raspi-wifiselect

Imagine a Raspi-based wifi-enabled appliance, headless, just add power. When you bring it to a friend, how can you include it in the Wifi? How to add the password to it? Because obviously your friends use PSK/WPA2 on their wifi, otherwise they wouldn't be your friends. And naturally they share it with you. But how to share it with your raspi?

Manual Way: SD Card

• open the appliance and remove the SD card
• use a computer with SD card reader and extfs4 support (e.g. laptop with Linux live CD)
• use the standard commandline way of adding a wifi network on Raspbian: scan for available networks, call wpa_passphrase with the SSID and enter the password, then add it's output to the wpa_supplicant.conf file

iwlist wlan0 scanning|grep ESSID
wpa_passphrase <SSID> >> /etc/wpa_supplicant/wpa_supplicant.conf

• re-insert SD card into the Raspi and close the appliance

Nicer Way: USB Stick

• Preparation (once): Set up the wifiselect.js helper using the below instructions
• attach USB stick containing a text file /raspi/wifi.txt containing a line 'scan'
• wait ~30sec, unplug it and plug it into any computer with USB port and a text editor
• the /raspi/wifi.txt file now contains a list of found WLANS. Add the password into the one to be used
• Safely unplug the USB stick (otherwise Linux might complain and refuse to auto-mount it?)
• attach USB stick and wait ~30sec before unplugging again
• if successful, Raspi should now appear in Wifi and has it's DynDNS set correctly
• otherwise, look into files /raspi/stdout_wifi.txt and /raspi/stderr_wifi.txt on the USB stick

Alternative: Tethering Hotspot

• TODO: this is not implemented yet
• Idea: create a Wifi hotspot using smartphone tethering (only works if smartphone has Internet, e.g. won't work outside Germany w/o data roaming), then select SSID & provide password via a hosted webpage
• Available
  • script is running when network connectivity is added if it is placed in /etc/network/if-up.d/ (really? didn't work for me, needed to add it to /etc/network/interfaces explicitely)
  • some supports already included in wifiselect.js, but not finished
  • Smartphone Wifi configured in /etc/wpa_supplicant/wpa_supplicant.conf, with priority=1 (assuming all other networks have higher priority assigned, this will only be used if no other connection is available)
• Missing
  • define protocol between wifiselect.js and webpage (probably JSON, what fields?)
  • create PHP(?) server page on some server you happen to have access to, needs database (or textfile?) backend and admin UI
  • enhance wifiselect.js to actually do the needful

Alternative: MS Windows 'Export Network Config'

• Windows offers to export known network configurations to an USB stick
  • The SSID and plaintext password are in an XML file called SMRTNTKY/WSETTING.WFC, other files will be added as well (AUTORUN.INF, setupSNK.exe and folder SMRTNTKY with some files in it)
• On windows, open the properties of the wireless network, tab 'Connections', and select "Copy this network profile to a USB flash drive"
• plug the USB stick into the Raspi and wait ~30sec

Push-Button WPS

• TODO: not implemented yet
• needs a router which supports Wifi Protected Setup, even though it's insecure
• see Headless wifi via push button WPS

Wifiselect Script Setup

• install node: apt-get install node
• clone this repository onto the Raspi, e.g. to /root/bin and ensure the scripts are executable
• in the same directory, install the node modules:

npm install q fs path request child-process-promise xml2js

• add a rule to UDEV, e.g. in a file /etc/udev/rules.d/70-persistent-usb_autorun.rules

SUBSYSTEM=="block", KERNEL=="sd*1", ACTION=="add", SYMLINK+="usbstick%n", RUN+="/root/bin/raspi-wifiselect/usb_autorun.sh %E{ID_FS_LABEL} %E{ID_FS_UUID}"

this triggers on adding of a new device matching "sd*1" (e.g. sda1), creating a symlink to ensure it's available at the constant name /dev/usbstick1 (1 = partition number), then runs the autorun script, which will access it

• Security Note: The autorun.sh feature will run a user-supplied script with root permissions! It's advised to disable this part of usb_autorun.sh
• Links:
  • Automatically mount USB external drive with autofs
  • Automount USB drives with no GUI requirement (halevt replacement)
  • Autostart script from USB device with Udev
• install autofs

apt-get install autofs

* add in file */etc/auto.master*

/media/auto   /etc/auto.ext-usb --timeout=10,defaults,user,exec,uid=1000

this will create /media/auto and automounts when accessed, with umount after 10sec inactivity, and some existing, irrelevant user (uid=1000) * create file /etc/auto.ext-usb

usbstick            -fstype=auto           :/dev/usbstick1

now /media/auto/usbstick will automount after it's being accessed, e.g. by the usb_autorun.sh script, and then being umounted again

TODO

• not usable for hidden SSIDs. Perhaps look at this script for inspiration?
• create a separate config file, which isn't in the repository, to password-protect the autorun.sh script,
• add support for Raspi A+, which has only one USB slot. The current script requires to have the USB stick and the Wifi available at the same time.