostname = "localhost"
# auth.backend.ldap.base-dn  = "dc=my-domain,dc=com"
# auth.backend.ldap.filter   = "(uid=$)"

 auth.require = ( "/" =>
                 (
                 "method"=>"plain",
                 "realm"=>"download",
                 "require" => "user=user"
                 )