Web server behind a web server

I’ve acquired a new server which is to supply services to a certain group. On most cases, I would have used PREROUTE chain in my IPTABLES on my router for prerouting, based on a rule such as this: iptables -t nat -I PREROUTING -i <external_Interface_name> -p tcp -s <Some_IP_address> –dport 80 -j DNAT –to-destination <New_server_internal_IP>:80…