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Share internet access between two separate networks

Last response: in Networking
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October 20, 2011 10:22:52 PM

I want to share one broadband connection between network A 192.168.1.xxx and network B 192.168.0.xxx. Network A is SBS 2008 while B is Linux with static IPs.
October 21, 2011 12:18:32 AM

Since your typical consumer router can't be multi-home'd (i.e., support more than one network at a time), the easiest thing to do is use a second router, then chain them, one behind the other.

[modem](lan)<-- wire -->(wan)[router 192.168.1.x](lan)<-- wire -->(wan)[router 192.168.0.x]

Pretty simple, actually. Of course, which router supports which network can have both security and cross-network access issues. But since you provided so few details, it’s hard to say what makes the most sense. All I can contribute is *a* configuration that establishes workable connectivity.

Just to illustrate, in the example above, clients of 192.168.0.x are double NAT’d. Also, clients of 192.168.0.x can see/access the 192.168.1.x network upstream, while conversely, clients of 192.168.1.x can’t see/access the 192.168.0.x network. Plus, clients of the 192.168.1.x network can potentially “spoof” clients of the 192.168.0.x network.

IOW, configuration is one thing, but what any given configuration means in terms of these types of issues is another, and can only be addressed by asking and answering the right questions. If you were indeed concerned about spoofing, for example, you would really need three routers in a Y configuration.

[router 192.168.0.x] (wan)<-- wire -->(lan)[router 192.168.99.x](lan)<-- wire -->(wan)[router 192.168.1.x]

Of course, the WAN port of the 192.168.99.x network is connected to the modem.

Hope that helps.


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December 12, 2011 3:05:52 AM

Interesting instruction but I'm missing some ip's or configuration instruction

In my case I have
FIOS > [1-Router 192.168.1.x] > [2-Router 192.168.10.x] >[3-Router 192.168.11.x]
(My PC's, Wii on 3-Router can't see my NAS Drive from 2-Router 'LAN"]

What I'm missing in my router setup?
will it help if I assign all WAN IP to: 192.168.1.1 ???
Q: What WAN ip I can assign?

Note: [2-Roter have dynamic on from 100-254]

I have [3-router for WiFi] this way my IP can't conflict if new DHCP come to network

My Goal is to make [Router 3 - 192.168.11.1 - 254] access NAS Drive on [Router 2 192.168.10.1 - 254] and reverse
m
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December 13, 2011 2:44:39 PM

ottoag said:
Interesting instruction but I'm missing some ip's or configuration instruction

In my case I have
FIOS > [1-Router 192.168.1.x] > [2-Router 192.168.10.x] >[3-Router 192.168.11.x]
(My PC's, Wii on 3-Router can't see my NAS Drive from 2-Router 'LAN"]

What I'm missing in my router setup?
will it help if I assign all WAN IP to: 192.168.1.1 ???
Q: What WAN ip I can assign?

Note: [2-Roter have dynamic on from 100-254]

I have [3-router for WiFi] this way my IP can't conflict if new DHCP come to network

My Goal is to make [Router 3 - 192.168.11.1 - 254] access NAS Drive on [Router 2 192.168.10.1 - 254] and reverse


What you’ve described as your goal (“…to make [Router 3 - 192.168.11.1 - 254] access NAS Drive on [Router 2 192.168.10.1 - 254] and reverse”) is too narrow. I could just tell you to drop the firewall on router 3 to allow access from router 2’s network, but it begs the question why you’re configured this way in the first place. What’s the BIG picture here? Why do you have so many routers, with so many networks? You obviously have something in mind, but it isn’t clear. Are you trying to prevent access to resources from one network to another? Do you need a separate guest network? Do you want to keep wireless users limited to internet access? Do you just need more LAN ports? IOW, describe it in plain english, then we’ll discuss the technical details to make it happen.

When I tresponded to the OP, it was my assumption he wanted/needed to keep the two routers/networks separated, but I didn’t delve any deeper. And as a result, I offered a Y configuration that did just that. However, it’s not clear to me that you want/need the same thing. In your case, you presumably have chained your routers over their respective wan ports.

FIOS >(wan) [1-Router 192.168.1.x](lan) > (wan)[2-Router 192.168.10.x](lan) >(wan)[3-Router 192.168.11.x]

There are very few circumstances in which the average consumer needs more than one network. In fact, more networks often cause the very kind of problems you’re experiencing, such as access problems across those networks due to firewalls. But you normally only need those firewalls when you consider the other network to be potentially hostile, such as when your primary router is connected to the ISP over the modem (since you don’t control the ISP’s network, it only makes sense to be suspicious and protect yourself from him and the greater Internet). But in your case, it’s not obvious that routers 2 and 3 should be considered similarly. That’s not to say you couldn’t make the case (e.g., you want to give Internet access to guests but not let them have access to the rest of your network). But without making that clear, it’s hard to say which configuration makes the most sense.

For example, assuming you DON’T need to keep these networks protected from one another, you could simply connect them LAN to LAN. You would also need to disable the DHCP servers on routers 2 and 3, and give them a unique static IP in the same network as the primary router.


