Port forwarding/Pinholing. OR Behind two NATs?? (Prob similar setup to many people)

Dave Roe

I have a Netopia 3341 modem and a Linksys WRT54G router.

I've spent a long time trying to get connected by fiddling with the router, changing ports and forwarding all to no avail, until finally yesterday I unplugged it altogther, and used the modem only. That didnt get me connected but, on the modem I added what it calls a pinhole (and which, I beliueve is just another name for port forwarding) and became connected - Oh Joy!

But, when I now connect back up my router I'm back to square one.

So, here's my question - can my modem be NATing even if its not really a router itself? Seems to make sense if I had to 'pinhole' the port I chose to allow it to connect on the PC

Secondly, if that's the case - what do I need to do to be able to use the router and still port forward from it to the PC where I use the bottorrent client?

Portforward.com has a handy section on portfowarding on two routers and that leads me to my final question -

It says "Notice that the ip addresses that exist on LAN1 differ from the ip addresses on LAN2. The ip addresses that are on LAN1 are 192.168.1.1 and 192.168.1.5. The ip addresses that are on LAN2 are 10.0.0.1 and 10.0.0.15."

I am not set up like this - when I take the router out of the equation ...
the modem itself is at 192.168.1.254 and
My PC (static IP) is at 192.168.1.100
The remote G/W is at 159.134.155.27
It says the WAN local address is 213.94.241.213
and the peer address is 159.134.155.27 (*which is what my external IP looks like)

I pinhole/forward port XXXX to my PC at 192.168.1.100 and all is well.

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Now, I recconnect my Router between the Modem and the PC -

My PC is still at 192.168.1.100
The router is at 192.168.1.1 - and yet also seems to be at 192.168.1.6 ???
The "default gateway" is at 192.168.254

I have the same Port XXXX set to forward to the PC at 192.168.1.100, but no joy.

click to see full size

Thanks for reading this far - should I change the IP address of the LAN connected to the router - presumably by changing the routers own IP address and the static IP address of the PC (and other devices on that network) so as to make it different from the addresses on the LAN between Modem and router?


From Portforward.com - "We want to forward ports from the WAN of R1 to a computer connected to LAN2. To do this we need to forward the ports in R1 to R2's external ip address. In this example we would log into R1 and forward ports to 192.168.1.5. It is important to note, that to connect to R1's web interface we will probably have to plug a computer directly into R1. The next step is to forward ports from R2 to the computer you plan on running the program on. In our example we would log into R2, and then forward ports to 10.0.0.15"

It seems that if this is my setup - I need to change the whole LAN IP addresses as it describes above.

OR

Do I just need to st this pinhole(On the modem) to forward to 192.168.1.1 (i.e. the router) and let it then port forward to 192.168.1.100 (ie. the PC) ???


Have I needlessly confused myself at this stage?


Thanks for any help you can provide.

Malafus

The Netopia 3341 IS a router, as well as a modem. You are needlessly complicating the situation by trying to connect through two routers.

All you must do is use JUST the Netopia, and pinhole through that. Connecting the modem to a switch will solve the problem.


If you must use two routers, then you have many problems ahead of you:
The Netopia lies on it's own IP domain. As you know, it defaults to the address of 192.168.1.254. Your Linksys' external IP must lie in the same domain, but at a different address, say 192.168.1.50. The Linksys' gateway must be set to 192.168.1.254.
Your interal network should lie on another domain entirely, say 192.168.2.*.
Set the Linksys' internal IP to, how about, 192.168.2.250, and then set all your connected devices to have that address as their gateway.

Step 2) Connect to the Netopia, and have it forward whatever ports you require to the Linksys (192.168.1.50). Connect to the Linksys and have it forward whatever ports to wherever they need to go (192.168.2.*). This SHOULD solve the problems.

Dave Roe

Malafus wrote:

The Netopia 3341 IS a router, as well as a modem. You are needlessly complicating the situation by trying to connect through two routers.

All you must do is use JUST the Netopia, and pinhole through that. Connecting the modem to a switch will solve the problem.


