No need, other than the local 192.168.x.y network. We do indeed disconnect them and I should have mentioned that. I agree with sk8rsdad's comment about Linux. Apple started off as a derivative - many terminal commands are still the same, I think. And Windows is edging that way. Perhaps it's time to look into it as a development environment...Just curious - what's your need for these computers to talk to the internet at all during a tech period/production? If it were me, I'd be unplugging the network entirely. Let them do updates/etc after the run is over. If you have a permanent run, allow internet access for updates only on Mondays (or whatever day you're dark) and then do a full test after dumping the internet connection again. Any resources should be stored locally anyways in the event of internet failures, etc. Food for thought, or for future readers.