mirror of
https://github.com/jmcorgan/fips.git
synced 2026-07-30 19:46:15 +00:00
Johnathan Corgan
2fdc831ce3
The NAT lab was the last suite pinning fixed IPv4 subnets, so two overlapping runs collided on the wan and shared-lan bridges. Each run now claims a free /24 for each bridge, scanning candidates and advancing on an overlap while still failing fast on any other network-create error. The claim exports NAT_WAN_PREFIX and NAT_LAN_PREFIX, and every routable address in the compose file and the suite scripts derives from them, with defaults that render exactly what the lab used before. The router-side LANs are deliberately left pinned: they live inside per-container network namespaces, never become docker networks, and cannot collide. An external-network overlay lets the suites attach to the networks the run already claimed instead of creating their own. Two of the three suite scripts had no overlay hook, so they would have requested the claimed range a second time; both now have one. Host veth names are scoped by a short token rather than the full run id, which overruns the fifteen-character interface-name limit at the default run-id length, and the cleanup reaper's pattern is widened to match the new shape. Networks are released inline on every exit path rather than in a trap, since a trap written inside a shell function replaces the script-level handler and would disable the whole run's teardown.
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