WiFi AP - HostApd

Creating a WiFi hotspot on a device running Linux involves configuring the built-in wireless adapter to act as an access point. Below are general steps to achieve this using the hostapd software:

Prerequisites:

Ensure that your device has a compatible wireless adapter. You may need an external USB WiFi dongle if the built-in WiFi doesn't support the necessary features.
Make sure your device is running a Linux distribution with package management. Debian is a popular choice.

Step 1: Install hostapd and dnsmasq

sudo apt-get update
sudo apt-get upgrade -y 
sudo apt-get install hostapd dnsmasq

Stop Services:

sudo systemctl stop hostapd
sudo systemctl stop dnsmasq

Configure Static IP for the Access Point:

Edit /etc/dhcpcd.conf and add the following lines at the end:

interface wlan0
static ip_address=192.168.4.1/24
nohook wpa_supplicant

Configure dnsmasq:

Create a new configuration file /etc/dnsmasq.conf and add:

Configure Hostapd:

Create a new configuration file /etc/hostapd/hostapd.conf :

Here can find more information about the hostapd configuration

https://web.mit.edu/freebsd/head/contrib/wpa/hostapd/hostapd.conf

The hw_mode parameter can take one of the following values:

a: Specifies 5 GHz (802.11a)
b: Specifies 2.4 GHz (802.11b)
g: Specifies 2.4 GHz (802.11g)
ad: Specifies 60 GHz (802.11ad)
n: Specifies 2.4 GHz or 5 GHz (802.11n)
ac: Specifies 5 GHz (802.11ac)

Update Hostapd Configuration:

Edit /etc/default/hostapd and update the line:

Start Services:

Enable Services to Start on Boot:

Reboot:

After rebooting, your device should be broadcasting a WiFi hotspot with the specified SSID and password. You can connect to it using a device and should be able to access the internet through the device.

Adjust the configurations (SSID, password, IP range, etc.) according to your preferences.

Please note that these steps provide a basic setup, and additional configurations may be needed depending on your specific requirements and the Linux distribution you are using.