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Lately, I have been having problems with my router. I have a Netgear N300 v2, but I am not asking for support with said router. No, what I'm actually asking is how someone goes about forwarding their network traffic from the Internet to a server and then have it properly re-routed.

I have never done this sorta thing before, but I want to go into a career in I.T. when I'm older. As a side note, I have already figured out that ditching the router requires to have a software DHCP server, which I am using Windows Server 2008 Datacenter and it's built in role as DHCP server.

DNS is also configured. The modem a Motorola SurfBoard is connected directly to a Cisco Catalyst 2950, and that connects all of the rest of the network, also via a 3Com SUperStack Hub, and a little 8-port HP AdvanceStack J2610A, which connects to all of my wireless APs.

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If your SurfBoard has more then a single port you can simply use it to forward the ports. –  Ramhound Jul 10 '13 at 16:07

3 Answers 3

Your question is a little unclear, but if you're asking how to port forward without a router, the answer is you can't. There needs to be something on the network to do the layer 3 routing (whether it's a hardware router, a layer 3 switch, or a server configured to route for you).

What has the public IP on your network right now?

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Well, this might be incredibly stupid, but I was trying to configure the modem to connect directly to a hub... I have a really fast internet connection, and I'm trying to host services like HTTP and SSH. So now I'm curious how to configure a server to route for me... I have Windows Server 2008 Datacenter, and a bunch of Ubuntu servers, so whatever I need to do I'll do it :) Thanks again in advance –  Tim Powell Jul 10 '13 at 15:00
    
See my answer, Tim: The hub is a "stupid" device in that it doesn't know anything about how to distribute an internet connection to many clients. That's where you need a router. –  Isaac Dontje Lindell Jul 10 '13 at 15:01

To start with, you're going to need something that does the routing functionality. I'm not terribly familiar with the Windows Server world, but I imagine it has some sort of way of doing it.

EDIT: this article may point you in the right direction: http://technet.microsoft.com/en-us/library/cc770798(v=ws.10).aspx

Basically, the modem can assign one external IP address, provided by your ISP, to one device. If you just have one device on your network, then no worries: that one device will have one external IP address and can talk to any other external IP address on the Internet. However, if you have multiple devices all needing internet connectivity through that modem, you then need a router (whether it be a dedicated hardware device or provided by software on your Windows server) to "route" that connection to your internal network.

The router would be responsible for giving an internal IP address (something like 192.168.x.x or 10.x.x.x) to each device on your internal LAN. It's also responsible for passing Internet traffic between the devices on your network (which don't know anything about the external/ISP IP address) and the servers on the wider Internet (which don't know anything about the internal IP address your devices have).

This router, whether hardware or software, would also be responsible for port forwarding if you are trying to run an Internet-accessible server on your internal network.

[Port forwarding basically sets up rules on the router that say, "If a request comes in to the external/ISP-assigned IP address on a certain port, send that request to xxx.xxx.xxx.xxx, where xxx.xxx.xxx.xxx is an internal IP address.]

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You have your cable modem connected to a switch. This won't work.

Cable modems generally will only talk to the first MAC that appears on their single Ethernet or USB port. Other MACs will be ignored unless you reboot the device. On my modem (an Arris, not a Surfboard), if you disconnect whatever is connected to the Ethernet port, it won't talk to anything else if you connect it, except the original device when you reconnect it, unless you reboot it.

If you do not connect a router to a cable modem, the only other valid thing to connect to it is a single machine you want to have internet access. In this situation, you do not need to worry about port forwarding, but definitely need a good firewall configuration on this single system.

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