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I have a wi-fi network running off of an unlocked 2Wire 2701HG-x modem (user guide). Question: How can I publicly share it? Can I create two separate networks, one for myself (password-protected), and one unsecured (public, with limited bandwidth and/or speed) for all to use? Where do I start? Can I install special software on the router? Purchase special hardware?

Any pointers are highly appreciated. Thank you.

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Look for a Guest mode maybe? – francisswest Oct 24 '12 at 18:03
It might be possible to do what you want to do, but will likely require a separate wifi radio for the second radio (addon hardware; no idea if it's even feasible), as well as a good active queue management algorithm in the kernel for traffic shaping. Much easier to connect up a downstream router over ethernet and set that up as the "public" router. – allquixotic Oct 24 '12 at 18:04
@allquixotic Reading a similar question which also suggest using routers. Any idea of the steps? I'm really quite clueless when it comes to networking, although I could follow a good tutorial/manual. – dalbaeb Oct 24 '12 at 18:08
You just buy another router, and plug it into your existing router on a free ethernet port, and your "downstream" router will create its own NAT private subnet and get its own IP address from the upstream router's DHCP and route all DNS requests upstream and forward packets as if the router were "a computer" connected to the upstream router. Then just configure the downstream router without any security on the wifi. Note, you could also use an Access Point, which provides the wifi functionality but delegates the IP masquerading upstream, so you don't have a NAT within a NAT. – allquixotic Oct 24 '12 at 18:23
Also you might want to read up and really understand the OSI model, in particular the difference between a Layer 2 switch and a Layer 3 switch. Once you "get" that, you'll realize that an access point (equivalent of an ethernet hub) is a Layer 2 switch, and a "router" that does NAT is a Layer 3 switch. You really only need one layer 3 switch. You can still traffic shape the IPs being routed through the AP. – allquixotic Oct 24 '12 at 18:24

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