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IPv6 ICMPv6 accept

Firewall (nftables) · medium · solved in-browser (no VM needed) · 3 tiered hints

Author /etc/nftables.conf accepting icmpv6 (ipv6 neighbour discovery): a rule with `meta nfproto ipv6 icmpv6 type` ... accept or `ip6 nexthdr icmpv6 accept`. (Authored config, graded structurally — the engine isn't run here.)

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