WiFi remote access and WPS daemon for Raspbian

This systemd service can toggle WiFi, SSH and DHCP on a Raspberry Pi from via a GPIO button. Additionally it can connect to an access point using WPS by long-pressing that same button. It can also detect and copy new wpa_supplicant.conf files from an USB stick to the proper system directory to reconfigure the WPA encryption.

If you find a bug or make an improvement your pull requests are appreciated.

License

All of this is under the MIT License.

Usage

Remote access toggle functionality

By default it waits for a 2-5s press of the F12 key from an input device to:

1. Either: Comment / uncomment the "dtoverlay=disable-wifi" entry in "/boot/config.txt" (default).
2. Or: Power up / down the WiFi device using iwconfig.

• Enable / disable the "ssh" systemd service.
• Enable / disable the "dhcpcd" systemd service.
• Reboot the RPi to apply the changes (option 1. needs a reboot).

With option 1. WiFi can be fully disabled. Option 2. only disables the device.

WPS connect functionality

By default it waits for a 5-8s press of the F12 key from an input device to:

• Enable WiFi if necessary(see above, might involve a reboot).
• Start looking for the strongest WiFi access point with WPS enabled and connect to that.
• Store the configuration for that AP.

WPA configuration file copy functionality

The daemon will watch for a path to become available (use usbmount to mount USB sticks automatically) with a wpa_supplicant.conf file in its base directory every 3s. It will then copy that file to the proper location on the file system (/etc/wpa_supplicant/wpa_supplicant.conf) if it differs from the current configuration and reboot the system. This way you can get a headless RPi onto new networks really quickly without WPS.

Build, configure, install

• Clone repo using git clone https://github.com/HorstBaerbel/remoteaccessd
• Navigate to the remoteaccessd folder, then:

mkdir build && cd build
cmake --config Release ..
make -j$(nproc)

Configuring

• Adjust the ExecStart= call in "remoteaccess.service" to your needs before installing. The command line options for the daemon are:

1. GPIO button input device, e.g. "/dev/input/event0"
2. Directory to watch for a "wpa_supplicant.conf" file, e.g. "/media/usb"
3. Optionally a method to toggle WiFi. Pass either "useOverlay" or "useIwconfig" to specify which method to use.
   • useOverlay: Modify the Raspberry Pi /boot/config.txt and add / remove dt-overlay=disable-wifi. This is the default if you pass no option
   • useIwconfig: Use iwconfig to control the WiFi device

The line should look something like this: ExecStart=/usr/local/bin/remoteaccessd /dev/input/event0 /media/usb useOverlay

By default the daemon plays audio via the aplay command (can be turned off). If you want to have multiple audio streams playing you will need to use the dmix plugin, otherwise the device is openend in exclusive mode and will block. See here how to set up ALSA to use dmix.

Installing

• Run installation: sudo make install

The daemon should now run. You can check its state with: systemctl status remoteaccess. The service starts relatively late in the boot process (after "basic.target"), so it might take couple of seconds after bootup until button presses or config files are detected.

Uninstalling

• Run deinstallation: sudo make uninstall

Additional information

How to add a GPIO button to your system

• Connect a normally-open / "NO" button to your RPi
• Add a button overlay to "/boot/config.txt": sudo nano /boot/config.txt and add:

# Toggle WiFi / SSH, KEY_F12
dtoverlay=gpio-key,gpio=23,label="wifi-toggle",keycode=88

This will create a GPIO button input device under /dev/input/eventX (connected to GPIO 23). You can find out what X is by running evtest, selecting a device number and trying the button. You can read more about device overlays here and about keycodes here.

An example wpa_supplicant.conf file

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
country=TWO_LETTER_COUNTRY_CODE

network={ 
ssid="ROUTER_SSID"
psk="WIFI_PASSWORD"
}

You can encrypt your password, so you don't need to store it in clear text using: wpa_passphrase ROUTER_SSID. The tool will prompt you for your WPA password and encrypt it. The use that string in the "wpa_supplicant.conf" file instead of the password, but WITHOUT quotation marks, e.g. psk=34985abcf4576e9.