I am trying to find an easy way to share a folder over the internet (not within my home network) with a friend (who is also using a Mac). It is pretty large and therefore using online storage options such as dropbox is not an option for me. Is there an easy way to do this on Mountain Lion? I have looked online and there are some suggestions about using SFTP but I have no idea how to set that up so it can be accessed outside my network.