Networking → [ipv6] How to tell by looking at an IPv6 Address is native or tunneled

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And if tunneled, what kind of IPv4 to IPv6 tunnel?

Thank you

Just look at the prefix. 2002: is 6to4, and 2001:0: is Teredo.

Tunnels to a specific ISP don't follow a definite pattern, but you might be able to notice them using traceroute/tracepath, or by looking for an embedded hexadecimal IPv4 address.

You could also look at the v4 and v6 addresses and determine if they're being advertised by the same ASN.

Is "Teredo" the same as "6in4"?

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Is "Teredo" the same as "6in4"

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No. Teredo began as a Microsoft protocol but now is is an open standard. It encapsulates IPv6 datagrams in IPv4 UDP datagrams so is not really 6in4. In 6in4, the IPv4header is followed by the IPv6 packet being carried. No transport encapsulation is used. Teredo is much more complex then 6in4. Teredo is "friendly" with most types of IPv4 NAT. 6in4 is not NAT friendly.

No, 6in4 is the generic term for stuffing an IPv6 packet into an IPv4 packet using Protocol 41. The addresses can be anything that the endpoints agree upon, even beef:beef:beef:beef:beef:beef:beef:beef.

I asked because somebody once declared my 2001:470: tunnel as being Teredo, when it is really a Hurricane Electric 6in4.

That somebody probably failed to look beyond the first quad (16 bits).