This is a rip from the Ubuntu guide

  • Get a free dynamic IP account from one of the many providers. Here we will use DynDNS.
sudo apt-get install ddclient
  • Edit the configuration file /etc/ddclient.conf using you fevorite text editor (emacs, gedit, kedit or even vi)
sudo emacs /etc/ddclient.conf
  • Make it look like this:
# Configuration file for ddclient generated by debconf
# /etc/ddclient.conf
* Make sure that you use the web IP detection method.
* Specify your own user id instead of the place holder YourNameHere.
* Specify your own password instead of the place holder YourPasswordHere, make sure to surround it with single quotes.
* The last line should specify the hostname you registered with the dynamic IP service.
  • You can now start the ddclient daemon, or wait until your next reboot.
sudo /etc/init.d/ddclient start
  • The hostname you registered with your dynamic IP service should be updated. You can test it with the ping command:
Even if your laptop has a firewall that prevents pings the hostname should resolve to the IP of the network gateway that your laptop is connected to.
Now all that is left is for someone to steal your laptop…..