Files
fips/testing/nat
Johnathan Corgan 242e619169 Stop two CI gates reporting someone else's failure as ours
Two unrelated harness defects with the same shape: the run's verdict
names something other than what actually went wrong.

The nostr publish/consume suite treats a dead relay as a product
failure. strfry is a third-party container and it has segfaulted
mid-run, twelve milliseconds after both nodes connected; everything
below that was a correct report of a dead relay, and the run failed on
the peer-count wait with the only evidence of the real cause sitting in
one container-log line ninety lines above the summary. Add a relay
verdict that states the relay's own condition — gone, not running,
restarted, or faulted per its log — and print it at the head of every
diagnostics dump, which is what every failure path already goes
through. A relay whose state or log cannot be read is reported as
unestablished rather than as healthy. The verdict does not decide the
run: a relay that faulted while the assertions still passed is noted
and left passing, since the suite proved what it set out to prove.

The setup-bucket refill test raced its own precondition. It delivered
exactly three forged setups against a 50/s refill and asserted one had
been refused, which holds only if all three finish inside one 20 ms
window; on a loaded runner the bucket refilled mid-loop, the third
setup was admitted, and the precondition failed on arrangement rather
than on behaviour. Under the CI retry policy that reports as green with
a flaky count, so nothing surfaced it. Drain against a 2/s refill,
which a delivery would have to take 500 ms to outrun, and deliver until
a refusal is actually observed rather than assuming three is enough,
with a cap that says what a runner slow enough to reach it means. The
refill half then waits out a full burst from empty.

(cherry picked from commit ec0fadfd136e0f6a64551fab61d042e486861842)
2026-08-25 20:50:12 +01:00
..
2026-07-27 17:57:21 +00:00

NAT Lab Harness

Real Docker-based NAT traversal integration tests for the mainline FIPS Nostr/STUN bootstrap path.

This harness spins up:

  • two FIPS nodes
  • a local Nostr relay
  • a local STUN server
  • one or two Linux router containers performing NAT with iptables

For the NAT scenarios, the node LAN interfaces are not attached to Docker bridge networks. The harness creates explicit veth pairs and moves them into the node and router namespaces after docker compose up so every packet must traverse the router namespace.

It covers three scenarios:

  • cone: both peers behind explicit namespace/veth full-cone emulation, UDP traversal succeeds
  • symmetric: both peers behind symmetric-style NAT, UDP traversal fails, TCP fallback succeeds
  • lan: both peers share a LAN subnet, LAN targets are preferred over reflexive addresses

NAT model notes

The harness does not rely on plain Docker MASQUERADE for the cone case.

  • cone
    • uses explicit full-cone emulation in the router namespace
    • outbound UDP is SNATed to the router WAN address while preserving the source port
    • inbound UDP to the router WAN address is DNATed back to the single LAN host regardless of remote source
  • symmetric
    • uses UDP MASQUERADE --random-fully
    • outbound mappings may be port-randomized and are only reopened by matching conntrack state

This distinction matters because plain MASQUERADE is convenient source NAT, but it does not by itself model the "accept from any remote once mapped" behavior expected from a full-cone NAT.

Prerequisites

  • Docker with Compose support
  • locally built fips-test:latest

Build the test image with:

./testing/scripts/build.sh

Run

Run all scenarios:

./testing/nat/scripts/nat-test.sh

Run one scenario:

./testing/nat/scripts/nat-test.sh cone
./testing/nat/scripts/nat-test.sh symmetric
./testing/nat/scripts/nat-test.sh lan

Layout

  • docker-compose.yml
    • relay/STUN/WAN topology plus container definitions
  • node/
    • node bootstrap wrapper that waits for the injected veth interface
  • router/
    • NAT router image and iptables setup
  • stun/
    • minimal STUN binding responder
  • relay/
    • local strfry config
  • scripts/generate-configs.sh
    • derives ephemeral identities and writes per-scenario FIPS configs
  • scripts/setup-topology.sh
    • injects and configures the NAT LAN veth pairs in the container namespaces
  • scripts/nat-test.sh
    • boots the lab, waits for convergence, and asserts the resulting path

Assertions

  • cone

    • both nodes connect
    • connected transport is UDP
    • active link remote addresses are on the WAN NAT subnet
  • symmetric

    • NAT bootstrap does not establish a UDP link
    • fallback converges
    • connected transport is TCP via router-published WAN addresses
  • lan

    • both nodes connect
    • connected transport is UDP
    • active link remote addresses stay on the shared LAN subnet