Nearly all you need to know is available here:
http://www.geisterstunde.org/drupal/?q=osx_routing
All I found is that $BUNDLE refers to /System/Library/SystemConfiguration/Kicker.bundle/ and the script should go in $BUNDLE/Contents/Resources - not $BUNDLE/Resources (the paths are a little mixed in the original article).
The following dialog appeared when I got to work this morning (where I connect via wired ethernet rather than wifi). I feel that someone has not really understood the concept of wifi security:
Just a quick note.
If you configure the mac's HTTP proxy under network system settings to point to a squid server on your local network - then whatsmyip.net et al return your internal IP (in my case a 192.168.1.x one) - instead of the real external address.
Very confusing when you can't work out how an internal IP is getting out there - it isn't.
Could well be the same (in fact I expect it would be) for windows, linux too.
Want to get rid of lots of annoying adverts? Modify your hosts file - here's the link: