esp32-cluster/README.md

ESP32 WiFi Recon Cluster

What this is

A distributed WiFi reconnaissance system using ESP32-S3 nodes and an Orange Pi as coordinator. The goal is passive RF awareness — mapping what is happening in the surrounding WiFi environment without transmitting or interacting with any networks.

Each ESP32 node scans the WiFi environment, builds structured events (not raw data), and ships them over UDP to a coordinator. The coordinator stores events to SQLite. A separate web dashboard reads the database and displays everything in real time via SSE.

The system is designed around a clear separation of concerns: nodes are dumb sensors, the Orange Pi does all storage and analysis, the browser does all rendering. No logic lives on the nodes beyond capturing and formatting events.

Practical use cases this has already demonstrated:

• Mapping every network and client device in a city-center apartment building
• Detecting sustained deauth flood attacks targeting specific devices (confirmed live)
• Reconstructing device travel history from probe request SSID lists
• Identifying device types by OUI (phones, IoT devices, laptops, cars, smart home hardware)
• Correlating attack victims across multiple impersonated APs using deauth dst MAC

This is a learning/research project covering distributed systems, event-driven architecture, sensor fusion, and detection engineering concepts.

---

Hardware

• Nodes: ESP32-S3 N16R8 (4 active, scattered across apartment)
• Coordinator: Orange Pi at 192.168.1.133, runs 24/7 as systemd services
• Dev machine: This PC at 192.168.1.101 — coding and flashing only
• Flashing: Arduino CLI on this PC
• Pen testing: Parrot OS laptop at 192.168.1.124 (user: keny) — active investigation rig
• WiFi adapter: Alfa MT7612U (wlx00c0cab67193) — monitor mode + packet injection, plugged into Parrot laptop
• Pen testing tools: airgeddon at /home/keny/Documents/github_tools/airgeddon

Active nodes

node_id	MAC	Location
F68D6E30	44:1b:f6:8d:6e:30	room 1 (permanent)
A1D658D4	e0:72:a1:d6:58:d4	room 2 (permanent)
A1D700C4	e0:72:a1:d7:00:c4	room 3 (permanent)
A1D6F190	e0:72:a1:d6:f1:90	dev machine (desk, USB)

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Network

• ESP32 nodes connect to: WiFi SSID sandbox
• Coordinator IP: 192.168.1.133 (Orange Pi, production)
• UDP port: 5005
• Dashboard port: 8080
• Parrot laptop: 192.168.1.124 — SSH as keny, passwordless sudo configured

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Architecture

[ESP32 nodes] --UDP 5005--> [udp_ingest.py] --write--> [events.db (SQLite)]
                                                               |
[Browser] <--HTTP/SSE 8080-- [dashboard.py] ------read--------+

The two coordinator processes are intentionally separate. The ingestor has one job: receive UDP, write to DB. The dashboard has one job: read DB, serve UI. They communicate only through the database. Each is independently restartable without affecting the other.

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Development workflow

All coding is done on this PC. The Orange Pi only runs the deployed files — never edit directly on it.

[This PC] → edit code → rsync → [Orange Pi] → restart services

Sync to Orange Pi

bash /home/sandbox/Documents/projects/esp32_cluster/deploy.sh

This rsyncs coordinator/ to /opt/esp32_cluster/coordinator/ on the Orange Pi, excluding events.db (the Pi keeps its own database).

Restart services after deploy

ssh root@192.168.1.133 'systemctl restart udp_ingest dashboard'

View live logs on Orange Pi

# Ingestor (UDP events coming in)
ssh root@192.168.1.133 'journalctl -u udp_ingest -f'

# Dashboard
ssh root@192.168.1.133 'journalctl -u dashboard -f'

---

Project structure

esp32_cluster/
├── firmware/
│   └── node/
│       ├── node.ino              # ESP32 node firmware
│       └── config.h              # WiFi creds, coordinator IP, scan/probe config
├── coordinator/
│   ├── udp_ingest.py             # UDP listener — receives packets, validates, writes to SQLite
│   ├── dashboard.py              # FastAPI app — reads SQLite, serves UI + SSE stream
│   ├── templates/
│   │   └── dashboard.html        # Dashboard skeleton HTML
│   ├── static/
│   │   ├── dashboard.css         # All dashboard styles
│   │   └── dashboard.js          # All dashboard logic (vanilla JS)
│   ├── oui.txt                   # IEEE OUI database for vendor lookup (39k entries)
│   ├── udp_ingest.service        # systemd service file for ingestor
│   ├── dashboard.service         # systemd service file for dashboard
│   └── events.db                 # SQLite database — on Orange Pi only, not synced
├── deploy.sh                     # rsync script: this PC → Orange Pi
├── starting_plan.md              # Original architecture design doc
└── README.md                     # This file

---

Firmware

Each node:

• Connects to WiFi sandbox
• Scans for nearby APs every 15 seconds (active scan, includes hidden SSIDs)
• Hops across all 13 2.4 GHz channels (300ms dwell per channel) while sniffing
• Captures probe request frames passively (promiscuous mode) between scans
• Captures deauth and disassoc frames (0xC0 / 0xA0)
• Captures association and reassociation request frames (0x00 / 0x20) with SSID IE parsing
• Sends a heartbeat packet every 10 seconds (uptime, free heap, WiFi RSSI to router, queue drop counters)
• Sends all events as UDP JSON packets to the coordinator
• node_id is derived from bytes 2–5 of the ESP32's base MAC address
• Events are buffered in FreeRTOS queues and flushed once per scan cycle when back on the home channel
• If a deauth with reason code 2 is seen at RSSI ≥ -60 dBm, an alert flag triggers an immediate flush on the home channel without waiting for the next scan

Event formats

Beacon event (AP discovered):

{
  "node_id": "F68D6E30",
  "ts":      12345,
  "type":    "beacon",
  "conf":    "high",
  "imp":     "normal",
  "ssid":    "NetworkName",
  "bssid":   "AA:BB:CC:DD:EE:FF",
  "rssi":    -65,
  "ch":      6,
  "enc":     "WPA2"
}

Probe event (client device searching for a network):

{
  "node_id": "F68D6E30",
  "ts":      12345,
  "type":    "probe",
  "conf":    "high",
  "imp":     "normal",
  "src_mac": "AA:BB:CC:DD:EE:FF",
  "ssid":    "HomeNetwork",
  "rssi":    -55
}

Deauth / Disassoc event (management frame captured in promiscuous mode):

{
  "node_id": "F68D6E30",
  "ts":      12345,
  "type":    "deauth",
  "src":     "AA:BB:CC:DD:EE:FF",
  "dst":     "11:22:33:44:55:66",
  "bssid":   "AA:BB:CC:DD:EE:FF",
  "reason":  7,
  "rssi":    -61
}

• type is deauth (0xC0) or disassoc (0xA0)
• dst = FF:FF:FF:FF:FF:FF means broadcast deauth — a classic deauth flood signature
• reason is the 802.11 reason code (7 = class 3 frame received from non-associated station, common in attack tools)
• Captured passively in the same promiscuous callback as probe requests, flushed to coordinator after each scan cycle

Assoc / Reassoc event (client joining a network):

{
  "node_id": "F68D6E30",
  "ts":      12345,
  "type":    "assoc",
  "src":     "AA:BB:CC:DD:EE:FF",
  "bssid":   "11:22:33:44:55:66",
  "ssid":    "NetworkName",
  "rssi":    -55
}

• type is assoc (0x00) or reassoc (0x20)
• SSID is parsed from the first Information Element in the frame body (IE tag 0x00)
• Captures real client→AP join events, not just passive probe searches

Heartbeat event (node health, sent every 10 seconds):

{
  "node_id":      "F68D6E30",
  "ts":           12345,
  "type":         "heartbeat",
  "uptime_ms":    123456,
  "free_heap":    245000,
  "wifi_rssi":    -62,
  "probe_drops":  0,
  "deauth_drops": 0,
  "assoc_drops":  0
}

• probe_drops, deauth_drops, assoc_drops count events lost due to queue overflow since boot. Non-zero values indicate the node is seeing more traffic than the queue sizes can absorb.

