Teredo IPv6 Address
From Teknologisk videncenter
Teredo
| IPv6 Address Type: | Teredo |
| Prefix: | 2001:0000::/32 |
| Local Routeable: | Yes |
| Global Routeable: | Yes |
| Global Unique: | Yes |
| Example: | 2001:0000:4136:e378:8000:63bf:3fff:fdd2 |
| IPv4 Equivalent: | No equivalent |
| Described in: | rfc4380 |
Explanation
This is a mapped address allowing IPv6 tunneling through IPv4 NATs. The address is formed using the Teredo prefix, the server’s unique IPv4 address, flags describing the type of NAT, the obfuscated client port and the client IPv4 address, which is probably a private address. It is possible to reverse the process and identify the IPv4 address of the relay server, which can then be looked up in the relevant RIR’s Whois database.
A Teredo tunnel is created on the Node that needs IPv6 connectivity through IPv4. Teredo works behind NAT/IPv4 because Teredo uses UDP/IPv4, which most NATs can forward properly.
Teredo was developed by Microsoft and there are several public Public Teredo Relay servers