# Connect a sensor

> Add a Linux sensor over SSH, set up a freshly flashed unified sensor over USB, or pair an ESP32-C5 over Bluetooth LE.

Every scan, capture and test starts on the **Devices** screen. This guide covers the three ways a sensor reaches the app.

## What you need

| Sensor | How it connects | Platforms |
|---|---|---|
| NanoPi, Raspberry Pi, WLAN Pi or another Linux host | SSH over your network | iPhone, iPad, Android |
| Freshly flashed [unified image](/guides/unified-sensor-image/) | USB Ethernet link at `198.18.42.1`, then SSH | iPhone, iPad, Android |
| ESP32-C5 board | Bluetooth LE | iPhone, iPad, Android |

For other equipment, check the [compatibility reference](/sensors/compatibility/).

## How to add a Linux sensor over SSH

1. Power the sensor and connect it to the same Wi-Fi or LAN as your phone.
2. Open **Devices**. On iPhone, tap **Scan Network** to search again; on Android, tap **Refresh**.
3. Wait for the sensor to appear under **On This Network**.
4. Open the found sensor:
    - On iPhone, tap its row (or **+**). The **Add Discovered Device** form opens with the name, host and port filled in.
    - On Android, tap **Connect** on its row. A sensor that needs a login opens **Edit Device** so you can enter credentials.
5. If the sensor does not appear, add it by address. On iPhone, tap **Add Device** (the **+** button), or **Add Manually** on an empty list. On Android, tap **Add device** (**+**). Enter the name, host or IP address, and port (SSH is `22`).
6. Under **Authentication**, enter the **Username**. Choose **Password** or **Private Key**, then enter the password or key path.
7. Save:
    - On iPhone, leave **Connect after saving** on and tap **Save**.
    - On Android, tap **Save & test**. The app tests the login and shows **Connected.** when it works.
8. Tap the sensor's row to open its device detail. You should see it as connected, with its health and radios. To connect later, tap **Connect** on the row.

Enter the SSH account set up on that sensor. Older NanoPi and WLAN Pi images documented `wlanpi` / `wlanpi`. The app suggests the username `wlanpi` for those sensors, but you choose the password. Change any default password before you deploy. Do not assume these credentials work on other equipment.

The [unified image](/guides/unified-sensor-image/) has no shared default password. Each new sensor has a one-time setup code. Claim the sensor with that code and choose a password before you log in over SSH. To do this from the app, use the USB steps below. Do not try the older images' default password on a unified sensor.


## How to set up a new unified sensor over USB

The unified image gives the sensor a USB Ethernet link. The sensor sits at `198.18.42.1` on that link. The app reads the one-time setup code over the cable, so you don't type it.

1. Connect the sensor to the phone by USB. On a NanoPi, this is the USB-C port that also powers it. Power and adapters still matter; see [parts and wiring](/sensors/nanopi-zero2/build/).
2. Open **Devices**. The sensor appears as **Unidentified USB sensor** (or by its own name).
3. Open the setup form:
    - **iPhone:** tap the sensor's row. In **Add Discovered Device**, the **WLAN Commander USB setup** section reads the code by itself. It should say **New device detected on USB. Choose its password to finish setup.**
    - **Android:** tap **Add device** (**+**) and enter `198.18.42.1` as the **Host**. In the **WLAN Commander USB setup** card, tap **Read USB setup code**. It should say **Setup code read from USB. Choose a new password above.**
4. Enter a new **Password**. iPhone accepts 8 characters or more and recommends 12. Android requires 12 or more. This password also protects SSH and the sensor's website.
5. Tap **Set up device over USB**. When it finishes, you see **Setup complete. Save and connect to this device.**
6. Tap **Save** (iPhone) or **Save & test** (Android). The username is `wlanpi`.

You only claim a sensor once. If the sensor is already claimed, add it with the password you chose. Without a USB link, claim the sensor from its own website with the code from its SD card; see [the unified image guide](/guides/unified-sensor-image/).

## How to pair an ESP32-C5 over Bluetooth LE

1. Flash the board with the [firmware installer](/sensors/esp32-c5/flash/). Unplug it from the computer and power it again. The USB serial link is only for flashing. The phone talks to the board over Bluetooth.
2. Allow Bluetooth on iPhone, or **Nearby devices** on Android, when the app asks.
3. Open **Devices**. The board appears under **On This Network**. Its name depends on its firmware build.
4. Connect it. It needs no password:
    - On iPhone, tap the board's row.
    - On Android, tap **Connect** on its row.

   The app connects and opens the board's networks.
5. To read the board's firmware name, version and build ID, open its device detail. Look under **Firmware** (iPhone).

A board serves one phone at a time. If it is connected to another phone or computer, disconnect it there first. When you build a kit with several boards, power and label them one at a time. Then check that every board you plan to use is selected.

## How to check the radio before you start

A connection does not prove the sensor has the radio you need. In device detail, check the adapter, band, channel list and firmware. On iPhone, **Radio status** › **Country, driver and channels** lists which 5 GHz and 6 GHz channels are enabled. An ESP32-C5 cannot become a 6 GHz radio through any setting.

If a radio is missing on Linux, check that the adapter is detected and its driver and firmware loaded. If the radio is there but a band is not, check the country setting.

## Tips

- On iPhone, the phone and the sensor must be on the same Wi-Fi or LAN. Allow Local Network access when iOS asks. If you denied it, go to **Settings › WLAN Commander › Local Network**.
- Discovery uses mDNS, which often does not cross subnets or VLANs. Add the sensor by IP address in that case.
- Saved sensors are recognised by their identity, so a new address does not create a duplicate.

## If it doesn't work

| What you see | What to do |
|---|---|
| Nothing under **On This Network** | Check that you are on the same network and that Local Network access is on (iPhone). Then add the sensor by IP address. |
| Sensor listed but the connection fails | Check routing, client isolation and VLAN rules, the SSH service, your credentials, and that the sensor has finished booting. |
| **Connect the sensor directly by USB to read its setup code.** | The phone has no USB link in `198.18.42.x`. Check the cable, adapter and power, then reopen the form. |
| An ESP32-C5 never appears | Power the board. Disconnect it from any other phone or computer. On Android, tap **Refresh**, which restarts the Bluetooth scan. |
| The connection drops during work | Restore power and the network, then reconnect in **Devices**. An ESP32-C5 stops when the link drops. Do not assume a capture kept running; check the file's duration and timing. |

## Related

[Unified sensor image](/guides/unified-sensor-image/) · [ESP32-C5](/sensors/esp32-c5/) · [Compatibility](/sensors/compatibility/) · [Troubleshooting](/guides/troubleshooting/)