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My old college roommate moved into an apartment above mine. He has his own Internet via cable and I have mine. I am trying to include his machine as part of my workgroup/homegroup LAN network in Windows 7 without me sharing his Internet Connection or him sharing mine. But we'd like to be able to access each others files like music and tv-shows, we also work together in a graphics firm so I'd like the ability to transfer large PSD's over CAT5. Might also try video gaming. Basically I'm seeking a physical connection, wireless is not an option.

Is that possible? Can it be done using one router or do I have to use two, one for each machine and then connect the routers? Reason I ask is he's connected straight to the modem, I'm connected through a router.

Thank you.

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does each system have a ethernet connection to spare? – Journeyman Geek Jul 3 '11 at 23:38
Use a switch, its cheaper than a router, unless you have a freebie router. No you only need one switch or router. – Moab Jul 3 '11 at 23:50
or to connect the boxes directly - assuming there's jacks to spare. – Journeyman Geek Jul 4 '11 at 0:12
up vote 4 down vote accepted

There are lots of ways to do this, depending on how much you want to spend, how much security you want to put in place between your network and his machine, and whether or not you want to plan for the day when he has more than just the one machine on his network.

For now, if you want to minimize costs and aren't too worried about security, you would add a second network card to his machine (if it doesn't already have a spare) and connect that card into a spare switch port on your network. Then configure his second network card to have a static IP address on your home network, but don't tell the second network card about your default gateway. Without knowing about your default gateway, his OS won't try to get out to the Internet via your network.

Don't turn on any kind of Internet Connection Sharing (NAT, or any kind of bridging/switching or IP forwarding) and his machine won't pass traffic from your network onto his Internet connection.

So basically, make his machine multi-homed on the two networks, but not acting as a gateway, and let it think your network is a just a stub network with no off-subnet connection. All the machines on your network will think his machine is just another machine on your network, and they won't have a way to go "through" his machine to get to his Internet connection.

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This is probably the fast and painfree method. – surfasb Jul 4 '11 at 2:51
You could do this with a wireless card, too, which is probably a lot easier than getting cat5 run to the apartment above you. Same rule: just make sure there's no default gateway for the wireless card. Also, make sure your network and his network use different subnets. If you're both on, you'll have a hard time making this work. – Joel Coehoorn Jul 4 '11 at 3:54
Thank you very much Spiff! – Andy Hassan Jul 17 '11 at 19:52

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