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IP Forwarding

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by wdjacks

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I have a Proliant 1600 running NT 4.0 Service pack 6. I have installed a second NIC card to do IP forwarding directly from my Cisco 1601R Router - into 2nd NIC and out to my LAN that is connected to primary NIC.

We obviously have an ISP, and allI-Net traffic is by way of the Cisco router. I gave IP forwarding enabled on bot NIC's with the only protocol for both NIC's being TCP/IP.

I am also using a cross-over cable directly from the 10 BASE T port on the back of the router, directly into the second NIC on the server. I get a good 10 BASE T indicator light on both the router and the server NIC- But I cannot get my traffic to pass through the server.

My ISP tells me that they have added a static route to the IP of the 2nd NIC into the router.

My understanding is that this is not supposed to be this difficult. Are there any services/configurations/protocols that I am overlooking?

1000 point to solve this dilemma!

13 replies

by c:\\>

Ask first your ISP to delete the old static route if any. Then make sure that the routing table is correctly set up on your server. I am talking about the routing between the two of network cards. It looks to me that the problems is the routing between the cards. It might be that the second network card (the one towards the router) either does not receive the packets from the other card, either does not know what to do with them. Also make sure that the routing for the card towards your internal network has the routing correctly set up.

by ckaylam

I think there are totally two solution
Download the RRAS from Microsoft , It make NT server to become a router.
*Attention : Enable IP forwarding is equal to dont lock the door at night, allow the crime occur*
I think the better way is setup yourNT server as a Proxy Server so that you can filter particular protocals/block access to certain website (more control and more security)and even Web cache server(more efficiency of the bandwidth if the PC users mostly access the same website.

On the client side, only need to install a proxy client software

About the Proxy server setup. Dont worry, buy a Microsoft Official Internet Information Server Training Kit provide enought information of proxy server

by computerdude

Do you have the default gateway of the internal NIC set to the IP address of the external NIC? And then the defult gateway of any computers on the LAN set to the address of the internal NIC of the Proliant? If that is done you should have no problempassing traffic. You do know that with this senario and no firewall your network is wide open right?

Hope this helps,
Dave

by c:\\>

What type of router you have ? It might not need a crossover cable. Some of the routers are including a couple of connection ports.

Can the network cards ping each other ?
Can you ping the router from both cards ?
What type of router you have ?
What type of Internet connection you have ?
Are you sure that the router ports are open ?

by rsoft

First of all, are you certain nothing goes through the server? Or is it just that the www-server you are trying to access doesn't know who to reply to.

What is the IP-range inside your LAN?
Is it Internet routable (in other words: did you register an IP range with InterNic..)?
Do you use IP-masquerading?

Most people think that One-way traffic suffices (I did too), but if a packet reaches a server and the server doesn't know of any route back (back-tracking is not implemented) it seems like the server is unreachable.

Please feel free to email.

by wdjacks

The problem is definetly in my routing table. I know this because when I run the router directly into the second NIC car on the server, as opposed to the network switch. Online works fine for that server. So that part of the theory is working. The part I can't conquer is how to get my network to find the internet router (ISP) through that server as opposed to the LAN.

I'll be home free if I can set the routing table up properly.

I use the 10. network for my LAN. The router to my ISP is also 10. My ISP does all the translation. I even tried obtaing a routable IP address, but that didn't work either.

The problem is routing my LAN to that servers "external" NIC.

by rsoft

Ok, let's try it the other way.

Could you please do a: "route print" on the server and send me the result?

In that mail could you please send me the IP's of the following things:

router (internal side)
Server NIC (router side)
Server NIC (LAN side)
LAN (network number and netmask)

Next could you try the following things (in this order):

ping router from server
ping NIC on router side from LAN
ping router from LAN

Please send me the results at technicalqa1@rsoft.demon.nl

by wdjacks

Through all of your efforts I was reminded that you cannot route in a single network environment. I first learned this with my WAN traffic - I wanted to use all 10.81.1.0 (which I did), and my WAN 3rd party informed me that "I won't be able to route then - I'll have to bridge".

I simply neglected to apply this WAN principle to my LAN.

Changing the external NIC of the server, to a different network, but the same as the, server side, router IP will allow me to "route" to the second network via the server's internal NIC, and back to the primary network as well.

I may not have spoken it clearly, but I understand the concept, and look forward to verifying the theory.

Thank you.

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