James, take a look at
http://www.astaro.org/astaro-gateway...ight=designing first.
The fundamental problem is that a knowledgeable user can sneak past the Profile for him to get to the default one. I would ping to check that another IP is available, then change the properties of my network connection to use that IP instead of DHCP. You would have to track me down by MAC address... if you could devine it
Cheers - Bob