• imp: high if RSSI >= -50, low if <= -80, else normal

• ssid in probe events is the network the device is searching for — empty means wildcard (any network)

• Probe dedup: same MAC+SSID suppressed for 30 seconds to avoid flooding

• wifi_rssi in heartbeat is the node's own signal to the sandbox AP (not a scanned network)

• A node is considered online if a heartbeat arrived within the last 30 seconds; falls back to beacon within 60 seconds if no heartbeat has been received yet

Flashing a node

Requirements: Arduino CLI v1.4.1, ESP32 core v3.3.7, FQBN esp32:esp32:esp32s3, user in dialout group.

# Compile
arduino-cli compile --fqbn esp32:esp32:esp32s3 /home/sandbox/Documents/projects/esp32_cluster/firmware/node/

# Flash — adjust port as needed (check with: ls /dev/ttyACM*)
arduino-cli upload --fqbn esp32:esp32:esp32s3 --port /dev/ttyACM0 \
  /home/sandbox/Documents/projects/esp32_cluster/firmware/node/

The same binary works on every node — node_id is auto-derived from the MAC, no per-node config needed.

Check group membership with groups. You should see dialout.

config.h reference

Constant	Default	Purpose
WIFI_SSID	sandbox	WiFi network to connect to
COORDINATOR_IP	192.168.1.133	Orange Pi address
COORDINATOR_PORT	5005	UDP port
SCAN_INTERVAL_MS	15000	How often to run a beacon scan (ms)
HEARTBEAT_INTERVAL_MS	10000	How often to send a heartbeat (ms)
PROBE_SNIFF	1	Enable/disable probe/deauth/assoc sniffing (1/0)
PROBE_DEDUP_SECS	30	Suppress duplicate probe MAC+SSID (secs)
DEDUP_CACHE_SIZE	64	Number of MAC+SSID pairs tracked for dedup
PROBE_QUEUE_SIZE	128	Max probe events buffered between flushes
DEAUTH_QUEUE_SIZE	128	Max deauth/disassoc events buffered
ASSOC_QUEUE_SIZE	32	Max assoc/reassoc events buffered
HOP_DWELL_MS	300	Ms to dwell on each channel while hopping (13ch × 300ms ≈ 4s)
RSSI_ALERT_THRESHOLD	-60	RSSI floor for immediate-flush deauth alert (dBm)

---

Orange Pi — running services

Services are managed by systemd and start automatically on boot.

# Status
ssh root@192.168.1.133 'systemctl status udp_ingest dashboard'

# Restart both
ssh root@192.168.1.133 'systemctl restart udp_ingest dashboard'

# Stop
ssh root@192.168.1.133 'systemctl stop udp_ingest dashboard'

Service files are in coordinator/ and deployed to /etc/systemd/system/ on the Orange Pi. The coordinator files live at /opt/esp32_cluster/coordinator/ on the Orange Pi.

---

Dashboard

Open http://192.168.1.133:8080 in your browser.

