Easy to setup and use network device discovery and alert system
Licensed under AGPL v3. See LICENSE.
OOTT runs behind the scenes and monitors your local network, notifying you when something changes. Its most relevant features are:
- Scans the network regularly using ARP probes, with additional mDNS, SSDP, DHCP and (optionally) SNMP discovery
- Notifies you when a new device is found
- Notifies you when a device changes its IP address or network interface vendor (based on its MAC address)
- Notifies you when a device comes back online after a configurable period of being offline
You configure and browse the data it collects through a companion app available on the web, desktop, iOS and Android.
 |
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| Web UI | Mobile app |
This is the quickest way to get OOTT running. OOTT is published on Docker Hub as a pre-built image, rzuasti/oott, and the steps below get you to a running service with the smallest possible configuration.
You need somewhere on the host to store the configuration file and the database (OOTT uses SQLite, so the database folder should be on local — not remote — storage):
mkdir -p /docker/oott/config
mkdir -p /docker/oott/dbThe user that runs Docker needs read access to the config folder and read/write access to the db folder. You can use any paths you like as long as you keep the volume mappings below in sync.
Create a minimal oott.toml at /docker/oott/config/oott.toml:
[database]
path = "/db/oott.db" # Must be "/db/oott.db" for the Docker image (the mounted volume)
[web_server]
api_key = "CHANGE_ME" # API key the app uses to talk to the backend — change this!
[notifications]
method = "pushover" # Use "none" to only log notifications instead of sending them
# Only needed when method = "pushover"; omit this section for any other method.
[notifications.pushover]
token = "" # Your Pushover application token
user_key = "" # Your Pushover user keyThis is enough to start the service; every other option falls back to a sensible default. See Full list of configuration options for everything you can tune, and the full sample config for a commented, all-options file.
Create a docker-compose.yml at /docker/oott/docker-compose.yml:
name: oott
services:
oott:
image: rzuasti/oott:latest
volumes:
- /docker/oott/config:/config
- /docker/oott/db:/db
network_mode: hostHost networking is required so OOTT can see the multicast and broadcast traffic its scanners rely on (see Privileges and network ports).
Start the service from where you placed the compose file:
docker compose up -dThat's it. Check that everything is running with docker ps, and follow the logs with docker logs CONTAINER_ID -f.
The official OOTT apps for iOS and Android are available as a one-time paid purchase on the App Store and Google Play. Buying them is the easiest way to get OOTT and directly supports its ongoing development. 💚
OOTT is and will remain fully open source. If you'd prefer not to pay, you're free to build and run the apps yourself from this repository at no cost, under the terms of the AGPL-3.0. (If you redistribute your own build, see the Trademark note — it must use its own name and branding, not "OOTT".)
The OOTT app (web, desktop, iOS and Android) talks to the backend exclusively over its REST API on port 3000. Open the app's settings and point it at your backend's address on the local network over HTTP, for example http://192.168.1.50:3000, using the API key you set in web_server.api_key.
This is the simplest setup and needs no extra infrastructure, but it only works while your phone is on the same local network as the backend.
Important
On iOS, the direct HTTP connection only works when you use the backend's private-range IP address (192.168.x.x, 10.x.x.x, 172.16–31.x.x) or a *.local (mDNS/Bonjour) name. A custom internal domain (e.g. oott.mylan.com) served over plain HTTP is blocked by iOS App Transport Security, even when it resolves to a private IP. Use the IP address directly, or set up HTTPS.
Note
The first time the iOS app reaches your backend on the local network, iOS shows a one-time "find devices on your local network" prompt. This is expected — tap Allow to continue.
To use a domain name, or to reach the backend from outside the local network, set up TLS as described in Using HTTPS and domain names with the mobile apps.
OOTT comes with a pre-built NixOS flake that you can integrate into your configuration. If you are not using flakes you can use the flake code as a baseline and write your own derivation.
To integrate the OOTT flake into your config you generally do three things: add OOTT to your inputs, add its module and overlay, then enable and configure the service.
1. Add OOTT to your inputs — in your flake.nix inputs section:
inputs = {
...
oott = {
url = "github:rzuasti/oott";
inputs.nixpkgs.follows = "nixpkgs";
};
...
};2. Add the OOTT module and overlay — in your flake.nix modules section:
...
modules = [
...
oott.nixosModules.oott
({pkgs, ...}: {
nixpkgs.overlays = [
oott.overlays.default
];
})
...
];
...3. Enable and configure OOTT — in your configuration.nix (or an imported file). Set all options through the service definition; the keys mirror the config file options listed below:
{
pkgs,
...
