Host a Wi-Fi hotspot with a Raspberry Pi

Choose the right Raspberry Pi

The faster your Raspberry Pi, the better performance you’ll get. For this tutorial, we’ll be using a Raspberry Pi 4 2GB.

It’s a good idea to choose a Raspberry Pi with a built-in Wi-Fi module, because you’ll need two Wi-Fi devices to host your own hotel Wi-Fi hotspot: one to connect to the hotel network, and one to broadcast a network to your other devices.

Choose the right USB Wi-Fi adapter

Most USB Wi-Fi adapters with Linux driver support should suffice.

For this tutorial, we used a 802.11 b/g/n 2.4GHz adapter built around the MediaTek MT7601U chipset.

Connect via SSH

Open a terminal session on your usual computer. To access your Raspberry Pi via SSH, run the following command, replacing <username> with the user name you chose in Imager:

$ ssh <username>@pi-hotspot.local

$ ssh <username>@pi-hotspot.local
The authenticity of host 'pi-hotspot.local (fd81:b8a1:261d:1:acd4:610c:b069:ac16)' can't be established.
ED25519 key fingerprint is SHA256:s6aWAEe8xrbPmJzhctei7/gEQitO9mj2ilXigelBm04.
This key is not known by any other names
Are you sure you want to continue connecting (yes/no/
[fingerprint])? yes
Warning: Permanently added 'pi-hotspot.local' (ED25519) to the list of known hosts.

<username>@pi-hotspot.local's password:
Linux pi-hotspot 6.1.21-v8+ #1642 SMP PREEMPT Mon Apr  3 17:24:16 BST 2023 aarch64

The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
Last login: Tue Oct 24 09:41:00 2023
<username>@pi-hotspot:~ $

When asked for your password, use the password you created in Raspberry Pi Imager.

Find your USB Wi-Fi adapter

First, we need to find the USB adapter. Run the following command to identify Wi-Fi devices with the Network Manager CLI:

$ nmcli device

You should see output similar to the following:

DEVICE         TYPE      STATE                   CONNECTION
wlan1          wifi      connected               Example Wi-Fi
lo             loopback  connected (externally)  lo
wlan0          wifi      disconnected            --
p2p-dev-wlan0  wifi-p2p  disconnected            --
eth0           ethernet  unavailable             --

In the above output, the USB Wi-Fi module, wlan1, is connected to a Wi-Fi network named "Example Wi-Fi". The built-in Wi-Fi device, wlan0, is not currently in use, so the state currently reads "disconnected".

If your Raspberry Pi has a built-in Wi-Fi module, it should show up by default as wlan0. The first Wi-Fi module you connect should show up as wlan1, and subsequent adapters will display as wlan2, wlan3, and so on. Depending on your specific configuration, your Raspberry Pi might connect to your network using either the USB adapter or the built-in Wi-Fi module.

Create hotspot network

Next, we’ll use the built-in Wi-Fi module to broadcast a hotspot network. Run the following command to create a hotspot, replacing the <hotspot name> and <hotspot password> placeholders with a hotspot name and password of your choice:

$ sudo nmcli device wifi hotspot ssid <hotspot name> password <hotspot password> ifname wlan0

After creating the hotspot network, your hotspot should automatically become active.

Next, connect to the hotspot Wi-Fi network from your usual computer. Look for a network with an SSID matching the hotspot name you chose in the previous step. Use the password you also provided in that step to authenticate.

Then, connect to your Raspberry Pi using SSH:

$ ssh <username>@pi-hotspot.local

And run the following command to view your current connections:

$ nmcli connection

You should see output similar to the following:

NAME       UUID                                  TYPE      DEVICE
Hotspot    69d77a03-1cd1-4ec7-bd78-2eb6cd5f1386  wifi      wlan0
lo         f0209dd9-8416-40a0-971d-860d3ff3501b  loopback  lo
Ethernet   4c8098c7-9f7d-4e3e-a27a-70d54235ec9a  ethernet  --
Example 1  f0c4fbcc-ac88-4791-98c2-e75685c70e9f  wifi      --
Example 2  9c6098a7-ac88-40a0-5ac2-b75695c70e9e  wifi      --

The connection named Hotspot represents your new hotspot network. The Example 1 and Example 2 connections above represent saved Wi-Fi connections which are inactive.

