HowTo auto connect your Linux to the German Wifi on ICE trains

wifionice

#!/bin/bash

# change the next line to match your wifi device and put this file in /etc/NetworkManager/dispatcher.d/ and make it executable

WIFI_DEVICE=wlp3s0

IF=$1
STATUS=$2


if [ "$IF" == "$WIFI_DEVICE" ] && [ "$STATUS" == "up" ] && [ $(iwconfig $WIFI_DEVICE | grep -c "ESSID:\"WIFIonICE\"") ]
then
        curl 'http://www.wifionice.de/de/' -H 'Host: www.wifionice.de' -H 'User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:58.0) Gecko/20100101 Firefox/58.0' -H 'Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8' -H 'Accept-Language: en-US,en;q=0.5' --compressed -H 'Referer: http://www.wifionice.de/' -H 'Content-Type: application/x-www-form-urlencoded' -H 'Cookie: csrf=42' -H 'Connection: keep-alive' -H 'Upgrade-Insecure-Requests: 1' --data 'login=true&CSRFToken=42&connect='
fi

First I wanted to get a valid CSRF token first by requesting the main page and extract it. Turns out this is not even necessary as long as the submitted token and the cookie are the same. Currently the captive portal server does not seem to remember the token it gives out.
In case that changes:

CSRF=$(curl -s 'http://www.wifionice.de/de/' | grep "CSRFToken" | sed -n '/CSRFToken/s/.*name="CSRFToken"\s\+value="\([^"]\+\).*/\1/p')
curl 'http://www.wifionice.de/de/' -H 'Host: www.wifionice.de' -H 'User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:58.0) Gecko/20100101 Firefox/58.0' -H 'Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8' -H 'Accept-Language: en-US,en;q=0.5' --compressed -H 'Referer: http://www.wifionice.de/' -H 'Content-Type: application/x-www-form-urlencoded' -H "Cookie: csrf=$CSRF" -H 'Connection: keep-alive' -H 'Upgrade-Insecure-Requests: 1' --data "login=true&CSRFToken=$CSRF&connect="

Works perfectly!