merge: testing → main (reconcile 2-week divergence)

decnet/templates/mqtt/Dockerfile

@@ -0,0 +1,24 @@
+ARG BASE_IMAGE=debian:bookworm-slim
+FROM ${BASE_IMAGE}
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    python3 \
+    && rm -rf /var/lib/apt/lists/*
+
+COPY syslog_bridge.py /opt/syslog_bridge.py
+COPY instance_seed.py /opt/instance_seed.py
+COPY server.py /opt/server.py
+COPY entrypoint.sh /entrypoint.sh
+RUN chmod +x /entrypoint.sh
+
+EXPOSE 1883
+RUN useradd -r -s /bin/false -d /opt logrelay \
+ && apt-get update && apt-get install -y --no-install-recommends libcap2-bin \
+ && rm -rf /var/lib/apt/lists/* \
+ && (find /usr/bin/ -maxdepth 1 -name 'python3*' -type f -exec setcap 'cap_net_bind_service+eip' {} \; 2>/dev/null || true)
+
+HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
+  CMD kill -0 1 || exit 1
+
+USER logrelay
+ENTRYPOINT ["/entrypoint.sh"]

decnet/templates/mqtt/entrypoint.sh

@@ -0,0 +1,3 @@
+#!/bin/bash
+set -e
+exec python3 /opt/server.py

decnet/templates/mqtt/instance_seed.py

@@ -0,0 +1,120 @@
+#!/usr/bin/env python3
+"""
+Per-instance stealth seeding for honeypot service templates.
+
+The whole decoy fleet looks identical to a scanner unless each decky
+diverges on the boring details: cluster UUIDs, auth salts, uptime, minor
+version strings, etc. This module derives a stable per-instance seed
+from NODE_NAME (+ optional INSTANCE_ID) and exposes helpers that return
+deterministic-per-decky-but-different-across-the-fleet values.
+
+Connection-time jitter is intentionally NOT seeded — two hits to the same
+decky should not replay the same latency curve.
+"""
+
+from __future__ import annotations
+
+import asyncio
+import hashlib
+import os
+import random
+import time
+import uuid
+from typing import Sequence, TypeVar
+
+T = TypeVar("T")
+
+_HOSTNAME = (
+    os.environ.get("NODE_NAME")
+    or os.environ.get("HOSTNAME")
+    or "decky"
+)
+_INSTANCE_ID = os.environ.get("INSTANCE_ID", "")
+_SEED_MATERIAL = f"{_HOSTNAME}:{_INSTANCE_ID}".encode()
+_SEED_INT = int.from_bytes(hashlib.sha256(_SEED_MATERIAL).digest()[:8], "big")
+
+#: Deterministic RNG seeded per decky — use for *persistent* choices
+#: (versions, UUIDs, stored credentials). Never use for timing.
+rng = random.Random(_SEED_INT)
+
+#: Process boot time — real uptime elapsed since container start.
+_PROCESS_START = time.time()
+
+#: Deterministic per-instance fake "has been up for this long at boot"
+#: offset, so every decky pretends to have a different history.
+_BOOT_OFFSET = rng.randint(3600, 45 * 86400)
+
+
+def hostname() -> str:
+    return _HOSTNAME
+
+
+def uptime_seconds() -> int:
+    """Monotonically increasing, unique per instance."""
+    return int(_BOOT_OFFSET + (time.time() - _PROCESS_START))
+
+
+def boot_epoch() -> int:
+    """Fake wall-clock boot time for this instance (seconds since epoch)."""
+    return int(time.time() - uptime_seconds())
+
+
+def instance_uuid(namespace: str = "") -> str:
+    """Deterministic UUID4-looking value for this instance+namespace."""
+    ns = uuid.UUID("00000000-0000-0000-0000-000000000000")
+    return str(uuid.uuid5(ns, f"{_HOSTNAME}:{namespace}"))
+
+
+def instance_hex(nbytes: int, namespace: str = "") -> str:
+    """Deterministic hex token of given byte length."""
+    material = f"{_HOSTNAME}:{namespace}".encode()
+    digest = hashlib.sha256(material).digest()
+    while len(digest) < nbytes:
+        digest += hashlib.sha256(digest).digest()
+    return digest[:nbytes].hex()
+
+
+def pick(choices: Sequence[T]) -> T:
+    """Deterministic choice from a sequence."""
