On 07/18/2013 09:09 PM, Brian E Carpenter wrote:
Wait... I had the impression that iff there was no other IPv6 connectivity, Teredo was used in older Windows because of the generic "prefer IPv6" rule. The default RFC 3484 table covers 6to4 but not Teredo.
AFAIK, every version of windows (i.e. Vista, 7, 8) that comes with Teredo also comes with a de-pref rule for it, not just "recent" versions.
Put another way, Teredo should never be preferred over IPv4, because all versions of Windows with Teredo use extended RFC 3484 rules.
Most of the Teredo activity we see is when IP addresses are used directly (i.e. no getaddrinfo). For example, BitTorrent connections where peers were looked up in DHT/PEX. In these cases, an IPv6 address will be connected to over Teredo if there's no other connectivity.