Configure hotspot network

Let’s configure your hotspot network to automatically broadcast whenever your Raspberry Pi boots. When your Raspberry Pi boots, it starts whichever connection has autoconnect enabled with the highest priority. To ensure that your hotspot always starts on boot, we’ll enable autoconnect for the hotspot and configure a priority higher than any other connection.

Re-run the nmcli connection command above and copy the UUID for your hotspot network from the table. Then, run the following command to view connection properties for your hotspot network, replacing the <hotspot UUID> placeholder with the UUID for your hotspot:

$ nmcli connection show <hotspot UUID>

The output will contain a lot of properties that describe your hotspot network. But we’re only interested in the following two properties for now:

connection.autoconnect:                 no
connection.autoconnect-priority:        0

Run the following command to change the priority and autoconnect properties for your hotspot, replacing the <hotspot UUID> placeholder with the UUID for your hotspot that you copied to your clipboard before:

$ sudo nmcli connection modify <hotspot UUID> connection.autoconnect yes connection.autoconnect-priority 100

If your command executed successfully, we should see the following new values for those properties when we re-run nmcli connection show <hotspot UUID>:

connection.autoconnect:                 yes
connection.autoconnect-priority:        100

Configure connection portal

Next, let’s configure a portal website that allows you to easily connect your Raspberry Pi to a hotel Wi-Fi network from a browser.

Install the following tools:

$ sudo apt install python3-flask

Then, run the following command to make a directory where we can create our portal, called wifi-portal:

$ mkdir ~/wifi-portal

Then, navigate into the portal directory:

$ cd ~/wifi-portal

Open app.py in the portal directory, which contains the logic for the portal website:

$ sudo nano app.py

Copy and paste the following code into app.py:

from flask import Flask,request
import subprocess

app = Flask(__name__)

wifi_device = "wlan1"

@app.route('/')
def index():
    result = subprocess.check_output(["nmcli", "--colors", "no", "-m", "multiline", "--get-value", "SSID", "dev", "wifi", "list", "ifname", wifi_device])
    ssids_list = result.decode().split('\n')
    dropdowndisplay = f"""
        <!DOCTYPE html>
        <html>
        <head>
            <title>Wifi Control</title>
        </head>
        <body>
            <h1>Wifi Control</h1>
            <form action="/submit" method="post">
                <label for="ssid">Choose a WiFi network:</label>
                <select name="ssid" id="ssid">
        """
    for ssid in ssids_list:
        only_ssid = ssid.removeprefix("SSID:")
        if len(only_ssid) > 0:
            dropdowndisplay += f"""
                    <option value="{only_ssid}">{only_ssid}</option>
            """
    dropdowndisplay += f"""
                </select>
                <p/>
                <label for="password">Password: <input type="password" name="password"/></label>
                <p/>
                <input type="submit" value="Connect">
            </form>
        </body>
        </html>
        """
    return dropdowndisplay


@app.route('/submit',methods=['POST'])
def submit():
    if request.method == 'POST':
        print(*list(request.form.keys()), sep = ", ")
        ssid = request.form['ssid']
        password = request.form['password']
        connection_command = ["nmcli", "--colors", "no", "device", "wifi", "connect", ssid, "ifname", wifi_device]
        if len(password) > 0:
          connection_command.append("password")
          connection_command.append(password)
        result = subprocess.run(connection_command, capture_output=True)
        if result.stderr:
            return "Error: failed to connect to wifi network: <i>%s</i>" % result.stderr.decode()
        elif result.stdout:
            return "Success: <i>%s</i>" % result.stdout.decode()
        return "Error: failed to connect."


if __name__ == '__main__':
    app.run(debug=True, host='0.0.0.0', port=80)

Press Ctrl+X, then Y, and finally Enter to save the edited file with nano.

Next, let’s configure your Raspberry Pi to automatically run the Wi-Fi portal after boot. Run the following command to open your cron tab, a Linux scheduling tool:

$ crontab -e

Enter 1 to use the nano text editor to edit your cron schedule. Then, add the following line to the file, replacing the <username> placeholder with your Raspberry Pi admin account username:

@reboot sudo python3 /home/<username>/wifi-portal/app.py

Press Ctrl+X, then Y, and finally Enter to save the edited file with nano.

And enter the following command to reboot your Raspberry Pi:

$ sudo reboot

You’re now ready to connect to any hotel Wi-Fi network!