Can they grab local IPv6 addresses using this? While a huge number of computers are going to be on 192.168.0.1, their IPv6 address could actually be unique, making user fingerprinting easier.
Yes they can grab the IPv6 address but IPv6 has a privacy extension to cater for this. It will alter your local IPv6 address periodically. You could configure it to update every hour and effectively they'd be thinking you were a new PC on the network.
IPv4 you'd have a small range of IP addresses but with IPv6 you can have a different IPv6 address each hour if you so choose.
