Comment 13 for bug 1068756

Neil: the metadata is just one example (though that's not happening).

The firewall rule thing applies irrespective of the metadata. The cloud environment created requires only /128 addresses it knows about to be accessible, and firewalls everything else out. Reasons for this include prevention of spoofing of IP addresses on outbound traffic. We want each UEC image to come up with the IPv6 address(es) we have assigned, and not a random one in the same /64. This is not an unreasonable requirement. We would use DHCPv6 for this if it weren't for the fact that DHCPv6 is broken in different ways and has little support.

IPv6 *as designed* says RFC4941 SHOULD (RFC capitalisation) be turned off by default. So the argument that applications should be using it 'as designed' is bogus, as if it was deployed *as designed* (i.e. per the RFC) it would work. There would be no problem with (e.g.) Network Manager turning this on in a desktop environment.