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Here's the basic setup of my network

enter image description here

In this diagram:

1: The internet
c: cable
2: Wireless router
w: wireless connection
3: A win7 box with internet connection sharing enabled
4: A wireless router, but I'm only using its LAN capabilities to connect box 5 to the internet.
5: A win7 box, the computer I'm using to make this post. So its internet works just fine.

Now if I'm on box 5, and I ping 192.168.1.1, I hit 4. If I'm on box 3 and I ping 192.168.1.1, I hit 2. Now obviously box 3 does not think 4's IP address is 192.168.1.1, or I wouldn't be able to connect to the internet.

Okay, now that you know as much as I do about my network, here's my question:

If I was on box 3, how would I determine the IP address of 4?

Basically I'm running a webserver on box 5 and want to access this webserver on box 3 and other boxes. So that's the end goal. If there's other information there that can help, I'd appreciate it.

Thanks!

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migrated from serverfault.com Apr 6 '12 at 1:03

This question came from our site for professional system and network administrators.

6  
+1 for the superb network diagram. :) –  SmallClanger Apr 5 '12 at 16:37
1  
Honestly, I have no clue what the hell you are getting at, but you get a +1 for the excellent mspaint diagram. –  MDMarra Apr 5 '12 at 16:43
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Why do you need 2 routers? Why isn't just 1 router enough? I think that would make things more easier. –  Guanidene Apr 5 '12 at 16:47
    
I was hoping it was something to do with not wanting to run wire from the point where his cable connection comes in to his computers... –  Bart Silverstrim Apr 5 '12 at 16:50
    
@Guanidene I need two routers because box 5 won't connect wirelessly, so I need to use a LAN to connect it. Unfortunately, I only have my other router, I don't have a simple hub or switch to plug it in to. –  corsiKa Apr 5 '12 at 16:58

3 Answers 3

You appear to have created a monstrous multiple-NAT, multiple-DHCP-server situation which can be resolved as follows:

  1. Wireless router #4 needs to function only as an access point. Even if you are only using the switch ports, it is going to answer DHCP requests and try to assign IP addresses. You need to log into its web interface and find "Bridge Mode" or a "Join a wireless network" mode or "Access Point Mode" instead of the default full-service routing mode. This device should not be doing anything other than connecting its switch ports to the wireless network. Under no circumstances should you plug anything into the WAN port on wireless router #4.

  2. Turn off Internet Connection Sharing on computer #3. There is no reason for that to be turned on. Your wireless bridge should be between the two access points, not between the first access point and one of your two computers.

  3. Depending on the make/model of your cable modem, it too may be providing NAT. If the WAN IP address on wireless router #2 is 10.x.x.x or 192.168.x.x or 172.(16-31).x.x then THAT device needs to be in bridge mode too. Otherwise leave it alone.

Goal: one device on your itty-bitty network provides DHCP and NAT. Not three or four.

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Well, it depends on your setup really.

If box 5 is on a different subnet to box 3, e.g.: Box 5 is on the IP range 192.168.1.* and Box 3 is on the range 192.168.2.*, what you need to do is setup routing on the wireless router to be able to send traffic between the two.

If on Box 3 your default gateway is setup to be box 2, you will need to add a static route to box 3 to tell you how to get to this address, e.g.: using the IP ranges above

route add 192.168.1.0 mask 255.255.255.0 192.168.2.1 METRIC 2

With the IP of the router on the 192.168.2.* range being 192.168.2.1. If the default gateway is the wireless router, you will not need to do this.

If, however, both of your boxes are on the same subnet, you just need to change the wireless router to be in switch mode and you should see both on the same subnet.

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Sounds like you aren't using just the switch on your wireless router, you're using the uplink port somewhere, partitioning off part of the network. Put your computers on the switch ports alone and they'll be in the same subnet and see each other properly.

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Box 3 is plugged into the uplink of router 4. Are you saying if it wasn't plugged into the uplink that it would work like a normal switch? –  corsiKa Apr 5 '12 at 16:59
    
A SOHO switch, yes. The uplink is meant to connect to a public WAN, like the Internet or upstream router. –  Bart Silverstrim Apr 5 '12 at 17:02
    
I tried doing that, but it didn't work. It just broke all connections. :( –  corsiKa Apr 5 '12 at 17:06
    
The wireless part should still see your other wireless router (I'm assuming you bridged them somehow.) Or are you wireless from your cable router to the one Win7 computer, and that's why you're using connection sharing? Because if so, you don't want to do that. –  Bart Silverstrim Apr 5 '12 at 17:17
    
While this is all kind of shaky, you'd want the wireless routers to bridge each other. Then use the switch part for your PC's. Otherwise you're double-natting the one machine. –  Bart Silverstrim Apr 5 '12 at 17:18

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