pass flag from server to client to script

[Carl Karsten]

I am trying to figure out how a script can detect if a laptop is on 'my' network 
or somewhere else.

The plan is to un/mount nfs mounts, flip proxy settings, apt-get upgrade, maybe 
even sync some data.

The trick is figuring out when the laptop has transitioned from 'out there' to 
'in here.'

The hope is to set something in dhcpd.conf like network-id='garblygookUUID' that 
  can be sent to the client that can somehow be tested for in the script.  I am 
guessing this is outside the dhcp spec, but may be a feature of ics's client.

Carl K