ArsTechnica: "Obtaining IPv4 addresses has been getting more difficult in recent years, as ARIN and the four other Regional Internet Registries (RIRs) keep tightening their policies and procedures. So with the well running dry, where can an intrepid IP address user turn to get that IPv4 fix? The black market, of course. Economists have been predicting the emergence of a black market for IPv4 addresses for some time. Some industry experts say it's already here. We say, not so fast."