Disabling NAT in DSL modem

[herbalist]

I need to disable the NAT on a Netopia 3341 DSL modem. I have Smoothwall installed on another PC and everything behind it works fine. I'd like Smoothwall to use my actual IP and handle the NAT duties, which is what they recommend. I've tried to follow the instructions on the vendors page but the settings won't validate.

On the WAN interface, I unchecked address mapping per the instructions. Left the rest of it alone.

On the LAN interface, I entered my IP address. Left the subnet as is, 255.255.255.0.

The settings won't validate, says IPs are on the same subnet. With NAT disabled, shouldn't it be the same? I don't understand what this wants. My understanding of this is very limited. AFAIK, I have one static IP address, which I tried to enter on both the LAN and WAN interface.

Can someone help me figure this out?

Rick

[nitroshift]

You can NOT have the same IP address set in WAN and LAN sections of the router. They *must* be different.

[herbalist]

The IP supplied by my ISP is entered on the WAN interface.

The vendor support page reads:

Enter the IP address you will be using as the router's LAN, or ethernet, address. This will be one of the public IP's being routed to you by the ISP.

If I have xxx.xxx.xxx.217 entered for WAN, what's the appropriate entry for LAN with NAT disabled?

Rick

[cluberti]

You can NOT have the same IP address set in WAN and LAN sections of the router. They *must* be different.

Well, that is not entirely true. I doubt the netopia network device can do it, but you can (and the smoothwall could likely be modded to do it) have the same IP address on a LAN and WAN interface - it's called proxy arp.

@Herbalist - you might want to contact the ISP to see what they suggest - I am not sure how the netopia works with regard to LAN and WAN links, and since I do not believe it supports proxy arp, you'll likely need more than one public IP address from your ISP to do what you want to do.

[Stoic Joker]

If the Smoothwall box is going to be handling NAT, then one public IP (for it) should be fine (and cheaper) ... why not looking into configuring the Netopia box as a bridge?

[herbalist]

Bridge!!

That's what I needed. I was sure I was overlooking something simple but couldn't think of what it was. This is my first time working with a DSL modem and the first time I've done anything with networking, if you can call one firewall and one PC a network.

Thank you!

Rick