I'm using an opensource library which lets you listen on a port of your choice for an image transfer protocol. I don't know any of the lower level details.
Administrators usually keep port 80 open (this is the http port right?) - is it possible to have an application listen on port 80? I don't know much about this but I would imagine the app expecting stuff based on this special image transfer protocol would get confused about stuff it was getting from web requests of some sort... anyway just some general info would be great,