Wi-Fi Access Point and Station Mode

Easily start and stop using your device as a wireless access point. Specifically designed to work with the host device's onboard Wi-Fi interface (wlan0).

Built for Raspberry Pi, but should work with other Debian-based systems running with compatible Wi-Fi hardware.

Usage

Usage:

    wifi-ap-sta {start,stop,status}

where:
    start  : use device as wireless access point.
    stop   : stop access point mode and restore previous configuration.
    status : display access point state and information.

Default Behaviour

By default, the access point's SSID is the hostname of the machine that runs the script combined with the serial number of the device. The passphrase is an 8-digit random number.

General AP mode/DHCP server configuration:

AP_SSID=$(hostname)
AP_IFACE=ap0
AP_MAC=99:88:77:66:55:44
WIFI_IFACE=wlan0
STATIC_IP_PREFIX=192.168.90
IFACE_IP=${STATIC_IP_PREFIX}.1
SUBNET_IP=${STATIC_IP_PREFIX}.0
SUBNET_MASK=255.255.255.0
DHCP_RANGE_START=10
DHCP_RANGE_END=50

Overriding default behaviour

Simply redefine the parameter you want to change in /etc/default/wifi-ap-sta, which is sourced by wifi-ap-sta.

This file is sourced in the main wifi-ap-sta script, so you can evaluate bash expressions to create dynamic results.

Steps

Start

• Enable wireless interface via rfkill if necessary
• Create a virtual network interface to be used by the access point

On bullseye and older:

• Patch system network configuration files (hostapd.conf, dhcpcd.conf and dhcpd.conf)
• Start access point service through hostapd
• Restart networking services

On bookworm:

• Create and start a new connection using nmcli

Stop

On bullseye and older:

• Stop hostapd access point service
• Restore patched networking configuration files

On bookworm:

• Stop and remove connection

Also:

• Remove virtual network interface
• Restart networking services

Station Mode: Things To Note

Even though the wireless interface is enabled, you may still need to configure it for it to work with wpa_supplicant. For example, in Raspberry Pi OS and derivatives you'll need to select your country during onboarding or set it manually using raspi-config.

How It Works

On bookworm, this application creates an access-point connection using the NetworkManager. On older distributions, this application makes use of hostapd and isc-dhcp-server to do this.

hostapd (host access point daemon) is a user space daemon software that can enable a network interface card to act as an access point and authentication server.

isc-dhcp-server (Internet Systems Consortium's - Dynamic Host Configuration Protocol - server) is a network service that enables host computers to be automatically assigned settings from a server as opposed to manually configuring each network host.

Constraints

This application is specifically developed to work on Raspberry Pi OS and derivatives, with some additional functionality to work with pi-topOS's DHCP server that is used for connecting to a pi-top [4] via the display cable (or connecting to a Pi via USB-OTG from the power connector).

As such, systemd and other core configuration is relied upon being present and largely unmodified. Unexpected behaviour may come from modifying the system state or running in a different environment.