Every version of the AirPort Extreme and Express base stations (since
the first "snow" products, i.e. not the original "graphite") have
used endpoint-independent mapping and filtering for UDP
translations. They've also supported hairpinning. AirPort base
stations have always been designed expressly to be STUN-friendly.
Does that mean a "Cone NAT" or "Symmetric NAT" was supported in this
implementation.
I'm guessing by end-point independent this means symmetrical NAT.
Prior to RFC 4787, we called this "Unrestricted Cone NAT" behavior.
AirPort base stations aren't completely compliant with the BCP, but
they're better than a lot of competing products. Older base
stations didn't comply with REQ-13, for example. I'm not sure
whether AirPort Extreme always did or not. I'm pretty sure the
"snow" ones didn't. No version of AirPort base station fully
complies with REQ-4, REQ-7 or REQ-10.
--
james woodyatt <email@hidden>
member of technical staff, communications engineering
