Files
fips/testing/firewall
Johnathan Corgan cbbdf2c13c Stop the firewall and ACL suites rebuilding an image their caller supplied
Both suites ran `docker compose up -d --build` unconditionally, and their
compose files carry both a build context and an image name, so the flag
rebuilt and retagged the shared test image from the shared build context on
every run. Their --skip-build flag did not cover it: it guarded only the
Rust build above. Under a harness that has already built the image and
handed it over, that rebuild can only replace the binaries under test with
whatever the shared context currently holds.

The nat scripts had the mirror-image problem. Their image guard built a
replacement whenever the image was missing, which is right by hand and
wrong under a harness: when the caller names an image it built, a miss
means something upstream is broken, and manufacturing a substitute hides
that. They now fail loudly in that case and keep building only on the hand
path. The mesh-lab guard reads the same variable and its build hint moves
to the script that still produces the shared tag.
2026-07-26 15:37:50 +00:00
..

Firewall Baseline Test

End-to-end exercise of the production fips0 nftables baseline at packaging/common/fips.nft. Closes the v0.3.0 audit gap that the default-deny + conntrack + drop-in semantics had no integration coverage.

What this exercises

The fips.nft baseline polices ONLY the fips0 mesh interface and implements default-deny inbound. This suite asserts the four behaviors documented in the file's header are actually true on a live mesh:

  • (a) Unallowed inbound on fips0 is dropped
  • (b) Outbound-initiated flows get their reply via the ct state established,related accept rule
  • (c) ICMPv6 echo-request is accepted (ping6 reachability)
  • (d) A drop-in .nft file under /etc/fips/fips.d/ adds an allowlisted port and that port is accepted

A drop-counter check after case (a) confirms the connection was actively DROP'd by the fips chain (not silently unrouted).

Topology

Two FIPS nodes peered over UDP on a Docker bridge network:

Container Hostname Firewall
fips-fw-container-a host-a none (probe)
fips-fw-container-b host-b fips.nft + drop-in

The bridge network requests no subnet, so docker assigns one from its own address pool and two concurrent runs never contend for a fixed range. No node's IPv4 address is therefore known before startup, and the generated peer stanzas address each other by docker hostname, resolved through the container's dnsmasq to docker's embedded DNS. The firewall assertions themselves are unaffected: they run over the fips0 overlay, whose addresses are derived from the node npubs.

node-b mounts the production packaging/common/fips.nft read-only at /etc/fips/fips.nft, plus a drop-in at /etc/fips/fips.d/services.nft containing tcp dport 22 accept. node-a is unfirewalled and serves as the probe origin.

Both containers run the unified test image's default mode, which starts dnsmasq + sshd (port 22) + iperf3 + python http.server on port 8000 + the FIPS daemon.

fips-firewall.service activation

The production unit's ExecStart is:

ExecStart=/usr/sbin/nft -f /etc/fips/fips.nft

The unified test image does not run systemd, so test.sh invokes the same nft -f command directly inside node-b after fips0 is up and peering has converged. The deb-install harness covers the systemd unit-enablement path under real systemd separately.

Run

Build the Linux binaries and test image:

./testing/scripts/build.sh --no-docker

Run the suite:

./testing/firewall/test.sh

test.sh regenerates fixtures automatically before starting Docker. Use --skip-build to reuse the existing release binaries. Use --keep-up to leave the containers running for inspection.

Expected output shape

=== Generating firewall fixtures
=== Starting firewall harness
=== Waiting for fips0 on both nodes
=== Waiting for peer convergence
=== Resolving fips0 addresses
  node-a: fd97:...
  node-b: fd97:...
=== Activating fips-firewall on fips-fw-container-b
PASS: fips-fw-container-b: fips.nft baseline + drop-in loaded
=== Case (c): ICMPv6 echo-request to firewalled node
PASS: (c) ICMPv6 ping node-a → node-b accepted
=== Case (a): unallowed inbound TCP/8000 from node-a → node-b
PASS: (a) inbound TCP/8000 dropped (curl rc=28, timed out as expected)
=== Case (b): node-b initiates outbound TCP, expects reply via conntrack
PASS: (b) outbound from node-b got HTTP 200 via conntrack reply path
=== Case (d): drop-in allowlisted TCP/22 from node-a → node-b
PASS: (d) drop-in allowlisted TCP/22 reachable
=== Drop counter incremented (case a should have ticked it)
PASS: drop counter = N (case a was actually dropped, not just unrouted)
=== Firewall integration test passed

Inspect the loaded ruleset

docker exec fips-fw-container-b nft list table inet fips

Stop and clean up

docker compose -f testing/firewall/docker-compose.yml down

Generated fixture location

testing/firewall/generated-configs/ (gitignored), or generated-configs<suffix>/ when FIPS_CI_NAME_SUFFIX is set, which is how concurrent runs keep their fixtures apart.