FIOS >(wan) [1-Router 192.168.1.1](lan) > (lan)[2-Router 192.168.1.2](lan) >(lan)[3-Router 192.168.1.3]

As configured, routers 2 and 3 do NOT route (since that would require the use of their respective WAN ports, which remain UNUSED), but merely switched. You might do this, for example, if you needed more LAN ports for the primary router, and/or wanted to add another wireless AP.

It’s a helluva lot easier to manage the above configuration than trying to manage MULTIPLE networks as in your proposed configuration. Again, I’m not saying a case can’t be made, but I’ve seen far too many ppl do just what you’ve described when in fact it was completely unnecessary once their true goals were understood. And spend endless hours trying to debug it because they failed to fully understand the implications.
m
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December 15, 2011 3:25:08 AM

My goal is extend WiFi signal and avoid IP conflict when new device sign in
(router FIOS (1) stay in garage "prime - router modem" > Router 2 192.168.10.xxx stay on South side building have OPEN DNS filter > Router 3 192.168.11.xxx stay on North side on 2nd FL.
I do experience ip conflict when new gadget/PC is signing to LAN/WiFi this way i prefer to have router 2 and router 3 on separate network address.
Router 1 (FIOS) is use as modem (signal low, and 10/100) compare to other 2 routers is 10/100/1000 Dual-Band WiFi B/G/N. I have Cisco SR2024T 24 port 10/100/1000 Gigabit Switch.
My issue to split network "I do experience ip conflict when new gadget/PC is signing"

Thank you
m
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l
March 13, 2013 9:40:25 PM

eibgrad said:
ottoag said:
Interesting instruction but I'm missing some ip's or configuration instruction

In my case I have
FIOS > [1-Router 192.168.1.x] > [2-Router 192.168.10.x] >[3-Router 192.168.11.x]
(My PC's, Wii on 3-Router can't see my NAS Drive from 2-Router 'LAN"]

What I'm missing in my router setup?
will it help if I assign all WAN IP to: 192.168.1.1 ???
Q: What WAN ip I can assign?

Note: [2-Roter have dynamic on from 100-254]

I have [3-router for WiFi] this way my IP can't conflict if new DHCP come to network

My Goal is to make [Router 3 - 192.168.11.1 - 254] access NAS Drive on [Router 2 192.168.10.1 - 254] and reverse


What you’ve described as your goal (“…to make [Router 3 - 192.168.11.1 - 254] access NAS Drive on [Router 2 192.168.10.1 - 254] and reverse”) is too narrow. I could just tell you to drop the firewall on router 3 to allow access from router 2’s network, but it begs the question why you’re configured this way in the first place. What’s the BIG picture here? Why do you have so many routers, with so many networks? You obviously have something in mind, but it isn’t clear. Are you trying to prevent access to resources from one network to another? Do you need a separate guest network? Do you want to keep wireless users limited to internet access? Do you just need more LAN ports? IOW, describe it in plain english, then we’ll discuss the technical details to make it happen.

When I tresponded to the OP, it was my assumption he wanted/needed to keep the two routers/networks separated, but I didn’t delve any deeper. And as a result, I offered a Y configuration that did just that. However, it’s not clear to me that you want/need the same thing. In your case, you presumably have chained your routers over their respective wan ports.

FIOS >(wan) [1-Router 192.168.1.x](lan) > (wan)[2-Router 192.168.10.x](lan) >(wan)[3-Router 192.168.11.x]

There are very few circumstances in which the average consumer needs more than one network. In fact, more networks often cause the very kind of problems you’re experiencing, such as access problems across those networks due to firewalls. But you normally only need those firewalls when you consider the other network to be potentially hostile, such as when your primary router is connected to the ISP over the modem (since you don’t control the ISP’s network, it only makes sense to be suspicious and protect yourself from him and the greater Internet). But in your case, it’s not obvious that routers 2 and 3 should be considered similarly. That’s not to say you couldn’t make the case (e.g., you want to give Internet access to guests but not let them have access to the rest of your network). But without making that clear, it’s hard to say which configuration makes the most sense.

For example, assuming you DON’T need to keep these networks protected from one another, you could simply connect them LAN to LAN. You would also need to disable the DHCP servers on routers 2 and 3, and give them a unique static IP in the same network as the primary router.


FIOS >(wan) [1-Router 192.168.1.1](lan) > (lan)[2-Router 192.168.1.2](lan) >(lan)[3-Router 192.168.1.3]

As configured, routers 2 and 3 do NOT route (since that would require the use of their respective WAN ports, which remain UNUSED), but merely switched. You might do this, for example, if you needed more LAN ports for the primary router, and/or wanted to add another wireless AP.

It’s a helluva lot easier to manage the above configuration than trying to manage MULTIPLE networks as in your proposed configuration. Again, I’m not saying a case can’t be made, but I’ve seen far too many ppl do just what you’ve described when in fact it was completely unnecessary once their true goals were understood. And spend endless hours trying to debug it because they failed to fully understand the implications.


Im wanting to create a guest network so they have access to the internet but not to my other computers. This is my setup:
modem->wan router 1 (192.168.1.1) lan->wan router 2 (192.168.10.1). How do i route all traffic from the second router directly to the wan side of router one? Thanks

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