Views

• Feed — live beacon event stream across all nodes, capped at 100 rows, newest on top
• Networks — deduplicated AP table (by BSSID): times seen, best/avg RSSI, channel, encryption, node count. Sortable by any column. Each row has a ▶ button to open the RSSI history chart for that network.
• RSSI history chart — opens from any Networks row. Shows signal strength over time per node (1h / 2h / 6h / 24h selectable). Each node gets its own coloured line. Useful for spotting interference patterns, seeing how signal fluctuates by time of day, and comparing which node consistently hears a given AP better. Updates live as new scans arrive.
• Cross-node — side-by-side per-node RSSI for every AP. Shows which node is physically closer to each network. Filter to multi-node only to focus on confirmed cross-node observations.
• Clients — probe request data: unique MACs, vendor (OUI lookup), what SSIDs they're searching for, signal, which nodes saw them.
• Alerts — deauth/disassoc frame detection with four sections:
  • 1h Summary strip — total frames, deauth vs disassoc counts, unique BSSIDs and sources in the last hour
  • Most Impersonated Networks — APs whose BSSID is being spoofed as the deauth source, ranked by frame count
  • Most Targeted Devices — actual victim devices (by dst MAC), ranked by frames received across all impersonated APs
  • Detected Bursts — fires when ≥10 frames for the same BSSID within 5 minutes. Highlighted red when confirmed by 2+ nodes. Reason code 2 at volume is the primary attack indicator.
  • Raw Feed — last 100 deauth/disassoc events with full src/dst/BSSID/reason/RSSI detail.
• Search — cross-table lookup by any identifier. Supports MAC address, SSID, BSSID, and vendor name (e.g. "Raspberry", "Tuya", "Intel"). Returns all matching data across beacon, probe, and deauth tables in labelled sections. Vendor name search works by matching against the OUI database and finding all devices with those MAC prefixes.
• Presence — three sections driven entirely by probe data:
  • Present Now — real (non-randomized) MACs seen 2+ times in the last hour. Filters out the city-center noise of transient devices.
  • New Arrivals — devices and networks first seen in the last 24 hours, split into two side-by-side tables.
  • Regulars — devices and networks seen on 2 or more distinct calendar days. Takes at least two days of data to populate.
• Node detail — click a node in the sidebar for stats: total events, unique SSIDs/BSSIDs, RSSI range, first/last seen, uptime, free heap, AP signal, last 100 events.

Node detail

Click any node in the sidebar to open the detail view. Ten stat cards arranged in a 2×5 grid show: status, total events, unique SSIDs, unique BSSIDs, avg RSSI, first seen, last seen, uptime, free heap, and AP signal. Below the cards is a table of the last 100 events for that node.

Sidebar

Always visible: node list with online/offline status dot, last seen time, event count, and a compact heartbeat line (uptime · free heap · AP signal). Nodes are sorted alphabetically by node ID so the order stays fixed as more nodes are added. A node is considered online if a heartbeat was received within the last 30 seconds. Falls back to beacon timestamp (60s threshold) if no heartbeat has been received yet.

UI

Font: Roboto (Google Fonts). Chosen for readability at small sizes — the previous monospace font felt too thin at the smaller label sizes used throughout the dashboard.

Live updates

SSE stream pushes new beacon events as they arrive. The feed updates immediately. All other views (sidebar, networks, chart, cross-node, presence, alerts) refresh on a 2-second debounce so a single scan burst doesn't flood the server with requests.

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Observations and notes

Hidden networks

Networks with a blank SSID but valid BSSID, signal, and channel are hidden networks — APs configured not to broadcast their name. They are not hidden from passive scanners. The encryption showing as OPEN is a firmware parsing artifact; the network itself may be encrypted. The BSSID OUI still identifies the manufacturer.

Probe requests and MAC randomization

Modern phones and laptops (iOS since ~2020, Android since ~2021) randomize their MAC address for probe requests. A randomized MAC has bit 1 of the first byte set — the dashboard detects this and labels it "Randomized MAC" instead of doing a meaningless OUI lookup.

What probe data tells you:

• Directed probes (with SSID): the device has connected to that network in the past
• Wildcard probes (empty SSID): the device is searching for any available network
• Probe data maps client devices, not infrastructure — complementary to beacon scan data

Deauth frame noise vs real attacks

The raw deauth feed in the Alerts tab will fill up constantly — deauth and disassoc frames are a normal part of WiFi operation (devices disconnecting, APs doing band steering, power saving). This is expected and not cause for concern.

The Bursts section is the anomaly detector. A single unique source MAC generating 10+ deauth frames for the same BSSID within 5 minutes is not normal operation — it indicates a deauth flood, the standard precursor to a WPA2 handshake capture attack. The attacker forces connected clients to disconnect, captures the 4-way handshake when they reconnect, and then cracks it offline.

Multi-node confirmation (node_count > 1, highlighted red) significantly raises confidence — it means the source is physically close and strong, not a distant weak signal.

