Sharing Internet, but Not Network

[ThisDude]

Hi everybody. Long time lurker (have usually found all of my answers by searching old threads), but today, I'm asking my first question.

The scenario: When my neighbor was over for dinner last week, he remarked how he liked my HTPC-no cable option, but could never live without cable (even if it is expensive). I told him I don't really save that much money, because the internet isn't that much cheaper when purchased stand alone.
So he suggested we should look into sharing his internet. Now, I'm not sure if I'm actually going to do this (I think there are performance and legal issues), but I'm still interested in trying it, for my own education.

My only concern is keeping my network separate from his computers--I run a file server, my htpc, personal computers, etc. I believe this will work: use client mode (as opposed to client bridged) mode in my DDWRT-enabled router (the client router), so that all of the devices that hook into my router will exist on a separate subnet, and that subnet will be inaccessible from his devices (because of the firewall in my router, right?--do I have to set that up?). As for getting wifi in my house, a second router connected to the client router's lan port (to the AP's wan port) can be used as an access point.

Do I have this right? Is there an easier way to do this?

 

[Fardringle]

While I can understand the reasoning behind wanting to do this (saving money is always nice), what you are trying to do is against the TOS of your ISP and most people here aren't going to help you break the rules since many of us work very hard to establish and maintain those rules in our own workplaces.

 

[ThisDude]

Thanks for the quick response.

FWIW, I agree with your general sentiment, and, as you'll see in my original post, I'd already expressed those concerns. At this point, it's more about learning principles for future use. For example, if I wanted to setup a guest network in my house (without the use of VLANs, I'm thinking a similar setup would work then. (Of course, if it's in my house, I'll probably use a wire to connect the two routers.

It's really a question of how subnets work, and if I understand them correctly.

 

[ch33zw1z]

Routers are layer 3 devices and will route traffic between subnets.

 

[ThisDude]

Routers are layer 3 devices and will route traffic between subnets.

Thanks for the input. Given that the router will route traffic across the two subnets, I'll need to setup the router's firewall to reject transmission across subnets then?

 

[ch33zw1z]

If that's even possible on a SOHO router, it may work.

I'm with Fardringle on this one, however. breaking TOS is not a good idea. Worst case, if caught, you both get blacklisted.