The list of required ports for both a vCenter Server Appliance (VCSA) and Platform Services Controller (PSC) are pretty well documented here (6.5), here (6.0) and here (5.5) for customers who require this information to setup external connectivity within their networking infrastructure. Having said that, it is may not always be clear on what ports are actually opened as they will usually depend on the type of deployment and the services that are running. Instead, some customers have inquired about getting a list of all open ports directly from the VCSA/PSC to ensure they have the actual configuration which can be used to build firewall rules and/or for auditing purposes.
Today, the only method is to login directly into the VCSA/PSC via SSH (you could also use GuestOps API, so that SSH is NOT required) and fetching this information using iptables. Hopefully, in the future, this can be made available as part of the VAMI API since it already covers some basic inbound firewall rule capabilities. In the mean time, below are examples of how to get all the open ports for both VCSA/PSC
Run the following command to view all open ports on VCSA/PSC:
iptables -L port_filter -n --line-numbers
You will notice in the output above, there is also a chain number on the far left side which is associated with each rule. This chain number can be used to inspect the rule further and some rules include a nice alias to help you identify what the port might be used for.
For example, we can run the following to inspect chain rule #30 and find out this port is being used for syslog. If we want the port number, we simply add the -n option.
iptables -L port_filter 30
iptables -L port_filter 30 -n
Not all of the firewall rules have an alias name and even if they do, it still may not be apparent on what service is opening that particular port. We can actually look at the firewall rule definitions which are located under /etc/vmware/appliance/firewall and you will see a JSON file for each of the VCSA/PSC services that require firewall rules to be opened up. For a given port, you can just grep in this directory to identify the service that is requiring the port.
For example, if we take a look at the vmware-syslog, we see that it requires tcp/udp 514 and tcp 1514 under the "rules" array which defines the list of external ports open. You can ignore the internal ports as those are not exposed to the outside world but used by internal services. In case the services are still not clear, you can always reference the port number back to the documentation which I had linked above to get more details about the particular port.