+    return rng.choice(list(choices))
+
+
+def pick_weighted(choices: Sequence[tuple[T, float]]) -> T:
+    """Deterministic weighted choice. Input: [(item, weight), ...]."""
+    total = sum(w for _, w in choices)
+    r = rng.uniform(0, total)
+    acc = 0.0
+    for item, w in choices:
+        acc += w
+        if r <= acc:
+            return item
+    return choices[-1][0]
+
+
+def random_bytes(n: int, namespace: str = "") -> bytes:
+    """Deterministic per-instance byte string of length n."""
+    out = bytearray()
+    i = 0
+    while len(out) < n:
+        out.extend(
+            hashlib.sha256(f"{_HOSTNAME}:{namespace}:{i}".encode()).digest()
+        )
+        i += 1
+    return bytes(out[:n])
+
+
+def fresh_bytes(n: int) -> bytes:
+    """Non-deterministic random bytes — for per-connection nonces/salts."""
+    return os.urandom(n)
+
+
+async def jitter(min_ms: int = 5, max_ms: int = 120) -> None:
+    """Async response-time jitter. Uses unseeded RNG so timing varies
+    across connections to the same decky — seeded jitter would leak
+    predictability."""
+    await asyncio.sleep(random.uniform(min_ms, max_ms) / 1000.0)
+
+
+def jitter_sync(min_ms: int = 5, max_ms: int = 120) -> None:
+    """Blocking jitter for non-asyncio servers."""
+    time.sleep(random.uniform(min_ms, max_ms) / 1000.0)

decnet/templates/mqtt/server.py

@@ -0,0 +1,340 @@
+#!/usr/bin/env python3
+"""
+MQTT server (port 1883).
+Parses MQTT CONNECT packets, extracts client_id, etc.
+Responds with CONNACK.
+Supports dynamic topics and retained publishes.
+Logs PUBLISH commands sent by clients.
+"""
+
+import asyncio
+import json
+import os
+import random
+import struct
+
+import instance_seed as _seed
+from syslog_bridge import (
+    encode_secret,
+    forward_syslog,
+    syslog_line,
+    write_syslog_file,
+)
+
+NODE_NAME = os.environ.get("NODE_NAME", "mqtt-broker")
+SERVICE_NAME   = "mqtt"
+LOG_TARGET = os.environ.get("LOG_TARGET", "")
+PORT = int(os.environ.get("PORT", "1883"))
+
+# Default to auth-required. A broker that accepts literally anyone with any
+# client_id / username was realistic for devices on a flat OT LAN pre-2018,
+# but in 2024+ it's a tell. Operators who *want* the anonymous-broker decoy
+# still set MQTT_ACCEPT_ALL=1 explicitly.
+MQTT_ACCEPT_ALL = os.environ.get("MQTT_ACCEPT_ALL", "0") == "1"
+# Optional cred list (user:pass comma-separated). If set, only those combos
+# succeed even when ACCEPT_ALL is off — lets operators plant credential bait.
+_MQTT_CREDS: set[tuple[str, str]] = set()
+for combo in os.environ.get("MQTT_CREDS", "").split(","):
+    combo = combo.strip()
+    if ":" in combo:
+        u, _, p = combo.partition(":")
+        _MQTT_CREDS.add((u, p))
+
+_PERSONA_CHOICES = ["water_plant", "building_hvac", "solar_farm", "factory_line"]
+MQTT_PERSONA = os.environ.get("MQTT_PERSONA") or _seed.pick(_PERSONA_CHOICES)
+MQTT_CUSTOM_TOPICS = os.environ.get("MQTT_CUSTOM_TOPICS", "")
+
+# Fleet-diverse broker ID. Real mosquitto versions in the wild right now.
+_BROKER_VERSION = os.environ.get("MQTT_BROKER_VERSION") or _seed.pick([
+    "mosquitto version 1.6.9",
+    "mosquitto version 2.0.11",
+    "mosquitto version 2.0.15",
+    "mosquitto version 2.0.17",
+    "mosquitto version 2.0.18",
+    "HiveMQ CE 2024.4",
+    "EMQX 5.3.2",
+])
+
+_CONNACK_ACCEPTED = b"\x20\x02\x00\x00"
+_CONNACK_NOT_AUTH = b"\x20\x02\x00\x05"
+
+
+def _log(event_type: str, severity: int = 6, **kwargs) -> None:
+    line = syslog_line(SERVICE_NAME, NODE_NAME, event_type, severity, **kwargs)
+    write_syslog_file(line)
+    forward_syslog(line, LOG_TARGET)
+
+
+def _read_utf8(data: bytes, pos: int):
+    """Read MQTT UTF-8 string (2-byte length prefix). Returns (string, next_pos)."""
