so I have an external server and an internal server connected via OpenVPN. I'd like to expose specific services on the internal server (say, apache) to the internet via the external server. I have a feeling this should be a fairly simple task involving either iptables, squid or NAT but I'm not exactly sure how to do this.
anyone have a quick thought or tutorial link? I'd even accept a book title for something related to complex Linux networking config.