I've set up an OS X Server, and I'm now trying to make its services available from outside my local network. From inside the LAN, the iCal service works fine when I add an 'OS X Server Account' via 'Internet Accounts' in System Preferences.
When I attempt to connect from the outside, it tells me it is
Unable to verify user credentials. The server is behind a firewall, so I've forwarded numerous ports in an attempt to get it to work. Initially I only added 8008 and 8443, as they are used for the iCal services, but as that did not work I attempted to forward other ports that might be relevant (based on their description in this list). This has not let me to any success, however.
What ports do I need to forward for the OS X Server Accounts to be available? The server is running Open Directory, so I'm assuming that the services rely on Kerberos for authentication? Is Bonjour relevant for this scenario, since I already know the IP I'll be connecting to?
Note: I'm not talking about Network Accounts, and have no intentions of logging in to network accounts remotely.