Port forwarding, I think?
I've been playing with this: http://www.panu.it/ardupower/.
It works fine when my iPhone is connected to the wifi network broadcast by the router to which the arduino (arduino ethernet shield) is connected. Is there a way of making it work across the internet, rather than just the local network? I imagine it has something to do with port forwarding, but I don't know much about it.
Thanks in advance.