I'm thinking this might become pretty important with IPv6, no? My ISP advertises a prefix I can do SLAAC with, but they won't allow you to assign an arbitrary

I'm thinking this might become pretty important with IPv6, no? My ISP advertises a prefix I can do SLAAC with, but they won't allow you to assign an arbitrary address outside that prefix (which seems reasonable-ish for routing). GeoIP databases will have a harder time with IPv6, but if ISPs only use prefixes like this then it'll still be manageable..