Node dropout — AP overwhelm on simultaneous reconnect

Observed 2026-04-06: three of four nodes dropped off the dashboard after being power cycled individually at different times. Symptoms included reason-15 deauth floods (4-way handshake timeout) from the affected nodes captured by the surviving node, and nodes getting stuck in a reconnect loop without ever successfully sending data to the coordinator.

Root cause: the sandbox AP was overwhelmed by multiple nodes power cycling at slightly different times and hammering it with simultaneous association requests. Each node hops channels every ~4 seconds, briefly dropping and reconnecting to sandbox on every cycle. When several nodes do this at the same time after a staggered power cycle, the AP's association table fills with stale entries and stops completing WPA2 handshakes for new clients.

Confirmed not a firmware issue: all four nodes ran for 21 hours continuously without a single drop when power cycled simultaneously (clean start, all connect at once). Heap stayed stable across all nodes throughout (234K–247K, no drift).

Mitigation: power cycle all nodes at the same time rather than individually, so they all connect fresh together rather than in a staggered loop. Long-term fix is a dedicated AP for the nodes only, so their reconnect churn is isolated from regular network traffic and the AP is never competing with other clients.

Our own networks

To avoid investigating our own infrastructure, these SSIDs and BSSIDs are ours:

SSID	Band	Purpose
sandbox	2.4GHz	Main network, nodes connect here
botnet	2.4GHz	IoT devices
pronet	5GHz	Main 5GHz network
mango	2.4GHz	Secondary network

sandbox BSSID 1C:3B:F3:9C:AC:30 appearing in deauth/impersonation data is expected — our own nodes briefly deauth from it during channel hopping and reconnect.

OUI lookup

The oui.txt file is the IEEE public OUI database (39,171 entries as of download). It maps the first 3 bytes of a real MAC to a manufacturer name. Used in the Clients tab. Refresh it occasionally by re-running deploy.sh after downloading a fresh copy from https://standards-oui.ieee.org/oui/oui.txt.

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Active investigations

Sustained deauth attack on Tuya device

A persistent automated deauth flood has been running since 2026-04-03, targeting 38:2C:E5:7E:77:1D (Tuya Smart Inc. device). Four spoofed source MACs fire simultaneously roughly every hour, all using reason code 2, impersonating real AP BSSIDs in the building. All 4 nodes confirm it. Consistent with an automated WPA2 handshake capture tool. No action taken yet — being passively monitored.

Attacker src MACs: 82:4E:66:47:09:C1, 42:8C:46:6E:12:9C, 62:D9:AA:E8:B4:09, 62:87:CB:38:2C:20

Living Room speaker (own device)

SSID: Living Room speaker.n078 · BSSID: FA:8F:CA:76:06:B2 · ch 6 · OPEN · RSSI -54 dBm (bathroom, same apartment).

Broadcasting an open unauthenticated hotspot. Next step: connect via Parrot laptop + Alfa adapter, nmap the provisioning interface, document what is exposed. Not yet started.

