First off, I am not a networking guy, but I have been given this problem to solve.

The problem: Our office wants to introduce another ADSL internet connection (making a total of 2). Each ADSL has a router, and the upper floor will use one connection, the other (lower floo) one will use the other for internet purposes. Now, we want to enable file sharing on the server. Since, the server is on the upper floor, and is only connected to one router connection, and the the down floor is to the other, we are on separate networks. The server is ubuntu, while the other computers on both floors are windows and macs. We need to be able store file on the server, from both the network at the upper floor (which is happenning now), and the lower floor. Is this possible, for the other network to upload files to the server? We donot want to use internet for file sharing as the speed is not good and will betray the purpose of getting another internet connection.

How should I go about getting this setup, if it is even possible?

  • Why are these separate networks? Do they not interconnect at all? Sep 4, 2012 at 6:39
  • @MichaelHampton. Because each ADSL line has to have a seperate router (with DHCP) and they get seperated (i m not sure). Is it possible to interconnect them two?
    – Dorje
    Sep 4, 2012 at 6:52

2 Answers 2


You can make your server a router between the two networks. You just need to have another NIC on the server and connect each NIC to one subnet. This way each subnet can access the server via the directly-connected NIC. You need also to make sure you are using two different IP ranges for the two subnets in both floors.

You can go further by enabling IP forwarding on the server and iptables if desired to specify the allowed traffic between the two subnets.

  • thank you, i seem to understand a bit of what your suggesting. I will give some more read (any links?), and test it out.
    – Dorje
    Sep 4, 2012 at 6:54
  • If you know how to configure the network interfaces, you don't need more than that. Then, simply make sure to connect each NIC to the appropriate subnet and PCs from subnet1 will reach the server using IP1 and PCs from subnet2 will reach the server using IP2.
    – Khaled
    Sep 4, 2012 at 7:00

I am assuming your two networks are on seperate subnets, if so, stick a network cable from each network in a Layer 2 Managed Switch or a Layer 3 switch, making sure this switch supports routing. Set a static route on each machine to the other subnet via the IP of the router, if it supports it, add this static route to the Routers handling your internet connection as I imagine these are set as your default gateway.

If the two networks are on the same subnet(, make sure there are no IP conflicts and stick an unmanaged switch between the two networks.

  • hmm, i will ask my boss about the switch supporting routing or not? I not into networking so this is a bit technical for me to understand but any links you can point me to..i am all for learning
    – Dorje
    Sep 4, 2012 at 6:57

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