Configuring Debian+Apache as an OWA Reverse Proxy in DMZ

If we have an Exchange installation and we want to publish OWA abroad, we should never open the ports directly to our Exchange, for this there are proxies located in the DMZ that will present us with our OWA. In this case we are going to set up a Reverse Proxy with DEBIAN and APACHE. To do this, we start from the fact that we have a debian installed in our DMZ with the port 443 of the WAN pointing at it and allowing the port to pass through 443 from our server to the LAN's Exchange CAS.