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Current status

• Arduino CLI installed, ESP32 core configured
• Node firmware: beacon scan + probe sniffing
• Four ESP32-S3 nodes flashed and running
• UDP ingestor (udp_ingest.py) — beacon + probe routing with field validation
• Web dashboard: Feed, Networks, Cross-node, Clients, Alerts, Search, Presence, Node detail
• OUI vendor lookup in Clients view (vendor grouping + randomized MAC detection)
• Dashboard split into HTML / CSS / JS (no monolithic file)
• Deployed to Orange Pi as systemd services (runs 24/7)
• All four nodes sending to Orange Pi, confirmed live
• Node heartbeat every 10s — uptime, free heap, AP signal, drives online/offline status
• RSSI history chart per network (canvas, per-node coloured lines, 1h/2h/6h/24h range)
• Presence tab — Present Now, New Arrivals, Regulars (fixed key mismatch bug)
• Deauth/disassoc frame detection — burst detection with multi-node confirmation, Alerts tab
• Alerts tab — most impersonated networks, most targeted devices, burst detection, raw feed
• Search tab — cross-table lookup by MAC, SSID, BSSID, or vendor name
• Node detail view — 2×5 stat cards with animated border, fixed alphabetical sidebar order
• Channel hopping — 13 channels at 300ms dwell, flush on homeChannel pass
• Assoc/reassoc frame capture — client join events with SSID IE parsing
• RSSI-triggered alert flush — immediate homeChannel flush on close-range deauth attack signature
• Queue drop counters — tracked per queue in firmware, reported in heartbeat, stored in DB
• SQLite indexes — received_at, node_id, bssid, src_mac, src, dst across all event tables
• Dashboard query caps — 300-row limits on Clients, Networks, Cross-node to keep UI responsive
• Sessions tab — deauth events grouped into sessions by source MAC + 2-min gap, sortable, expandable rows
• Dashboard performance overhaul — fixed tab switch latency and Networks tab failing to load (see below)
• DB pruning / retention policy — background task deletes events older than HOT_DAYS every 6 hours
• Alerts tab — dominant reason code added to Most Impersonated Networks and Most Targeted Devices tables
• Sessions tab — dominant reason code + description shown per session row and in expanded detail panel
• SSE reconnect bug fix — multiple stale EventSource instances were accumulating on reconnect, flooding /api/nodes on tab re-open; fixed with proper close-before-reconnect and in-flight guard
• Surface assoc events in dashboard (Search results or dedicated view)
• Scan interval control from dashboard
• Dedicated AP for nodes to isolate reconnect churn from regular network traffic

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Dashboard performance overhaul (2026-04-06)

Problem

Tab switches took up to a minute to load. The Networks tab failed to load entirely. The SSE live feed would stall during tab switches. The root cause was three compounding issues:

1. Blocking the async event loop. FastAPI routes are async def, but the SQLite calls (sqlite3 module) are fully synchronous. When called directly inside async def, they block uvicorn's entire event loop — meaning while one slow query runs, the server cannot serve any other request, including the SSE stream. This is why everything froze together.

2. Expensive endpoints had no caching. /api/alerts, /api/sessions, /api/presence, and /api/cross-node ran full database queries on every single request, with no result caching. The 2-second debounce on the frontend meant these were being called repeatedly.

build_sessions() was the worst: it pulled every deauth event from the last 30 days and grouped them into sessions in a Python loop — O(N) in Python on every call, with no cache. Under a sustained deauth flood (thousands of events/day), this was very slow.

build_alerts() ran several queries against the entire deauth_events table with no time cutoff — top targets, top targeted devices, reason breakdown, activity heatmap all scanned all-time data.

3. Unbounded database growth. No pruning meant every query got slower every day as the tables grew. The database had also developed B-tree corruption (double-referenced pages, out-of-order rowids), likely from WAL journal not checkpointing cleanly under sustained write load. The database was rebuilt clean.

Fixes applied

• asyncio.to_thread() — all build_* calls in every route are now dispatched to a thread pool executor. The event loop stays free to handle SSE and other requests while queries run in the background. The SSE generator's inline query() calls were also fixed the same way.

• Caching added — alerts (60s TTL), sessions (60s), presence (60s), cross-node (60s) now cache results in memory. The existing nodes/networks/clients caches were kept. Tab switches hit the cache on repeated loads rather than re-querying the DB.

• Time bounds on alerts queries — top targets, top targeted devices, reason breakdown, and activity heatmap are now scoped to the last 7 days instead of all-time. Still meaningful, no longer scanning the full table history.

• Composite indexes added — added (bssid, received_at) on beacon_events and deauth_events, and (src_mac, received_at) on probe_events. Queries that filter by time and aggregate by BSSID or MAC now use a single composite index instead of two separate ones.

• Background pruning task — at startup, a background coroutine runs every 6 hours and deletes rows older than HOT_DAYS (30 days) from all event tables, followed by a WAL checkpoint. The database will no longer grow indefinitely.

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Python dependencies

fastapi
uvicorn

pip install fastapi uvicorn