}
: {
environment.systemPackages = with pkgs; [
oott
];
services.oott = {
enable = true;
database.path = "/var/lib/oott.db";
web_server.api_key = "CHANGE_ME"; # API key the app uses to talk to the backend — change this!
# networking.interface = "eth0"; # Optional: auto-detected if not set
log.level = "warn";
arp_scanner.wait_between_scans = "30m";
arp_scanner.sender_timeout = "1m";
arp_scanner.scan_duration = "10m";
notifications.method = "pushover";
notifications.notify_when_not_seen_for = "1w";
notifications.pushover.token = "YOUR API TOKEN GOES HERE";
notifications.pushover.user_key = "YOUR USER TOKEN GOES HERE";
retention.window = "365d";
device_events.deduplication_window = "1m";
};
}The system configuration lives in a single config file, which you can write in TOML, JSON or YAML. With Docker, TOML is recommended — the full sample config lists every supported option with comments. With the Nix flake, set the same options through the service definition (see above).
Options marked Required have no built-in default and must be set in your config file. Everything else falls back to the default shown if you omit it.
| Option | Default value | Description |
|---|---|---|
database.path |
Required | Location of the system database. Must be /db/oott.db when using the Docker image. |
networking.interface |
auto-detected | Network interface to use for scans. Optional — if not set, the first non-loopback connected interface is used automatically. |
log.level |
warn |
Log level to use (off, error, warn, info, debug, trace) |
web_server.ip_address |
0.0.0.0 |
Address the API and web UI bind to. Use 0.0.0.0 to bind all interfaces. |
web_server.port |
3000 |
Port the API and web UI listen on. |
web_server.api_key |
Required | API key the app must present to use the backend. |
arp_scanner.enabled |
true |
Whether to run the ARP scanner. The whole [arp_scanner] section is optional; omit it to use the defaults below. Set to false to turn it off. |
arp_scanner.wait_between_scans |
30m |
Time to wait between each network scan (you can express it in seconds, minutes, hours, etc. as a suffix - for example: 30s, 10m, 1h) |
arp_scanner.sender_timeout |
1m |
If the ARP sender process takes longer than this it will be stopped (for a class C network - 254 IPs - it should take less than a minute) |
arp_scanner.scan_duration |
10m |
How long to wait for response packets on each scan (5m to 10m is a good timeframe for a class B or C network) |
mdns_scanner.enabled |
true |
Whether to run the mDNS/Bonjour scanner. Set to false to turn it off. |
mdns_scanner.probe_timeout |
2s |
When an mDNS-discovered IP is not in the OS ARP cache, how long to wait for a targeted ARP probe reply to resolve its MAC address |
ssdp_scanner.enabled |
true |
Whether to run the SSDP/UPnP scanner. Set to false to turn it off. |
ssdp_scanner.probe_timeout |
2s |
When an SSDP/UPnP-discovered IP is not in the OS ARP cache, how long to wait for a targeted ARP probe reply to resolve its MAC address |
dhcp_scanner.enabled |
true |
Whether to run the DHCP scanner. Set to false to turn it off. |
snmp_scanner.enabled |
false |
Whether to run the SNMP scanner. The whole [snmp_scanner] section is optional and the scanner stays off unless you add it; once the section is present it defaults to true. |
snmp_scanner.target |
Required | SNMP agent to poll, as host:port (e.g. your gateway: 192.168.1.1:161). The scanner reads the agent's ARP table over SNMPv2c — no local probing. Required when the [snmp_scanner] section is present. |
snmp_scanner.community |
Required | SNMPv2c read-only community string. Use a read-only community and never commit a real secret. Required when the [snmp_scanner] section is present. |
snmp_scanner.wait_between_scans |
10m |
Time to wait between polls. Keep it well under the agent's ARP cache timeout so active devices aren't missed. |
snmp_scanner.timeout |
5s |
Per-poll SNMP request timeout. |
notifications.method |
Required | How notifications are delivered. One of: pushover (send via Pushover), push (native push to the OOTT mobile apps through the project-operated relay), or none (don't send, just log). |
notifications.notify_when_not_seen_for |
1w |
Send a notification if a device comes back online after not being seen for this timeframe (you can use hours, weeks, etc.) |
notifications.pushover.token |
Required when method is pushover |
Your pushover token goes here, just copy&paste from their website after creating the app. The whole [notifications.pushover] section may be omitted when method is anything other than pushover |
notifications.pushover.user_key |
Required when method is pushover |
User key goes here, this is the account wide code for pushover. The whole [notifications.pushover] section may be omitted when method is anything other than pushover |
notifications.push.relay_url |
project relay (built-in) | Endpoint of the push relay used when method is push. The whole [notifications.push] section is optional: with method = "push" and no section, the built-in project-operated relay is used — you need set nothing. Override this only if you run your own relay. |
retention.window |
365d |
How long to retain device events and notifications. Records older than this are purged daily. Accepts duration strings — d days, w weeks, h hours, m minutes (e.g. 90d, 2w, 1y). |
device_events.deduplication_window |
1m |
Suppress duplicate device events: if the same scanner sees the same device (same MAC and IPv4) again within this window, only one event is recorded. Accepts duration strings (e.g. 30s, 1m, 5m). |
To reach the backend through a domain name, or from outside the local network, put it behind a reverse proxy (nginx, Caddy, Traefik, …) that terminates TLS with a valid certificate from a trusted CA (for example Let's Encrypt), then point the app at the HTTPS URL (e.g. https://oott.example.com). This works on every platform — including iOS — with no further configuration.
