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I am a unfortunate customer of a provider that uses a so-called DualStack Lite (I can't post more than two URLs - check Wikipedia for detailed information on DualStack Lite). Short: My router can't be reached via ipv4 easily. After I've switched to the new provider (I didn't realize the consequences) my TOR relay quit working (it's still configured with ipv4-ports only, so it's clear why it can't work). This howto says that it's not yet possible to run a ipv6-only TOR relay.

  • I understand that I can't run the relay with the DualStack Lite natively (as opposed to the outlined workaround below) - is that correct?
  • Is it possible to use a service like this to work around the limitations and run a TOR relay?

I assume that the answer to the latter question will be no because - as I understand - my relay registers itself at some TOR database with an outgoing ipv4 address and the configured ipv4 ports. If using a ipv4 -> ipv6 portmapper, a specific URL is used - one the TOR relay doesn't know about. Thus I think it's not possible for other TOR clients/relays to connect to my TOR relay.

However, if the answer to the latter question indeed is yes, could someone provide some howto or more detailed information about how to configure that (I didn't find anyting yet)?

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    From the looks of it, your v4 traffic is going through NAT, which would mean you can't receive inbound v4 connections. Unless your ISP allows you to reserve some v4 accessible port, this won't work currently. v6 is still too much of a rarity and can segment the network (harm anonymity). – cacahuatl Dec 31 '16 at 17:12
  • Yes, my TOR relay is behind a NAT. I think that at least in Europe (we've got less IPv4 addresses per person then e.g. the US) ISPs slowly switch to IPv6-only routing (and provide a rather rudimentary IPv4 routing-support). While for most users that doesn't cause a problem, for TOR relays it apparently does. – radix Jan 2 '17 at 16:06
  • You can still contribute to the network by setting up an IPv6 bridge - which helps much to a censored user. – nobody Jun 18 '18 at 3:32
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You are right, it will not work. You need to have an ipv4 address. Only (full) dual-stack provides both ipv6 and ipv4.

DualStack Lite (very common in Germany) means you have only a native ipv6 address, although through your provider you can make outgoing ipv4 requests. The other server will see an ipv4 address and can respond to it.

The opposite is not true: You do not have a public ipv4 address, but only a public ipv6 address. That is why you can only receive incoming requests over ipv6. Because of this limitation, it is called "Lite".

Some provides in Germany allow new (ipv6 only) customers to get an ipv4 address, but it will cost extra (e.g., MNet charges around 5 Euro per month).

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