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The NAT lab wrote its generated node configs to one shared directory, unlike the static and firewall labs which already scope theirs by run. The directory is bind-mounted by compose and read back by the suite scripts after the containers are up, so two overlapping runs let the second run's generator overwrite the npubs the first is about to ping. Scope the directory with FIPS_CI_NAME_SUFFIX at all three places that have to agree: the generator's output path, the ten compose bind-mounts, and the CONFIG_DIR the suite scripts read back from. An unset suffix renders the plain path the lab has always used, so a bare invocation and the GitHub matrix are unaffected. The run teardown removes the per-run directory alongside the static and firewall ones, and the gitignore is widened to cover the suffixed form. Rendering the compose file with every profile and no suffix set reproduces today's exact ten paths; setting a suffix moves all ten. This lands on its own, ahead of the network and address work, so that a failure of the two-overlapping-runs acceptance test can be bisected between the config fix and the address conversion.
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 succeedssymmetric: both peers behind symmetric-style NAT, UDP traversal fails, TCP fallback succeedslan: 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
- uses UDP
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
iptablessetup
- NAT router image and
stun/- minimal STUN binding responder
relay/- local
strfryconfig
- local
scripts/generate-configs.sh- derives ephemeral identities and writes per-scenario FIPS configs
scripts/setup-topology.sh- injects and configures the NAT LAN
vethpairs in the container namespaces
- injects and configures the NAT LAN
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