Add per-service customization, stealth hardening, and BYOS support

- HTTP: configurable server_header, response_code, fake_app presets
  (apache/nginx/wordpress/phpmyadmin/iis), extra_headers, custom_body,
  static files directory mount
- SSH/Cowrie: configurable kernel_version, hardware_platform, ssh_banner,
  and users/passwords via COWRIE_USERDB_ENTRIES; switched to build mode
  so cowrie.cfg.j2 persona fields and userdb.txt generation work
- SMTP: configurable banner and MTA hostname
- MySQL: configurable version string in protocol greeting
- Redis: configurable redis_version and os string in INFO response
- BYOS: [custom-*] INI sections define bring-your-own Docker services
- Stealth: rename all *_honeypot.py → server.py; replace HONEYPOT_NAME
  env var with NODE_NAME across all 22+ service templates and plugins;
  strip "honeypot" from all in-container file content
- Config: DeckyConfig.service_config dict; INI [decky-N.svc] subsections;
  composer passes service_cfg to compose_fragment
- 350 tests passing (100%)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

templates/mqtt/server.py

@@ -0,0 +1,148 @@
+#!/usr/bin/env python3
+"""
+MQTT server (port 1883).
+Parses MQTT CONNECT packets, extracts client_id, username, and password,
+then returns CONNACK with return code 5 (not authorized). Logs all
+interactions as JSON.
+"""
+
+import asyncio
+import json
+import os
+import socket
+import struct
+from datetime import datetime, timezone
+
+NODE_NAME = os.environ.get("NODE_NAME", "mqtt-broker")
+LOG_TARGET = os.environ.get("LOG_TARGET", "")
+
+# CONNACK: packet type 0x20, remaining length 2, session_present=0, return_code=5
+_CONNACK_NOT_AUTH = b"\x20\x02\x00\x05"
+
+
+def _forward(event: dict) -> None:
+    if not LOG_TARGET:
+        return
+    try:
+        host, port = LOG_TARGET.rsplit(":", 1)
+        with socket.create_connection((host, int(port)), timeout=3) as s:
+            s.sendall((json.dumps(event) + "\n").encode())
+    except Exception:
+        pass
+
+
+def _log(event_type: str, **kwargs) -> None:
+    event = {
+        "ts": datetime.now(timezone.utc).isoformat(),
+        "service": "mqtt",
+        "host": NODE_NAME,
+        "event": event_type,
+        **kwargs,
+    }
+    print(json.dumps(event), flush=True)
+    _forward(event)
+
+
+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):
+    """Extract client_id, username, password from MQTT CONNECT payload."""
+    pos = 0
+    # Protocol name
+    proto_name, pos = _read_utf8(payload, pos)
+    # Protocol level (1 byte)
+    if pos >= len(payload):
+        return {}, pos
+    _proto_level = payload[pos]; pos += 1
+    # Connect flags (1 byte)
+    if pos >= len(payload):
+        return {}, pos
+    flags = payload[pos]; pos += 1
+    # Keep alive (2 bytes)
+    pos += 2
+    # Client ID
+    client_id, pos = _read_utf8(payload, pos)
+    result = {"client_id": client_id, "proto": proto_name}
+    # Will flag
+    if flags & 0x04:
+        _, pos = _read_utf8(payload, pos)  # will topic
+        _, pos = _read_utf8(payload, pos)  # will message
+    # Username flag
+    if flags & 0x80:
+        username, pos = _read_utf8(payload, pos)
+        result["username"] = username
+    # Password flag
+    if flags & 0x40:
+        password, pos = _read_utf8(payload, pos)
+        result["password"] = password
+    return result
+
+
+class MQTTProtocol(asyncio.Protocol):
+    def __init__(self):
+        self._transport = None
+        self._peer = None
+        self._buf = b""
+
+    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
+        self._process()
+
+    def _process(self):
+        while len(self._buf) >= 2:
+            pkt_type = (self._buf[0] >> 4) & 0x0f
+            # Decode remaining length (variable-length encoding)
+            pos = 1
+            remaining = 0
+            multiplier = 1
+            while pos < len(self._buf):
+                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)
+                _log("auth", src=self._peer[0], **info)
+                self._transport.write(_CONNACK_NOT_AUTH)
+                self._transport.close()
+            elif pkt_type == 12:  # PINGREQ
+                self._transport.write(b"\xd0\x00")  # PINGRESP
+            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", 1883)
+    async with server:
+        await server.serve_forever()
+
+
+if __name__ == "__main__":
+    asyncio.run(main())