+    if pos + 2 > len(data):
+        return "", pos
+    length = struct.unpack(">H", data[pos:pos + 2])[0]
+    pos += 2
+    return data[pos:pos + length].decode(errors="replace"), pos + length
+
+
+def _parse_connect(payload: bytes):
+    pos = 0
+    proto_name, pos = _read_utf8(payload, pos)
+    if pos >= len(payload):
+        return {}, pos
+    _proto_level = payload[pos]
+    pos += 1
+    if pos >= len(payload):
+        return {}, pos
+    flags = payload[pos]
+    pos += 1
+    pos += 2  # Keep alive
+    client_id, pos = _read_utf8(payload, pos)
+    result = {"client_id": client_id, "proto": proto_name}
+    if flags & 0x04:
+        _, pos = _read_utf8(payload, pos)
+        _, pos = _read_utf8(payload, pos)
+    if flags & 0x80:
+        username, pos = _read_utf8(payload, pos)
+        result["username"] = username
+    if flags & 0x40:
+        password, pos = _read_utf8(payload, pos)
+        result["password"] = password
+    return result
+
+
+def _parse_subscribe(payload: bytes):
+    """Returns (packet_id, [(topic, qos), ...])"""
+    if len(payload) < 2:
+        return 0, []
+    pos = 0
+    packet_id = struct.unpack(">H", payload[pos:pos+2])[0]
+    pos += 2
+    topics = []
+    while pos < len(payload):
+        topic, pos = _read_utf8(payload, pos)
+        if pos >= len(payload):
+            break
+        qos = payload[pos] & 0x03
+        pos += 1
+        topics.append((topic, qos))
+    return packet_id, topics
+
+
+def _suback(packet_id: int, granted_qos: list[int]) -> bytes:
+    payload = struct.pack(">H", packet_id) + bytes(granted_qos)
+    return bytes([0x90, len(payload)]) + payload
+
+
+def _publish(topic: str, value: str, retain: bool = True) -> bytes:
+    topic_bytes = topic.encode()
+    topic_len   = struct.pack(">H", len(topic_bytes))
+    payload     = str(value).encode()
+    fixed = 0x31 if retain else 0x30
+    remaining = len(topic_len) + len(topic_bytes) + len(payload)
+
+    # variable length encoding
+    rem_bytes = []
+    while remaining > 0:
+        encoded = remaining % 128
+        remaining = remaining // 128
+        if remaining > 0:
+            encoded = encoded | 128
+        rem_bytes.append(encoded)
+    if not rem_bytes:
+        rem_bytes = [0]
+
+    return bytes([fixed]) + bytes(rem_bytes) + topic_len + topic_bytes + payload
+
+
+def _parse_publish(payload: bytes, qos: int):
+    pos = 0
+    topic, pos = _read_utf8(payload, pos)
+    packet_id = 0
+    if qos > 0:
+        if pos + 2 <= len(payload):
+            packet_id = struct.unpack(">H", payload[pos:pos+2])[0]
+            pos += 2
+    data = payload[pos:]
+    return topic, packet_id, data
+
+
+def _generate_topics() -> dict:
+    topics: dict = {}
+    if MQTT_CUSTOM_TOPICS:
+        try:
+            topics = json.loads(MQTT_CUSTOM_TOPICS)
+            return topics
+        except Exception as e:
+            _log("config_error", severity=4, error=str(e))
+
+    if MQTT_PERSONA == "water_plant":
+        site = _seed.pick(["north", "south", "east", "west", "plant-a", "plant-b"])
+        topics.update({
+            f"{site}/water/tank1/level": f"{random.uniform(60.0, 80.0):.1f}",
+            f"{site}/water/tank1/pressure": f"{random.uniform(2.5, 3.0):.2f}",
+            f"{site}/water/pump1/status": "RUNNING",
+            f"{site}/water/pump1/rpm": f"{int(random.uniform(1400, 1450))}",
+            f"{site}/water/pump2/status": "STANDBY",
+            f"{site}/water/chlorine/dosing": f"{random.uniform(1.1, 1.3):.1f}",
+            f"{site}/water/chlorine/residual": f"{random.uniform(0.7, 0.9):.1f}",
+            f"{site}/water/valve/inlet/state": "OPEN",
+            f"{site}/water/valve/drain/state": "CLOSED",
+            f"{site}/alarm/high_pressure": "0",
