Is ISPConfig designed with the intention that the admin panel on port 8080 is open to the internet? Every server I've put ISPConfig on has been behind a firewall and we only allow access to :8080 from a whitelist of our own management IPs. A scenario I am looking at won't allow for this so I am wondering if this is advisable.
Yes, ISPConfig GUI is intended to be used over the internet. Otherwise clients of a provider who uses ISPConfig to manage his servers won't be able to use it.