I happened to remember that there was a piece of information missing in the AppleTrans manual. I don't know how many people use Corpus Sharing, but there is an interesting feature in it.
In the Corpus Sharing view, when you click Publish button, AppleTrans will randomly select a port through which others connect to your corpora. And here is the trick. When you option click Publish button, AppleTrans always assign a fixed port number. And this port number is defined in the AppleTrans plist with "PrefsCorpusSharingNetServicePort" key.
So what's the deal? You now have an IP address and a fixed port for your host AppleTrans. If ever there is a way to make a connection to the host using this information, you may share your corpora over internet, out of the range that Bonjour covers. All right, let's discuss the rest next time.