User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:81.0) Gecko/20100101 Firefox/81.0

Steps to reproduce:

N/A

Actual results:

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Expected results:

#1589781 introduced checking for NAT64 using the host resolver. Please add a preference so that the user can specify a NAT64 prefix which can be independent of the host resolver.

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.

(In reply to Chris Hills from comment #0)

#1589781 introduced checking for NAT64 using the host resolver. Please add a preference so that the user can specify a NAT64 prefix which can be independent of the host resolver.

Why is this needed?

This allows users to have control about how Firefox applies NAT64 using TRR, for instance, if the host network does not have NAT64 but you still want to use a NAT64 gateway.

I don't have time to work on this right now, but I'm happy to take patches for it.

Trr-only mode 3 rightly does not trust the system resolver and therefore disables the NAT64 checker. This would be useful to Trr mode 3 users.

Hi Chris Hills,

Does it serve your purpose if native IPv4 connection is preferred whenever possible over NAT64 prefixed addresses? That is, if IPv4 connection is unavailable, the NAT64 prefixed address will be used.

https://hg.mozilla.org/mozilla-central/rev/60bb38cedeb8

Thank you for working on this, and I apologize for my much delayed response. Ideally when a NAT64 prefix is entered, it should be used for all connections, not just when IPv4 is unavailable.