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I'm experimenting with network protocols a little bit and want to connect an IPv6 host from my IPv4-only internet connection using Teredo.

The computer is behind a NAT.

I tried different Teredo servers and I tried both Windows and Linux.

What I do is trying to establish a TCP connection (HTTP).

The result I observe in Wireshark is always the same:

  • My computer sends an initial ICMPv6 packet to the Teredo server
  • I receive the response - also an ICMPv6 packet
  • My computer sends multiple Ping (IPv6) packets
  • I never see an answer packet
  • After some time I get a time out
  • The "initial" ICMPv6 packet is repeated after some time and I see the answer.

Why is there no "ping" response from the IPv6 host (which are obviously neccessary for Teredo)?

--- Edit ---

After some more reading I can imagine that my Router is a "symmetric NAT" which is not supported by Teredo...

--- Edit 2 ---

... however I switched on "Port Forwarding" on my router for the UDP port that I use so a response should reach my computer even if it is sent from a different IPv4 address. And I switched off all firewalls.

Martin Rosenau
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1 Answers1

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Teredo is not the protocol you want to use for this. Its reliability is very unpredictable and Microsoft has plans to sunset its Teredo service. If you want to use IPv6 but your ISP does not support it (shame on them) then you should get a tunnel from i.e. Hurricane Electric or SixXS. Those tunnel servers are operated by people who care about the service and connectivity they deliver.

Sander Steffann
  • 4,802