IP Observer provides you with a way to observe your assigned IP adress also behind a internet router and give a new adress to people by email. The assigned IP adress from yor privider changed every day. Also at Flatrates there is a cut of. So you can´t access to your computer from outside without knowing the current IP. IP Observer is emailing your the current IP.IP Observer is sending a request over Port 80 to Leicht.info Webserver like a browser and get the REMOTE_ADDR. So it´s possible to get the IP also on firewalled connections.