As Kazaa, Napster, Groove, and other protocols have demonstrated, its quite easy to create peer-to-peer applications without either expensive external infrastructure or fixed, unique IP addresses.
These protocols require that at least one side in each transfer is capable of receiving inbound sessions. This can work if the user has a NAT and configures it such that inbound sessions are forwarded appropriately, but it can NOT work if the NATting is done by a service provider of some kind without any way for the user to configure this NAT box.
The scalability of
these protocols has threatened the Music and Movie Industries--and thats
really something. I wouldn't have thought such a thing possible ten years
ago.
So what else is new. In Shakespeare's time there were people that went to plays, memorizing them for later copying and performing the play without paying the author. And remember these are the same people that thought the VCR would kill their business.