+            f"{site}/alarm/low_chlorine": "0",
+            f"{site}/alarm/pump_fault": "0",
+        })
+    elif MQTT_PERSONA == "building_hvac":
+        floor = _seed.rng.randint(1, 12)
+        for i in range(_seed.rng.randint(4, 10)):
+            topics[f"bldg/floor{floor}/zone{i}/temp"] = f"{random.uniform(20.0, 24.5):.1f}"
+            topics[f"bldg/floor{floor}/zone{i}/setpoint"] = f"{random.uniform(21.0, 23.0):.1f}"
+        topics[f"bldg/floor{floor}/ahu/status"] = _seed.pick(["RUNNING", "RUNNING", "IDLE"])
+    elif MQTT_PERSONA == "solar_farm":
+        for arr in range(1, _seed.rng.randint(4, 9)):
+            topics[f"solar/array{arr}/power_kw"] = f"{random.uniform(40.0, 180.0):.1f}"
+            topics[f"solar/array{arr}/irradiance"] = f"{random.uniform(500, 950):.0f}"
+    elif MQTT_PERSONA == "factory_line":
+        line = _seed.pick(["A", "B", "C"])
+        for m in range(1, _seed.rng.randint(3, 7)):
+            topics[f"line{line}/machine{m}/state"] = _seed.pick(["RUN", "RUN", "IDLE", "FAULT"])
+            topics[f"line{line}/machine{m}/cycle_count"] = str(_seed.rng.randint(1000, 999_999))
+    if not topics:
+        topics = {
+            "device/status": "online",
+            "device/uptime": str(_seed.uptime_seconds()),
+        }
+    # $SYS keys match every real broker.
+    topics["$SYS/broker/version"] = _BROKER_VERSION
+    topics["$SYS/broker/uptime"] = f"{_seed.uptime_seconds()} seconds"
+    topics["$SYS/broker/clients/connected"] = str(_seed.rng.randint(2, 24))
+    return topics
+
+
+class MQTTProtocol(asyncio.Protocol):
+    def __init__(self):
+        self._transport = None
+        self._peer = None
+        self._buf = b""
+        self._auth = False
+        self._topics = _generate_topics()
+
+    def connection_made(self, transport):
+        self._transport = transport
+        self._peer = transport.get_extra_info("peername", ("?", 0))
+        _log("connect", src=self._peer[0], src_port=self._peer[1])
+
+    def data_received(self, data):
+        self._buf += data
+        try:
+            self._process()
+        except Exception as e:
+            _log("protocol_error", severity=4, error=str(e))
+            if self._transport:
+                self._transport.close()
+
+    def _process(self):
+        while len(self._buf) >= 2:
+            pkt_byte = self._buf[0]
+            pkt_type = (pkt_byte >> 4) & 0x0f
+            flags = pkt_byte & 0x0f
+            qos = (flags >> 1) & 0x03
+
+            # Decode remaining length (variable-length encoding)
+            pos = 1
+            remaining = 0
+            multiplier = 1
+            while pos < len(self._buf):
+                if pos > 4:  # MQTT spec: max 4 bytes for remaining length
+                    self._transport.close()
+                    self._buf = b""
+                    return
+                byte = self._buf[pos]
+                remaining += (byte & 0x7f) * multiplier
+                multiplier *= 128
+                pos += 1
+                if not (byte & 0x80):
+                    break
+            else:
+                return  # incomplete length
+            if len(self._buf) < pos + remaining:
+                return  # incomplete payload
+            payload = self._buf[pos:pos + remaining]
+            self._buf = self._buf[pos + remaining:]
+
+            if pkt_type == 1:  # CONNECT
+                info = _parse_connect(payload)
+                # Migrate auth event to the universal credential SD shape
+                # so the ingester's native branch picks up the row. The
+                # legacy username/password keys are intentionally NOT
+                # forwarded — encode_secret() supplies secret_printable
+                # and secret_b64 in their place.
+                _user = info.get("username", "")
+                _password = info.get("password", "")
+                _passthrough = {k: v for k, v in info.items()
+                                if k not in ("username", "password")}
+                _log("auth", username=_user, principal=_user,
+                     **encode_secret(_password), **_passthrough)
+                # Decide connection: accept-all > cred list > deny.
+                cred = (info.get("username", ""), info.get("password", ""))
+                accepted = (
+                    MQTT_ACCEPT_ALL
+                    or (cred in _MQTT_CREDS if _MQTT_CREDS else False)
+                )
+                if accepted:
+                    self._auth = True
+                    self._transport.write(_CONNACK_ACCEPTED)
+                else:
+                    self._transport.write(_CONNACK_NOT_AUTH)
+                    self._transport.close()
+            elif pkt_type == 8:  # SUBSCRIBE
+                if not self._auth:
+                    self._transport.close()
+                    continue
+                packet_id, subs = _parse_subscribe(payload)
+                granted_qos = [1] * len(subs)  # grant QoS 1 for all
+                self._transport.write(_suback(packet_id, granted_qos))
+
+                # Immediately send retained publishes matching topics
+                for sub_topic, _ in subs:
+                    _log("subscribe", src=self._peer[0], topics=[sub_topic])
+                    for t, v in self._topics.items():
+                        # simple match: if topic ends with #, it matches prefix
+                        if sub_topic.endswith("#"):
+                            prefix = sub_topic[:-1]
+                            if t.startswith(prefix):
+                                self._transport.write(_publish(t, str(v)))
+                        elif sub_topic == t:
+                            self._transport.write(_publish(t, str(v)))
+
+            elif pkt_type == 3:  # PUBLISH
+                if not self._auth:
+                    self._transport.close()
+                    continue
+                topic, packet_id, data = _parse_publish(payload, qos)
+                # Attacker command received!
+                _log("publish", src=self._peer[0], topic=topic, payload=data.decode(errors="replace"))
+
+                if qos == 1:
+                    puback = bytes([0x40, 0x02]) + struct.pack(">H", packet_id)
+                    self._transport.write(puback)
+
+            elif pkt_type == 12:  # PINGREQ
+                self._transport.write(b"\xd0\x00")  # PINGRESP
+            elif pkt_type == 14:  # DISCONNECT
+                self._transport.close()
+            else:
+                _log("packet", src=self._peer[0], pkt_type=pkt_type)
+                self._transport.close()
+
+    def connection_lost(self, exc):
+        _log("disconnect", src=self._peer[0] if self._peer else "?")
+
+
+async def main():
+    _log("startup", msg=f"MQTT server starting as {NODE_NAME}")
+    loop = asyncio.get_running_loop()
+    server = await loop.create_server(MQTTProtocol, "0.0.0.0", PORT)  # nosec B104
+    async with server:
+        await server.serve_forever()
+
+
+if __name__ == "__main__":
+    asyncio.run(main())

decnet/templates/mqtt/syslog_bridge.py

@@ -0,0 +1,261 @@
+#!/usr/bin/env python3
+"""
+Shared RFC 5424 syslog helper used by service containers.
+
+Services call syslog_line() to format an RFC 5424 message, then
+write_syslog_file() to emit it to stdout — the container runtime
+captures it, and the host-side collector streams it into the log file.
+
+RFC 5424 structure:
+  <PRI>1 TIMESTAMP HOSTNAME APP-NAME PROCID MSGID [SD-ELEMENT] MSG
+
+Facility: local0 (16). SD element ID uses PEN 55555.
+"""
+
+import base64
+import re
+from datetime import datetime, timezone
+from typing import Any, Optional
+
+# ─── Constants ────────────────────────────────────────────────────────────────
+
+_FACILITY_LOCAL0 = 16
+_SD_ID = "relay@55555"
+_NILVALUE = "-"
+
+SEVERITY_EMERG   = 0
+SEVERITY_ALERT   = 1
+SEVERITY_CRIT    = 2
+SEVERITY_ERROR   = 3
+SEVERITY_WARNING = 4
+SEVERITY_NOTICE  = 5
+SEVERITY_INFO    = 6
+SEVERITY_DEBUG   = 7
+
+_MAX_HOSTNAME = 255
+_MAX_APPNAME  = 48
+_MAX_MSGID    = 32
+
+# ─── Formatter ────────────────────────────────────────────────────────────────
+
+def _sd_escape(value: str) -> str:
+    """Escape SD-PARAM-VALUE per RFC 5424 §6.3.3."""
+    return value.replace("\\", "\\\\").replace('"', '\\"').replace("]", "\\]")
+
+
+def _sd_element(fields: dict[str, Any]) -> str:
+    if not fields:
+        return _NILVALUE
+    params = " ".join(f'{k}="{_sd_escape(str(v))}"' for k, v in fields.items())
+    return f"[{_SD_ID} {params}]"
+
+
+def syslog_line(
+    service: str,
+    hostname: str,
+    event_type: str,
+    severity: int = SEVERITY_INFO,
+    timestamp: datetime | None = None,
+    msg: str | None = None,
+    **fields: Any,
+) -> str:
+    """
+    Return a single RFC 5424-compliant syslog line (no trailing newline).
+
+    Args:
+        service:    APP-NAME (e.g. "http", "mysql")
+        hostname:   HOSTNAME (node name)
+        event_type: MSGID    (e.g. "request", "login_attempt")
+        severity:   Syslog severity integer (default: INFO=6)
+        timestamp:  UTC datetime; defaults to now
+        msg:        Optional free-text MSG
+        **fields:   Encoded as structured data params
+    """
+    pri     = f"<{_FACILITY_LOCAL0 * 8 + severity}>"
+    ts      = (timestamp or datetime.now(timezone.utc)).isoformat()
+    host    = (hostname or _NILVALUE)[:_MAX_HOSTNAME]
+    appname = (service  or _NILVALUE)[:_MAX_APPNAME]
+    msgid   = (event_type or _NILVALUE)[:_MAX_MSGID]
+    sd      = _sd_element(fields)
+    message = f" {msg}" if msg else ""
+    return f"{pri}1 {ts} {host} {appname} {_NILVALUE} {msgid} {sd}{message}"
+
+
+def encode_secret(secret: str) -> dict[str, str]:
+    """Standardized credential-secret encoding for the universal SD-block shape.
+
+    Returns ``{'secret_printable': ..., 'secret_b64': ...}`` ready to spread
+    into a :func:`syslog_line` / ``_log`` call::
+
+        _log("auth_attempt", principal=user, **encode_secret(password))
+
+    ``secret_printable`` mirrors auth-helper.c's sd_escape: bytes outside
+    ``[0x20, 0x7f)`` collapse to ``'?'`` so the field is always parser-safe
+    RFC 5424 ASCII. ``secret_b64`` preserves the *original* utf-8 bytes —
+    NUL/0xff/control/non-utf8 sequences all survive losslessly, useful as
+    a fingerprinting signal even when the printable form sanitizes them.
+
+    The decnet web ingester's native-shape branch keys off ``secret_b64``
+    being present, so any service emitter calling this helper lands its
+    cred attempt directly in the :class:`Credential` table.
+    """
+    raw = secret.encode("utf-8", errors="replace")
+    printable = "".join(chr(b) if 0x20 <= b < 0x7f else "?" for b in raw)
+    return {
+        "secret_printable": printable,
+        "secret_b64": base64.b64encode(raw).decode("ascii"),
+    }
+
+
+_DIGEST_PARAM_RE = re.compile(r'(\w+)\s*=\s*"([^"]*)"|(\w+)\s*=\s*([^,\s]+)')
+
+
+def classify_authorization(header_value: Optional[str]) -> Optional[dict[str, Any]]:
+    """Parse an HTTP Authorization header value into Credential SD fields.
+
+    Returns a dict with the universal cred shape ready to spread into a
+    ``_log(...)`` call::
+
+        auth = request.headers.get("Authorization")
+        cred = classify_authorization(auth)
+        if cred:
+            _log("auth_attempt", **cred)
+
+    Recognised schemes:
+      * Basic — base64(user:pw); decoded → ``principal=user`` +
+        ``secret_kind="plaintext"`` + ``encode_secret(pw)``.
+      * Bearer / Token — opaque token; ``principal=None`` +
+        ``secret_kind="http_bearer"`` + ``encode_secret(token)``.
+      * Digest — ``principal=username`` from header +
+        ``secret_kind="http_digest_md5"`` + ``encode_secret(response)``.
+
+    Returns ``None`` for anything unrecognized (AWS4-HMAC-SHA256, NTLM,
+    Negotiate, …) — callers can still log the raw header value in the
+    ambient SD-block; we just don't know how to extract a hashable
+    secret from it.
+    """
+    if not header_value or not isinstance(header_value, str):
+        return None
+    parts = header_value.strip().split(None, 1)
+    if len(parts) < 2:
+        return None
+    scheme, rest = parts[0].lower(), parts[1].strip()
+
+    if scheme == "basic":
+        try:
+            decoded = base64.b64decode(rest, validate=True).decode("utf-8", errors="replace")
+        except (ValueError, base64.binascii.Error):
+            return None
+        if ":" not in decoded:
+            return None
+        user, _, pw = decoded.partition(":")
+        return {
+            "principal": user,
+            "secret_kind": "plaintext",
+            **encode_secret(pw),
+        }
+
+    if scheme in ("bearer", "token"):
+        return {
+            "principal": None,
+            "secret_kind": "http_bearer",
+            **encode_secret(rest),
+        }
+
+    if scheme == "digest":
+        params: dict[str, str] = {}
+        for m in _DIGEST_PARAM_RE.finditer(rest):
+            k = m.group(1) or m.group(3)
+            v = m.group(2) if m.group(2) is not None else m.group(4)
+            if k:
+                params[k.lower()] = v
+        response = params.get("response")
+        if not response:
+            return None
+        return {
+            "principal": params.get("username"),
+            "secret_kind": "http_digest_md5",
+            **encode_secret(response),
+        }
+
+    return None
+
+
+_FORM_PRINCIPAL_KEYS = (
+    "username", "user", "email", "login", "userid", "account",
+    "log",        # wp-login.php
+    "user_login", # WordPress alt
+    "uname",      # phpMyAdmin
+    "pma_username",
+)
+_FORM_SECRET_KEYS = (
+    "password", "pass", "pwd", "passwd", "passwort", "mot_de_passe",
+    "user_password",   # WordPress alt
+    "pma_password",    # phpMyAdmin
+)
+
+
+def extract_form_credentials(
+    body: Optional[str],
+    content_type: Optional[str],
+) -> Optional[dict[str, Any]]:
+    """Parse an `application/x-www-form-urlencoded` body for credentials.
+
+    Returns the universal cred SD shape ready to spread into a
+    ``_log(...)`` call when both a principal-shaped key and a secret-
+    shaped key are present in the body. Otherwise returns ``None``.
+
+    Field-name detection is case-insensitive and covers the most common
+    login-form variants (WordPress wp-login.php, phpMyAdmin, Joomla,
+    etc.). Add more entries to ``_FORM_PRINCIPAL_KEYS`` /
+    ``_FORM_SECRET_KEYS`` as new templates surface them.
+    """
+    if not body or not isinstance(content_type, str):
+        return None
+    if not content_type.lower().startswith("application/x-www-form-urlencoded"):
+        return None
+
+    fields: dict[str, str] = {}
+    for pair in body.split("&"):
+        if "=" not in pair:
+            continue
+        k, _, v = pair.partition("=")
+        # urllib decode without importing urllib at module scope (the
+        # template emitters are import-cost-sensitive). Inline the
+        # tiny percent-decode + plus-decode.
+        try:
+            from urllib.parse import unquote_plus
+            key = unquote_plus(k).lower()
+            val = unquote_plus(v)
+        except Exception:
+            continue
+        # First-wins so duplicate-key forms don't get clobbered.
+        fields.setdefault(key, val)
+
+    principal: Optional[str] = None
+    for k in _FORM_PRINCIPAL_KEYS:
+        if k in fields:
+            principal = fields[k]
+            break
+    secret: Optional[str] = None
+    for k in _FORM_SECRET_KEYS:
+        if k in fields:
+            secret = fields[k]
+            break
+    if secret is None:
+        return None
+    return {
+        "principal": principal,
+        "secret_kind": "plaintext",
+        **encode_secret(secret),
+    }
+
+
+def write_syslog_file(line: str) -> None:
+    """Emit a syslog line to stdout for container log capture."""
+    print(line, flush=True)
+
+
+def forward_syslog(line: str, log_target: str) -> None:
+    """No-op stub. TCP forwarding is handled by rsyslog, not by service containers."""
+    pass