Birthday attack for random symmetric NATs:
- birthday.rs: open_acceptor_ports() opens N sockets, STUN-probes
each to learn external ports. generate_dialer_targets() builds
hit list (known ports first, then random fill). spray_dialer()
sprays QUIC connects with rate limiting, first success wins.
- Default: 32 acceptor ports, 128 dialer probes, 20ms interval
Signal coordination:
- HardNatBirthdayStart { acceptor_ports, external_ip } sent by
Acceptor when peer's HardNatProbe shows random/sequential NAT
- Relay forwards it like other call signals
- Desktop recv loop handles and logs it
Hybrid waterfall integration:
- On receiving HardNatProbe with non-cone allocation, Acceptor
auto-opens birthday ports and sends BirthdayStart
- Sockets kept alive 10s for NAT mapping persistence
- Dialer spray integration into race() pending (needs transport
hot-swap for background upgrade)
6 new tests, 599 total, 0 regressions.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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