When ip_no_pmtu_disc=0 the Linux kernel sets DF=1 on TCP packets and uses
IP ID=0 (RFC 6864). nmap's TI=Z fingerprint has no Windows match in its DB,
causing 91% confidence guesses of 'Linux 2.4/2.6 embedded' regardless of
TTL being 128. Setting ip_no_pmtu_disc=1 allows non-zero IP ID generation.
Trade-off: DF bit is not set on outgoing packets (slightly wrong for Windows)
but TI=Z is far more damaging to the spoof than losing DF accuracy.
Add tcp_timestamps, tcp_window_scaling, tcp_sack, tcp_ecn, ip_no_pmtu_disc,
and tcp_fin_timeout to every OS profile in OS_SYSCTLS.
All 6 are network-namespace-scoped and safe to set per-container without
--privileged. They directly influence nmap's OPS, WIN, ECN, and T2-T6
probe groups, making OS family detection significantly more convincing.
Key changes:
- tcp_timestamps=0 for windows/embedded/cisco (strongest Windows discriminator)
- tcp_ecn=2 for linux (ECN offer), 0 for all others
- tcp_sack=0 / tcp_window_scaling=0 for embedded/cisco
- ip_no_pmtu_disc=1 for embedded/cisco (DF bit ICMP behaviour)
- Expose _REQUIRED_SYSCTLS frozenset for completeness assertions
Tests: 88 new test cases across all OS families and composer integration.
Total suite: 812 passed.
- decnet/services/smtp_relay.py: open relay variant of smtp, same template
with SMTP_OPEN_RELAY=1 baked into the environment
- tests/service_testing/__init__.py: init so pytest discovers the subdirectory
Services now print RFC 5424 to stdout; Docker captures via json-file driver.
A new host-side collector (decnet.web.collector) streams docker logs from all
running decky service containers and writes RFC 5424 + parsed JSON to the host
log file. The existing ingester continues to tail the .json file unchanged.
rsyslog can consume the .log file independently — no DECNET involvement needed.
Removes: bind-mount volume injection, _LOG_NETWORK bridge, log_target config
field and --log-target CLI flag, TCP syslog forwarding from service templates.
- decnet/env.py: DECNET_JWT_SECRET and DECNET_ADMIN_PASSWORD are now
required env vars; startup raises ValueError if unset or set to a
known-bad default ("admin", "password", etc.)
- decnet/env.py: add DECNET_CORS_ORIGINS (comma-separated, defaults to
http://localhost:8080) replacing the previous allow_origins=["*"]
- decnet/web/api.py: use DECNET_CORS_ORIGINS and tighten allow_methods
and allow_headers to explicit lists
- tests/conftest.py: set required env vars at module level so test
collection works without real credentials
- tests/test_web_api.py, test_web_api_fuzz.py: use DECNET_ADMIN_PASSWORD
from env instead of hardcoded "admin"
Closes DEBT-001, DEBT-002, DEBT-004
