Changes to external ip

Using Arduino Networking, Protocols, and Devices
6

Put this php script to a server on Internet with know ip:

<?php
print ('<'.$_SERVER['REMOTE_ADDR'].'>');
?>

And use something like this script to read the ip from there: http://bildr.org/2011/06/arduino-ethernet-client/

Now you just need to compare the new and old ip values.

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