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Help on configuring routing RRS feed

  • Question

  • Hello.

    I have a problem with configuring a very specific routing setup. I have a machine running Windows Server 2012 with 2 network adapters. The first adapter has an IP of 10.10.0.2 and a gateway 10.10.0.1 (which is DFL-800 firewall). This adapter is used as a main internet access for the server machine (machine is running various services, including IIS).

    The second adapter is connected directly to a broadband cable modem and receives a DHCP external IP address. What I want to achieve is to make clients from 10.10.0.xxx use this machine (10.10.0.2) as a gateway and the only adapter used for this access should be the second one (DHCP).

    So, in general the first adapter should be used for LAN and internet for the server and the second only for the internet for LAN clients.

    Is this setup possible and how do I do this?


    Tuesday, June 17, 2014 11:00 AM

Answers

  • You can configure a classless route on any computer (using route add), however after thinking about this I don't believe it will be necessary. Just make sure the default route for your server is to 10.10.0.1 and it should use this interface for the Internet.

    You still need the route however for traffic from the 10.10.0.0/24 network so that it sends it out the other interface.

    -Greg

    Wednesday, June 18, 2014 4:37 PM

All replies

  • Hi,

    You provided the IP address scheme for one adapter but not the other, so it is a little difficult to comment.

    You said the second adapter gets a DHCP external IP address. What does 'external' mean in this context?

    Assuming for a moment that the second adapter is 192.168.10.2 and your cable modem is 192.168.10.1, I think you are asking how to make clients on the 10.10.0.x network get out to the Internet via 192.168.10.1 (the cable modem).

    First of all, you would need to install routing on the server, assuming it is the only link between the 10.10.0.x and the 192.168.10.x networks. Then, you would need to configure a route that sends all traffic from 10.10.0.x to 192.168.10.1. If you wish for the server to use 10.10.0.1 itself, then configure this as the default route and also add a classless static route for 10.10.0.2 pointing to 10.10.0.1 so that the other route (to 192.168.10.1) isn't used by the server itself. You might also want to make sure that the 10.10.0.2 interface is preferred on the server over the 192.168.10.2 interface.

    Clients on the 10.10.0.x network will need to have a default route of 10.10.0.2. When the server gets this traffic it will see that it is from 10.10.0.x but doesn't match the classless route of 10.10.0.2, so it will send it to 192.168.0.1.

    This might take a little tweaking. I haven't tested these routes myself for your scenario.

    -Greg

    Tuesday, June 17, 2014 8:25 PM
  • Hello.

    First of all, thanks for the reply. The second interface is receiving a public IP of something like 93.77.150.xxx and some other external gateway IP which is assigned by ISP. I have no control over it and it's not static. Cable modem (192.168.100.1) does not support routing, setting it as a gateway results in no internet.

    Will the above setup work for this scenario?



    Tuesday, June 17, 2014 8:36 PM
  • Hi,

    The formatting in your reply came out a little strange. I think I understand though.

    The public IP address that your server receives will have an associated default route. This is your ISP's router and it is where you will need to send traffic from 10.10.0.x. Everything I said before still applies.

    You must install routing on the server so that it can move packets from one network to another.

    If you don't want the server itself to use the public IP address to get to the Internet, this is a little tricky, but I think it can be done by creating a classless static route as I described. You want to send everything from 10.10.0.x to your ISP's router, except for 10.10.0.2 which you want to send to 10.10.0.1.

    -Greg

    Tuesday, June 17, 2014 8:46 PM
  • Thanks for the followup. I'll try it tomorrow and let you know how it goes.

    Tuesday, June 17, 2014 8:53 PM
  • I just realized that the server machine (10.10.0.2) is not a DHCP server and I can't setup any classless routes on the DHCP server, which is DFL-800 (10.10.0.1).

    Or I'm looking into a wrong direction and those routes can be set somewhere else?


    Wednesday, June 18, 2014 9:26 AM
  • You can configure a classless route on any computer (using route add), however after thinking about this I don't believe it will be necessary. Just make sure the default route for your server is to 10.10.0.1 and it should use this interface for the Internet.

    You still need the route however for traffic from the 10.10.0.0/24 network so that it sends it out the other interface.

    -Greg

    Wednesday, June 18, 2014 4:37 PM