Files
fips/testing/nat
Johnathan Corgan b459ca029b test(nat): dump diagnostics when a NAT lab ping fails
A failed data-plane ping was the one step in the NAT lab that reported
nothing. ping_peer sent ping6's output to /dev/null and the three
scenarios called it bare, so under `set -euo pipefail` a failure killed
the script with no message, without running the scenario's diagnostics
dump, and without tearing down; the next scenario's opening cleanup then
removed the failed containers and their logs. Two nat-symmetric failures
on the builder logged only the peer counts and FAIL, and the cause had to
be found by reproducing it locally.

ping_peer now captures ping6's output, names the source container, the
destination and the exit status on failure, and returns non-zero, matching
the assertion helpers above it. The six call sites wrap it in the same
`|| { dump_*_diagnostics; return 1; }` shape every other step uses. The
healthy path stays silent and the pass/fail verdict is unchanged.
2026-09-17 20:28:35 +00:00
..
2026-07-27 17:57:21 +00:00
2026-08-30 10:42:59 +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
  • scripts/nostr-relay-test.sh
    • exercises the Nostr overlay advert publish/consume round-trip, including rejection of a malformed advert event
  • scripts/stun-faults-test.sh
    • cycles the daemon through STUN drop, delay and outage faults and asserts graceful behavior at each step

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