That device isn't really a hub at all, but actually a dedicated internet sharing device that also acts as a 4 port switch.
It shares the internet using NAT, and the device itself provides DHCP to the internal network. The device itself is the one interface that actually see's the Internet, and it shares that connection with the internal private network.
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Lephturn - Chief Trainer
A member of The Flying Pigs
http://www.flyingpigs.com "A pig is a jolly companion, Boar, sow, barrow, or gilt --
A pig is a pal, who'll boost your morale, Though mountains may topple and tilt.
When they've blackballed, bamboozled, and burned you, When they've turned on you, Tory and Whig,
Though you may be thrown over by Tabby and Rover, You'll never go wrong with a pig, a pig,
You'll never go wrong with a pig!" -- Thomas Pynchon, "Gravity's Rainbow"