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HellMOO cannot be crawled: it publishes a link-local AAAA beside a good A #186

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@HarryCordewener

Measured 2026-09-17. hellmoo.org:7777 has been in the registry since 2026-07-31 and has never been dialled once.

$ dig +short AAAA hellmoo.org
fe80::b4e2:2dff:fee5:d965
$ dig +short A hellmoo.org
207.135.97.187

fe80::/10 is link-local and is never valid in public DNS. Scope.IsGloballyRoutable refuses it, and §7.2 refuses the whole target on a mixed answer rather than picking the good address — deliberately, and the guard is right. The result is that a large, long-running MOO is permanently unlistable, and reads in the registry as a perfectly healthy target (see #185).

Not a bug in the guard. Picking the routable address out of a mixed answer is exactly the hole §7.2 exists to close, and it must not be reopened for one game.

Options, in the order I would try them:

  1. Tell the operator. Their AAAA breaks IPv6-preferring clients generally, not just us — this is a real bug on their side and the fix is theirs.
  2. Decide whether a link-local address in a mixed answer deserves different handling from a private one. fe80:: is unreachable without a scope id, so the SSRF argument that motivates the rule does not obviously apply to it. This is a security decision and wants its own thinking, not a patch.

Doing nothing is also a defensible answer — but it should be a decision, not the current situation, which is that nobody knew.

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