Routing problem (Internet Sharing)

[Guest_imported]

Hi, I have this configuration and I can't connect my clients to the internet, can you help?

DSL MODEM
---------
Internet Router:
ext IP:66.XXX.XXX.XXX
mask 255.255.255.255
Internal IP: 10.1.1.1
------------------------------
Windows 2000 Server
Nic 1: Connected to the router (directly)
IP: 10.1.1.100 mask 255.255.255.0
Nic 2: Connected to a hub IP: 10.1.2.1 mask 255.255.255.0
Clients with IP attributed by the DHCP server
DSN forwarded to the DNS server of my ISP.
NAT enabled to the NIC 1.
---------------------------------
The clients have 10.1.2.* Ip attibuted
(10.1.2.1 IP excluded)

I really don't know what to do more, if you can help, plz do it .

Thanks Guys.

 

[Guest_imported]

I forgot to say that the default Gateway for the NIC 1 is the Ip of the router: 10.1.1.1 and the DNS servers IP are the one of my ISP.

For the NIC 2 the default gateway is the NIC 1 : 10.1.1.100 the DNS server IP is the NIC 1 : 10.1.1.100

 

[Guest_imported]

And if you need more infos: Clients can ping the NIC associate with their network, but can't ping the other NIC attached to the server that is connected to the router.
And clients can't ping the router.

Thank for your help!

 

[mschmid]

Without actually seeing what you have going on, my best guess is that your sever is not passing on the DNS info to your clients. If the router that you are using is able to perform DHCP/nat allow it to do this function. Also, I noticed that on your config you don't show internet router information. Is your DSL modem even seeing the out side?
Good luck.

 

[cvoce]

What Default Gateway is the DHCP giving out to the Client PCs?

Basically, a PC can only see other machines on its own Subnet, unless it has a default gateway. The idea is that, if it cannot directly talk to a machine (ie it is in the same subnet), then it passes the packet to the default gateway. This default gateway does the same thing, and so on all the way to the final destination.

So in your circumstance, the following should be true:

Client machine:
IP=10.1.2.x (x=2-254), Subnet 255.255.255.0, Default GW 10.1.2.1

Server machine NIC on the Internal Network:
IP=10.1.2.1, Subnet 255.255.255.0. No Default Gateway

Server machine NIC on the PUBLIC Network:
IP=10.1.1.100 Subnet 255.255.255.0 Default GW 10.1.1.1

The packet, once it reaches the destination, has to be able to find its way back to the sender. This happens in the same way. Therefore, the DSL Router will need to have a route BACK to the 10.1.2.x network. This isn't usually done with the Default Gateway, as by default you want it to go out to the Internet. Instead you need to set a STATIC route on the Router, along the lines of:

route add 10.1.2.0 mask 255.255.255.0 gw 10.1.1.100 (this is the Windows command... the router will likely have a routing table somewhere that you can put the same info in).

This may not be necessary if your "server" is doing NAT (Network Address Translation). This is when the Internet connection is only really supposed to be used by a single user, and you want to pretend that all internet requests are coming from a single machine (or proxy). Your Router must be doing NAT anyway, because 10.x.y.z addresses aren't routed on the Internet (they are kept for internal networks), so all requests beyond the Router must look like they come FROM the router, not through it. Of course, if the packets come from the Server, they are on the same Subnet as the Router, so the Router doesn't need a route set.

Sorry if I am teaching your granny to suck eggs, etc... it's hard to know where to start sometimes.

Hope this helps,

Chris