If you must use two routers, then you have many problems ahead of you:
The Netopia lies on it's own IP domain. As you know, it defaults to the address of 192.168.1.254. Your Linksys' external IP must lie in the same domain, but at a different address, say 192.168.1.50. The Linksys' gateway must be set to 192.168.1.254.
Your interal network should lie on another domain entirely, say 192.168.2.*.
Set the Linksys' internal IP to, how about, 192.168.2.250, and then set all your connected devices to have that address as their gateway.

Step 2) Connect to the Netopia, and have it forward whatever ports you require to the Linksys (192.168.1.50). Connect to the Linksys and have it forward whatever ports to wherever they need to go (192.168.2.*). This SHOULD solve the problems.

Thank you for the informative response, which unfortuantely confirms my fears.
I have to use the router, since I have some wireless devices which rely on it too.
I think I can do this - I can set the IP domain of the Linksys, the largest problem is though, that once I am connected to the router I can no longer see the Netopia. I have heard there is a way to do this - possibly by also port forwarding the control of the Netopia? Is that correct?

Thanks again!

Malafus

I figured as much... you cannot "forward" the Netopia config menu, as such, as it's not an incoming packet that is being blocked (It's a simple HTTP interface, on port 80). The problem is that you connect to it by entering 192.168.1.254 when on its own network... you need to use an IP passthrough, or something like that.

There are two options here:

1) Set up remote access. This feature, embedded within the Netopia modem (at least on the newer firmware) allows you to connect to the modem from anywhere, by connecting to a specific IP addy (with a password, which you specify). It's horribly inelegant, as you'll be going PC->Linksys->Netopia->Web->Netopia, but it would get the job done.

2) IP passthrough... this allows a PC to have the same IP address as the external port on the router - If you were to set this up, it would be on the Linksys and you would need to have it forward to a PC on the internal network. The problem here is that the computer you have selected to be the passthrough receiver will be the only one able to connect to the Netopia, and it might cause other problems with the other connected devices. (If you wanted to forward anything to it from the web, you'd have to specify the address you picked previously for the Linksys external - 192.168.1.50 was my example)

There are pros and cons to each decision, but personally I would try #2. If it caused any errors at all, I would switch to #1. If you want to be able to access the config menu from all the connected PCs, then #1 is your only choice, as far as I can see.

Good luck.

Giblet

I have a similar setup, but I have my DSL modem in bridge mode, so it's just the wireless router doing everything.

Malafus

Giblet wrote:

I have a similar setup, but I have my DSL modem in bridge mode, so it's just the wireless router doing everything.

Yes, just now I found the bridge mode for the Netopia router... which makes the whole process a hell of a lot more straightforward. I wasn't aware of it's existence(though I suspected) because I've never had any need for it before.

OP, you just need to connect to your Netopia modem, go into Expert Mode->Configure->Connection
There's an option called "Bridging". Set it to enabled, and then have your Linksys router do all the work.

Dave Roe

Malafus wrote:

Yes, just now I found the bridge mode for the Netopia router... which makes the whole process a hell of a lot more straightforward. I wasn't aware of it's existence(though I suspected) because I've never had any need for it before.

OP, you just need to connect to your Netopia modem, go into Expert Mode->Configure->Connection
There's an option called "Bridging". Set it to enabled, and then have your Linksys router do all the work.

Well that sounds Fantastic, and just what I need. (Of course, I am going to try to create the second, inner LAN with the router on a different IP anyway, and end up tearing my hair out at 4am, but now I have a more elegant solution to fall back on when all that goes to pot.)

Thanks for all the info, very informative and helpful.

Dave

Dave Roe

Malafus wrote:

Yes, just now I found the bridge mode for the Netopia router... which makes the whole process a hell of a lot more straightforward. I wasn't aware of it's existence(though I suspected) because I've never had any need for it before.

OP, you just need to connect to your Netopia modem, go into Expert Mode->Configure->Connection
There's an option called "Bridging". Set it to enabled, and then have your Linksys router do all the work.

Bugger - I don't exactly see that, but what I do see seems to imply I already have this set to on



Is that possible - or am I looking in the wrong place?

Malafus

Ah, the "classic" interface. There has been an update to Netopia modems, with a shiny new look to their config menus.

Tick "Enable bridging on Port".