2 NICs in Windows Server 2K8. Confusion in IP settings please help...

By sean.ipt ·
My main computer has 2 NICs, one to be used for internet and other for local network computers. This IP configuration part is very much confussing (i m a novice in this part).

i want to share internet connection to lan computers from second NIC.

How do i configure ip addresses for both the NICs?

Current Connection:
Internet-->Router-->Main computer-->Switch-->LAN comps.

Please don't say to change the connection mode... thanks in adv.

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All Answers

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You may want to use RRAS.

by seanferd In reply to 2 NICs in Windows Server ...

Use the RRAS snap-in to configure the routing, and configure the adapters accordingly.

I cannot really be more specific, but I'm sure I could figure it out if I had that setup to play with. I'm certain that you, as a network admin, can do it.

If that doesn't help, you'll have to wait for someone else.

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IP for local NIC.

by sean.ipt In reply to 2 NICs in Windows Server ...

Unable to share internet, local NIC status is shown "Unidentified".

When trying to enable ICS, an IP conflict error message window pops up thereby losing internet access.

Someone please tell me what do i do. i don't wanna go for RRAS.

Current settings for Internet NIC:
IP - (Manually assigned)
Subnet mask -

Local NIC:
IP -
Subnet mask -
Default Gateway - left blank
DNS - left blank

Server Roles: DHCP


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You need to decide, how you want it to work

by TobiF In reply to IP for local NIC.

Currently, you have your server connected to two different networks, but for some reason, they are declared as the same network.

If the netmask is, then all different addresses that share the same "prefix" 192.168.0.x expect to find each other directly, without passing through any gateways.

The most important question now is:
Do you want your server to filter all traffic to the internet from the other computers, or not? This also means, that if your server is turned off, then no other computer will be able to reach internet.

If no, then you need to change your setup. Let all computers in your network, including your server, have different addresses in the 192.168.0.x space and use the router as the gateway.

If yes, then the network between the modem and the server should have one address space, and the network with your local computers another. Say:
Modem, Server upper nic, Gateway, netmask

Server lover nic, netmask, no gateway
Other computers 192.168.5.x, netmask, gateway

Oh, of course you need to insert suitable DNS everywhere, too. You can safely enter the dns addresses you get from your ISP, or say GoogleDNS and everywhere, if you don't need any internal name resolution (and therefore set up an internal dns on your server).

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Helpful but still unable to connect to multiple networks

by sean.ipt In reply to You need to decide, how y ...

Thanks TobiF you have always been helpful ever since i joined TR.

Yes, i want my server to filter all internet traffics for my LAN comps. So, i'm opting for this set up.

However, following your setting instructions won't help me fix the problem. LAN NIC is still unidentified and ICS can't be enabled.

My settings:

Internet/Upper NIC -
IP -
netmask -
gateway - (ISP supplied broadband router)
DNS: (ISP supplied)

Local/Lower NIC -
IP -
netmask -
gateway - not assigned

What might be the reason for being in the same network if the settings were fine..., please suggest...

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Routing won't work if separate networks share same address space

by TobiF In reply to Helpful but still unable ...

When an IP host wants to connect to any other ip address, it will first check if the destination address is within the same subnet.

For destinations on the same subnet, the nic will simply send out a broadcast request for the destination to identify itself.

If the destination is located outside the subnet, then all traffic will be directed to the default gateway.

Now, with your current settings, your server won't be able to tell the difference between the both networks. According to the subnet address spaces, the modem should be available through both nic's. And all other computers will also be contacted through the upper nic, since they seem to be on the correct subnet.

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Well, What Next!!

by sean.ipt In reply to Helpful but still unable ...

Then what do i go for if i desparately want this setup. i mean the control of network traffic from server through Windows Server 2k8 platform. Any change is required in router settings?

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by TobiF In reply to Well, What Next!!

I suggested some ip addresses in my first post.

Most important is to use different subnets for both your networks.

When that's corrected, then you can try to set up the ICS.

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plain old file server

by CG IT In reply to 2 NICs in Windows Server ...

why would you want all traffic to go through the server?

Your perimeter router/firewall is the better place to filter traffic.

RRAS is the only way to go to make your server a router. [RRAS = "routing" and remote access]. Then the server becomes a router and can route/filter traffic for all hosts with it's advanced firewall features.

note: you don't actually have to use the remote access features. no one could get in anyway with a perimeter router not setup to pass traffic to the server.

but throughput for lan computers will be whatever the server throughput is.

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by sean.ipt In reply to 2 NICs in Windows Server ...

Thanks TobiF and others for sharing all those helpful info. i'll see some other way... thanks once again.

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