So I want to share photos between 3 different accounts using iPhoto. However, everytime I click 'sharing' in the preferences, the system wants me to shut down the firewall (because the port 6770 (!?) needs to be accessed). I don't want to shut down the firewall. I tried enabling sharing iPhoto via. Bonjour option (enabling the port) but it still doesn't work. How do I get around this issue? It's absolutely essential the sharing works...