Johnathan Corgan
700ac581ee
Case (a) sends an unallowed inbound request that the ruleset should drop, and accepted any non-zero curl status as proof. A drop produces no RST, so curl can only hit its deadline and exit 28; connection refused, an unroutable address or a missing listener all fail too, with different codes, and the check counted those as a blocked connection. Require 28 exactly, so the assertion distinguishes silently dropped from failed for some other reason. Confirmed against the harness: the real run returns 28. The baseline check matched `counter packets`, which any counter rule satisfies whatever its verdict, including one that accepts. Require the rendered drop rule instead. The drop-counter read had the same weakness plus a worse one: it took field three of the first line mentioning a counter, which is the packet count only when the line begins with `counter`. On a rule such as `tcp dport 9 counter packets 42 bytes 3000 drop` it printed the port number. That shape is reachable, because the shipped ruleset includes the operator drop-in directory ahead of the trailing default deny and a drop-in may add its own counted drop. Extract by position within the matched text, and take the last match rather than the first, since case (a) falls through to the default deny that the ruleset emits as the final rule. Note in place at the baseline check that it still only proves a counted drop rule exists somewhere in the table, not that it is the trailing one; asserting rule position is a larger change than this warrants. The sample output in the README is updated to the new wording.
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 acceptrule - (c) ICMPv6 echo-request is accepted (ping6 reachability)
- (d) A drop-in
.nftfile 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 | docker IPv4 | Firewall |
|---|---|---|---|
fips-fw-container-a |
host-a |
172.32.0.10 | none (probe) |
fips-fw-container-b |
host-b |
172.32.0.11 | fips.nft + drop-in |
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).