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feat: Let an egress shard translate the NAT64 Well-Known Prefix - #28
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Public DNS64 resolvers synthesize into the RFC 6052 Well-Known Prefix 64:ff9b::/96, but a shard translates only its Network-Specific Prefix, so clients using those resolvers blackhole. nat64Prefix is write-once, so add a separate opt-in rather than changing it. Key changes: - Add spec.translateWellKnownPrefix, a mutable boolean that additionally translates the WKP from the shard's IPv4 address; a CEL rule requires nat64Prefix when it is true - Add status.translatesWellKnownPrefix reporting what the datapath programs - Document that the WKP must not map non-global IPv4 (RFC 6052 3.1) and that disabling the flag blackholes already-resolved WKP destinations until DNS TTLs expire - Cover the rule and the toggle in the e2e CEL test and the JSON keys in unit tests
scotwells
approved these changes
Oct 4, 2026
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IPv6-only workloads that use a public DNS64 resolver get answers in the RFC 6052 Well-Known Prefix, which egress shards do not translate, so those connections blackhole. This adds an opt-in that lets a shard translate the Well-Known Prefix alongside its own NAT64 prefix, using the same IPv4 address. The opt-in is accepted only on shards that already do NAT64, and unlike the NAT64 prefix it can be turned off again, at the cost of blackholing destinations clients already resolved until their DNS TTLs expire. Status gains a matching field reporting whether the datapath is actually translating the Well-Known Prefix.
Test plan