Connect using the domain name the certificate is issued for, not an IP address. Self-signed certificates are not supported unless they are manually trusted on the device.
OOTT does not provide built-in user accounts or permission management. Access to the backend is gated only by the web_server.api_key you configure.
If you want proper user authentication (login pages, multiple users, single sign-on, etc.), add an authentication layer in front of OOTT — for example TinyAuth, Authentik or a similar reverse-proxy authentication solution.
Important
Do not apply that authentication layer to the /api URIs. The mobile apps and web front-end talk to the backend over /api using the API key.
OOTT stores a timestamped event for every device sighting, so the database grows with the number of devices on your network and how long you keep history.
Assumptions for the estimates below:
- The four scanners that are on by default are running (ARP, mDNS, SSDP and DHCP). The SNMP scanner is disabled by default and not included.
- Default configuration, with
retention.window = 365d(one year of history). - Figures are typical averages, not worst case — real usage is often lower.
| Network size | Active devices | Estimated storage / year |
|---|---|---|
| Home | 20–50 | ~150–350 MB |
| Homelab | 50–100 | ~350–700 MB |
| Small office | 100–200 | ~0.7–1.4 GB |
| Medium office | 200–500 | ~1.4–3.5 GB |
You have three main levers, in rough order of impact:
1. Retention window (retention.window) — how far back history is kept. This scales storage linearly: halving the window halves the storage.
2. Enabled scanners — each scanner you turn off removes its share. The three passive scanners (mDNS/SSDP/DHCP) generate most of the events; disabling them leaves just the ARP baseline (≈1.9 MB/device/year).
3. ARP scan interval (arp_scanner.wait_between_scans) — a longer interval means fewer ARP events. This only affects the ARP share, so its overall impact is modest while the passive scanners run.
The deduplication window (
device_events.deduplication_window, default1m) caps how often a single device can be recorded — at most one event per scanner per minute. It's a safety limit for chatty devices, not a routine tuning knob.
OOTT binds to the following ports on the host where it runs:
| Port | Protocol | Configurable | Used by |
|---|---|---|---|
3000 |
TCP | Yes (web_server.port) |
REST API and web UI |
5353 |
UDP (multicast) | No — fixed | mDNS/Bonjour scanner |
1900 |
UDP (multicast) | No — fixed | SSDP/UPnP scanner |
67 |
UDP (broadcast) | No — fixed | DHCP scanner |
The mDNS (UDP 5353), SSDP (UDP 1900) and DHCP (UDP 67) ports are fixed by their respective protocols and cannot be changed. They must be available on the server where OOTT runs.
OOTT binds these sockets with address/port reuse, so it can run alongside other responders already listening on them (for example avahi on 5353, minidlna on 1900, or a DHCP server/relay on 67). However, the ports must not be blocked by a host firewall, and the corresponding multicast/broadcast traffic must be allowed to reach the host — otherwise the scanners will not discover any devices.
Important
OOTT needs elevated privileges: the ARP scanner requires raw-socket access, and port 67 is a privileged port. The pre-built Docker image and NixOS module already run with what they need.
Under Docker, the scanners require host networking (or an equivalent setup that exposes the host's multicast and broadcast traffic to the container), as shown in the Docker installation above.
"OOTT", the OOTT name, and the OOTT logo are trademarks of Ricardo Zuasti and are not licensed under the AGPL-3.0. The AGPL-3.0 grants you full rights to the source code — to use, modify, build, run, and redistribute it — but it does not grant any right to use the OOTT name, branding, or logo.
If you build or distribute your own version of this software, you must do so under a different name and branding and must not present it as the official OOTT app. This keeps users from confusing third-party builds with the official, supported release.