You may have noticed that vCloud Director uses 2 important IP addresses to provide public access to tenants/users. One is the well-known front-end VCD IP address which is access to web portal for managing the organization vDC (also known as HTTP access) and second one provides remote access to virtual console of VM which is in fact resided on ESXi server cluster (known as VRMC access), this latter one is sort of more back-end because it’s coming from ESXi server which never should be exposed to public! So, vCloud Director actually tunnels Remote Console communications between ESXi servers and users through a proxy agent on port 443. Apparently, the proxy service runs on vCloud Director machine. That’s why an extra IP is needed on vCloud Director. This IP address is also specified in initial setup but it can be changed later (of course everything can be changed!).
So, when you want to open up vCloud Director for public users, you should pay enough attention to VRMC IP address and port. If you have to do NAT through your firewall you should specify a different IP for VRMC and introduce the public IP/URL to vCloud Director in administration web panel. See the picture below:
Also, port 443 should be opened for this public IP on the firewall.
If you need more information about publicizing the whole vCloud Director, I found this excellent blog post about this topic, although it’s very useful for a general architecture of vCD deployment: