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

decnet/templates/smtp/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 25 587
+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/smtp/entrypoint.sh

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

decnet/templates/smtp/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/smtp/server.py

@@ -0,0 +1,497 @@
+#!/usr/bin/env python3
+"""
+SMTP server — emulates a realistic ESMTP server (Postfix-style).
+
+Two modes of operation, controlled by SMTP_OPEN_RELAY:
+
+  SMTP_OPEN_RELAY=0 (default) — credential harvester
+    AUTH attempts are logged and rejected (535).
+    RCPT TO is rejected with 554 (relay denied) for all recipients.
+    This captures credential stuffing and scanning activity.
+
+  SMTP_OPEN_RELAY=1 — open relay bait
+    AUTH is accepted for any credentials (235).
+    RCPT TO is accepted for any domain (250).
+    DATA is fully buffered until CRLF.CRLF and acknowledged with a
+    queued-as message ID. Attractive to spam relay operators.
+
+The DATA state machine (and the 502-per-line bug) is fixed in both modes.
+"""
+
+import asyncio
+import base64
+import hashlib
+import json
+import os
+import random as _rand
+import re
+import time
+from datetime import datetime, timezone
+from email import message_from_bytes
+from email.header import decode_header, make_header
+from email.message import Message
+
+import instance_seed as _seed
+from syslog_bridge import (
+    SEVERITY_WARNING,
+    encode_secret,
+    forward_syslog,
+    syslog_line,
+    write_syslog_file,
+)
+
+NODE_NAME   = os.environ.get("NODE_NAME", "mailserver")
+SERVICE_NAME = "smtp"
+LOG_TARGET  = os.environ.get("LOG_TARGET", "")
+PORT        = int(os.environ.get("PORT", "25"))
+OPEN_RELAY  = os.environ.get("SMTP_OPEN_RELAY", "0").strip() == "1"
+
+# In open-relay mode, optionally restrict which creds succeed. Blank means
+# "accept anything". Format: "user1,user2,..." — any name not in the list
+# gets a 535 instead of 235, so the relay looks realistically selective.
+_AUTH_WHITELIST = {u.strip() for u in os.environ.get("SMTP_AUTH_WHITELIST", "").split(",") if u.strip()}
+
+# Open-relay filtering. Even compromised/misconfigured relays aren't pure
+# tarpits — Postfix rejects malformed addresses at RCPT time, and many drop
+# a small fraction of external recipients under greylisting or reputation
+# checks. Accepting literally every RCPT is a honeypot tell.
+_ADDR_RE = re.compile(r"^<?([^\s<>@]+)@([A-Za-z0-9.-]+\.[A-Za-z]{2,})>?$")
+_BLOCKED_TLDS = {"invalid", "test", "localhost", "local", "example"}
+_RCPT_DROP_RATE = float(os.environ.get("SMTP_RCPT_DROP_RATE", "0.08"))
+
+_SMTP_BANNER = os.environ.get("SMTP_BANNER", f"220 {NODE_NAME} ESMTP Postfix (Debian/GNU)")
+_SMTP_MTA    = os.environ.get("SMTP_MTA", NODE_NAME)
+
+# Full-message capture: bind-mounted quarantine dir (host path
+# /var/lib/decnet/artifacts/{decky}/smtp). When unset, capture is skipped —
+# the container still accepts mail, it just doesn't persist the body. Used by
+# tests and by deployments that don't want disk persistence.
+_QUARANTINE_DIR = os.environ.get("SMTP_QUARANTINE_DIR", "")
+# EHLO advertises SIZE 10240000 (10 MB). Cap the accumulator at the same
+# value so a crafted client can't OOM the container by streaming forever.
+_MAX_BODY_BYTES = int(os.environ.get("SMTP_MAX_BODY_BYTES", "10485760"))
+
+# Postfix's queue-ID character set (real one: excludes vowels and look-alikes
+# like 0/O, 1/I, so scanners that know Postfix's alphabet are satisfied).
+_QUEUE_CHARS = "BCDFGHJKLMNPQRSTVWXYZ23456789"
+_Q_BASE = len(_QUEUE_CHARS)
+
+
+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 _rand_msg_id() -> str:
+    """Postfix-style queue ID.
+
+    Real Postfix derives its short queue IDs from the message's arrival
+    microseconds, base-encoded with a vowel-free alphabet — so IDs are
+    monotonically increasing and visually distinctive. We encode the current
+    microsecond count with Postfix's actual character set, then append a
+    short per-instance suffix so two deckies never emit identical IDs at
+    the same instant.
+    """
+    us = int(time.time() * 1_000_000)
+    out: list[str] = []
+    while us and len(out) < 10:
+        us, r = divmod(us, _Q_BASE)
+        out.append(_QUEUE_CHARS[r])
+    base = "".join(reversed(out)) or _QUEUE_CHARS[0]
+    suffix_idx = _seed.rng.randint(0, _Q_BASE - 1)
+    return base + _QUEUE_CHARS[suffix_idx]
+
+
+def _decode_header(raw: str | None) -> str:
+    """Best-effort decode of an RFC 2047 encoded-word header to Unicode.
+
+    Returns "" for missing / undecodable values so callers can treat the
+    result as a plain string.
+    """
+    if not raw:
+        return ""
+    try:
+        return str(make_header(decode_header(raw)))
+    except Exception:
+        return raw
+# Stored_as format mirrors the SSH artifact convention so the existing
+# /api/v1/artifacts/{decky}/{stored_as} endpoint and its filename regex
+# accept SMTP drops unchanged: <iso_ts>_<sha12>_<basename>. The basename
+# always ends in .eml so operators can open it in any MUA.
+_STORED_AS_BASE_RE = re.compile(r"[^A-Za-z0-9._-]")
+
+
+def _summarize_message(body: bytes, msg_id: str) -> dict:
+    """Parse the DATA body and extract forensic metadata.
+
+    Returns a dict with:
+        subject, from_hdr, to_hdr, date_hdr, message_id_hdr, content_type,
+        attachments: list of {filename, content_type, size, sha256}.
+    Headers are RFC 2047 decoded. Attachment hashing uses the *decoded*
+    payload so operators can match against VT / MalwareBazaar directly.
+    """
+    try:
+        msg: Message = message_from_bytes(body)
+    except Exception:
+        return {
+            "subject": "", "from_hdr": "", "to_hdr": "", "date_hdr": "",
+            "message_id_hdr": "", "content_type": "", "attachments": [],
+        }
+
+    attachments: list[dict] = []
+    for part in msg.walk():
+        if part.is_multipart():
+            continue
+        disposition = (part.get("Content-Disposition") or "").lower()
+        filename = part.get_filename()
+        # Treat any part with an explicit filename as an attachment, even
+        # when Content-Disposition is missing — spam kits frequently omit it.
+        if not filename and "attachment" not in disposition:
+            continue
+        try:
+            payload = part.get_payload(decode=True) or b""
+        except Exception:
+            payload = b""
+        attachments.append({
+            "filename": _decode_header(filename) or "",
+            "content_type": part.get_content_type(),
+            "size": len(payload),
+            "sha256": hashlib.sha256(payload).hexdigest() if payload else "",
+        })
+
+    return {
+        "subject": _decode_header(msg.get("Subject")),
+        "from_hdr": _decode_header(msg.get("From")),
+        "to_hdr": _decode_header(msg.get("To")),
+        "date_hdr": _decode_header(msg.get("Date")),
+        "message_id_hdr": _decode_header(msg.get("Message-ID")),
+        "content_type": msg.get_content_type(),
+        "attachments": attachments,
+    }
+
+
+def _persist_message(body: bytes, msg_id: str) -> str | None:
+    """Write the raw DATA body to the quarantine dir as a .eml file.
+
+    Returns the stored_as basename on success, None if capture is disabled
+    or the write failed. The SMTP reply is always 250 regardless — a real
+    relay is opaque about its storage path.
+    """
+    if not _QUARANTINE_DIR:
+        return None
+    sha = hashlib.sha256(body).hexdigest()
+    ts = datetime.now(timezone.utc).strftime("%Y-%m-%dT%H:%M:%SZ")
+    safe_id = _STORED_AS_BASE_RE.sub("_", msg_id)[:32] or "msg"
+    stored_as = f"{ts}_{sha[:12]}_{safe_id}.eml"
+    try:
+        with open(os.path.join(_QUARANTINE_DIR, stored_as), "wb") as fh:
+            fh.write(body)
+        return stored_as
+    except OSError:
+        return None
+
+
+def _decode_auth_plain(blob: str) -> tuple[str, str]:
+    """Decode SASL PLAIN: base64(authzid\0authcid\0passwd) → (user, pass)."""
+    try:
+        decoded = base64.b64decode(blob + "==").decode(errors="replace")
+        parts = decoded.split("\x00")
+        if len(parts) >= 3:
+            return parts[1], parts[2]
+        if len(parts) == 2:
+            return parts[0], parts[1]
+    except Exception:
+        pass
+    return blob, ""
+
+
+class SMTPProtocol(asyncio.Protocol):
+    def __init__(self):
+        self._transport = None
+        self._peer      = ("?", 0)
+        self._buf       = b""
+        # per-transaction state
+        self._mail_from  = ""
+        self._rcpt_to: list[str] = []
+        # DATA accumulation
+        self._in_data   = False
+        self._data_buf: list[str] = []
+        # Running byte count for the DATA body; once this exceeds
+        # _MAX_BODY_BYTES we stop appending to _data_buf but keep
+        # consuming lines so the session still terminates cleanly.
+        self._data_bytes = 0
+        self._data_truncated = False
+        # AUTH multi-step state (LOGIN mechanism sends user/pass in separate lines)
+        self._auth_state  = ""   # "" | "await_user" | "await_pass"
+        self._auth_user   = ""
+
+    # ── asyncio.Protocol ──────────────────────────────────────────────────────
+
+    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])
+        transport.write(f"{_SMTP_BANNER}\r\n".encode())
+
+    def data_received(self, data):
+        self._buf += data
+        while b"\n" in self._buf:
+            line, self._buf = self._buf.split(b"\n", 1)
+            # Strip trailing \r so both CRLF and bare LF work
+            self._handle_line(line.rstrip(b"\r").decode(errors="replace"))
+
+    def connection_lost(self, exc):
+        _log("disconnect", src=self._peer[0] if self._peer else "?")
+
+    # ── Command dispatch ──────────────────────────────────────────────────────
+
+    def _handle_line(self, line: str) -> None:
+        # ── DATA body accumulation ────────────────────────────────────────────
+        if self._in_data:
+            if line == ".":
+                body_str = "\r\n".join(self._data_buf)
+                body = body_str.encode("utf-8", errors="replace")
+                msg_id = _rand_msg_id()
+                _log("message_accepted",
+                     src=self._peer[0],
+                     mail_from=self._mail_from,
+                     rcpt_to=",".join(self._rcpt_to),
+                     body_bytes=len(body),
+                     truncated=int(self._data_truncated),
+                     msg_id=msg_id)
+                # Persist the full .eml into the quarantine bind mount
+                # (if configured) and emit a richer event so the collector
+                # can index attachments + headers. This is the hook the
+                # dashboard's "sent mail" viewer reads.
+                stored_as = _persist_message(body, msg_id)
+                if stored_as is not None:
+                    summary = _summarize_message(body, msg_id)
+                    _log(
+                        "message_stored",
+                        src=self._peer[0],
+                        msg_id=msg_id,
+                        stored_as=stored_as,
+                        sha256=hashlib.sha256(body).hexdigest(),
+                        size=len(body),
+                        truncated=int(self._data_truncated),
+                        mail_from=self._mail_from,
+                        rcpt_to=",".join(self._rcpt_to),
+                        subject=summary["subject"][:512],
+                        from_hdr=summary["from_hdr"][:256],
+                        to_hdr=summary["to_hdr"][:512],
+                        date_hdr=summary["date_hdr"][:64],
+                        message_id_hdr=summary["message_id_hdr"][:256],
+                        content_type=summary["content_type"],
+                        attachment_count=len(summary["attachments"]),
+                        # Full manifest (filename/sha256/size/content_type)
+                        # rides as a compact JSON blob — the SD-value escape
+                        # in syslog_bridge handles the quotes and brackets.
+                        attachments_json=json.dumps(summary["attachments"], separators=(",", ":")),
+                    )
+                # Real MTAs take tens of ms to queue; instantaneous replies
+                # on DATA are a tell.
+                _seed.jitter_sync(30, 180)
+                self._transport.write(f"250 2.0.0 Ok: queued as {msg_id}\r\n".encode())
+                self._in_data         = False
+                self._data_buf        = []
+                self._data_bytes      = 0
+                self._data_truncated  = False
+                self._mail_from       = ""
+                self._rcpt_to         = []
+            else:
+                # RFC 5321 dot-stuffing: strip leading dot
+                decoded = line[1:] if line.startswith(".") else line
+                # +2 accounts for the CRLF that rejoins this line to the body.
+                new_total = self._data_bytes + len(decoded.encode("utf-8", errors="replace")) + 2
+                if new_total <= _MAX_BODY_BYTES:
+                    self._data_buf.append(decoded)
+                    self._data_bytes = new_total
+                else:
+                    # Stop appending but keep consuming so the client's
+                    # final CRLF.CRLF still terminates the state machine.
+                    self._data_truncated = True
+            return
+
+        # ── AUTH multi-step (LOGIN / PLAIN continuation) ─────────────────────
+        if self._auth_state == "await_plain":
+            user, password = _decode_auth_plain(line)
+            self._finish_auth(user, password)
+            self._auth_state = ""
+            return
+        if self._auth_state == "await_user":
+            self._auth_user  = base64.b64decode(line + "==").decode(errors="replace")
+            self._auth_state = "await_pass"
+            self._transport.write(b"334 UGFzc3dvcmQ6\r\n")  # "Password:"
+            return
+        if self._auth_state == "await_pass":
+            password = base64.b64decode(line + "==").decode(errors="replace")
+            self._finish_auth(self._auth_user, password)
+            self._auth_state = ""
+            self._auth_user  = ""
+            return
+
+        # ── Normal command dispatch ───────────────────────────────────────────
+        parts = line.split(None, 1)
+        cmd   = parts[0].upper() if parts else ""
+        args  = parts[1] if len(parts) > 1 else ""
+
+        if cmd in ("EHLO", "HELO"):
+            if not args:
+                self._transport.write(
+                    f"501 5.5.4 Syntax: {cmd} hostname\r\n".encode()
+                )
+                return
+            _log("ehlo", src=self._peer[0], domain=args)
+            self._transport.write(
+                f"250-{_SMTP_MTA}\r\n"
+                f"250-PIPELINING\r\n"
+                f"250-SIZE 10240000\r\n"
+                f"250-VRFY\r\n"
+                f"250-ETRN\r\n"
+                f"250-AUTH PLAIN LOGIN\r\n"
+                f"250-ENHANCEDSTATUSCODES\r\n"
+                f"250-8BITMIME\r\n"
+                f"250 DSN\r\n".encode()
+            )
+
+        elif cmd == "AUTH":
+            self._handle_auth(args)
+
+        elif cmd == "MAIL":
+            addr = args.split(":", 1)[1].strip() if ":" in args else args
+            self._mail_from = addr
+            # Strip <…> wrappers around the address; everything after the
+            # last @ is the domain. Empty when the attacker sent <> or a
+            # malformed envelope; keeping value= for back-compat with any
+            # log query that still reads it.
+            _bare = addr.strip("<>").strip()
+            _domain = _bare.rsplit("@", 1)[-1] if "@" in _bare else ""
+            _log("mail_from", src=self._peer[0], value=addr,
+                 mail_from=_bare, domain=_domain)
+            self._transport.write(b"250 2.1.0 Ok\r\n")
+
+        elif cmd == "RCPT":
+            addr = args.split(":", 1)[1].strip() if ":" in args else args
+            if OPEN_RELAY:
+                match = _ADDR_RE.match(addr)
+                if not match:
+                    _log("rcpt_rejected_syntax", src=self._peer[0], value=addr,
+                         severity=SEVERITY_WARNING)
+                    self._transport.write(
+                        b"501 5.1.3 Bad recipient address syntax\r\n"
+                    )
+                elif match.group(2).rsplit(".", 1)[-1].lower() in _BLOCKED_TLDS:
+                    _log("rcpt_rejected_tld", src=self._peer[0], value=addr,
+                         severity=SEVERITY_WARNING)
+                    self._transport.write(
+                        b"550 5.1.2 <" + addr.encode()
+                        + b">: Recipient address rejected: Domain not found\r\n"
+                    )
+                elif _rand.random() < _RCPT_DROP_RATE:
+                    _log("rcpt_greylisted", src=self._peer[0], value=addr)
+                    self._transport.write(
+                        b"451 4.7.1 <" + addr.encode()
+                        + b">: Recipient address rejected: Greylisted, try again later\r\n"
+                    )
+                else:
+                    self._rcpt_to.append(addr)
+                    _log("rcpt_to", src=self._peer[0], value=addr)
+                    self._transport.write(b"250 2.1.5 Ok\r\n")
+            else:
+                _log("rcpt_denied", src=self._peer[0], value=addr,
+                     severity=SEVERITY_WARNING)
+                self._transport.write(
+                    b"554 5.7.1 <" + addr.encode() + b">: Relay access denied\r\n"
+                )
+
+        elif cmd == "DATA":
+            if not self._rcpt_to:
+                self._transport.write(b"503 5.5.1 Error: need RCPT command\r\n")
+            else:
+                self._in_data = True
+                self._transport.write(b"354 End data with <CR><LF>.<CR><LF>\r\n")
+
+        elif cmd == "RSET":
+            self._mail_from  = ""
+            self._rcpt_to    = []
+            self._in_data    = False
+            self._data_buf   = []
+            self._data_bytes = 0
+            self._data_truncated = False
+            self._auth_state = ""
+            self._auth_user  = ""
+            self._transport.write(b"250 2.0.0 Ok\r\n")
+
+        elif cmd == "VRFY":
+            _log("vrfy", src=self._peer[0], value=args)
+            self._transport.write(b"252 2.0.0 Cannot VRFY user\r\n")
+
+        elif cmd == "NOOP":
+            self._transport.write(b"250 2.0.0 Ok\r\n")
+
+        elif cmd == "STARTTLS":
+            self._transport.write(b"454 4.7.0 TLS not available due to local problem\r\n")
+
+        elif cmd == "QUIT":
+            self._transport.write(b"221 2.0.0 Bye\r\n")
+            self._transport.close()
+
+        else:
+            _log("unknown_command", src=self._peer[0], command=line[:128])
+            self._transport.write(b"502 5.5.2 Error: command not recognized\r\n")
+
+    # ── AUTH helpers ──────────────────────────────────────────────────────────
+
+    def _handle_auth(self, args: str) -> None:
+        parts    = args.split(None, 1)
+        mech     = parts[0].upper() if parts else ""
+        initial  = parts[1] if len(parts) > 1 else ""
+
+        if mech == "PLAIN":
+            if initial:
+                user, password = _decode_auth_plain(initial)
+                self._finish_auth(user, password)
+            else:
+                # Client will send credentials on next line
+                self._auth_state = "await_plain"
+                self._transport.write(b"334 \r\n")
+        elif mech == "LOGIN":
+            if initial:
+                self._auth_user  = base64.b64decode(initial + "==").decode(errors="replace")
+                self._auth_state = "await_pass"
+                self._transport.write(b"334 UGFzc3dvcmQ6\r\n")  # "Password:"
+            else:
+                self._auth_state = "await_user"
+                self._transport.write(b"334 VXNlcm5hbWU6\r\n")  # "Username:"
+        else:
+            self._transport.write(b"504 5.5.4 Unrecognized authentication mechanism\r\n")
+
+    def _finish_auth(self, username: str, password: str) -> None:
+        _log("auth_attempt", src=self._peer[0],
+             username=username, principal=username,
+             severity=SEVERITY_WARNING, **encode_secret(password))
+        if not OPEN_RELAY:
+            self._transport.write(b"535 5.7.8 Error: authentication failed\r\n")
+            return
+        # Open-relay mode: still be selective so the decoy doesn't look like a
+        # tarpit that accepts literally anything. If no whitelist is set,
+        # accept; otherwise gate on username presence.
+        accepted = not _AUTH_WHITELIST or username in _AUTH_WHITELIST
+        if accepted:
+            self._transport.write(b"235 2.7.0 Authentication successful\r\n")
+        else:
+            self._transport.write(b"535 5.7.8 Error: authentication failed\r\n")
+
+
+async def main():
+    mode = "open-relay" if OPEN_RELAY else "credential-harvester"
+    _log("startup", msg=f"SMTP server starting as {NODE_NAME} ({mode})")
+    loop = asyncio.get_running_loop()
+    server = await loop.create_server(SMTPProtocol, "0.0.0.0", PORT)  # nosec B104
+    async with server:
+        await server.serve_forever()
+
+
+if __name__ == "__main__":
+    asyncio.run(main())

decnet/templates/smtp/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