WiFi-/WLAN-Authentication at T-Mobile Hotspots (ICE Train) 
At the moment I take the ICE train of Deutsche Bahn twice a week. The particular train does offer Internet-Connection in cooperation with T-Mobile. The authentication is done via a captive portal and one needs a T-Mobile Hotspot Account, which is part of many Deutsche Telekom and T-Mobile products.
The usability of the captive portal sucks a little, as the browser does not save your credentials. So I captured the https-communication via Firefox liveheaders extension, extracted what's needed for authentication and wrote a little bash script to simplify the logon :-) It's free, public domain, so use it if you like. Keep in mind that the script does accept the terms of use (AGB) automatically!
Simply start it like this:
shell$ wlan-auth.sh yourlogin yourpass
If you use wicd as WiFi-Manager, you can also make the script run automatically if wicd connects to the T-Mobile_ICE Hotspot :)
And here is the wlan-auth.sh script:
#!/bin/sh
HSUSER=$1
HSPASS=$2
echo
"You accepted the terms of use (AGB)!";
if [ -e /tmp/tmobilehotspot-cookie ]; then rm /tmp/tmobilehotspot-cookie; fi
curl -c /tmp/tmobilehotspot-cookie \\
-F username=${HSUSER} \\
-F password=${HSPASS} \\
-F strAGB=AGB \\
-F strHinweis=Zahlungsbedingungen \\
-F x=48 \\
-F y=3 \\
https://hotspot.t-mobile.net/wlan/index.dowhile (
true );
do
curl -b /tmp/tmobilehotspot-cookie
https://hotspot.t-mobile.net/wlan/index.do > /dev/
null
sleep 300
done
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