Router behind Router--second router (and its clients) cannot be "seen" even after both routers are DMZ'd/Port forwarded

Question

Couple of terminology I guess I should get out of the way for consistency's sake throughout the post: External Router/Modem - SMC 8014WG - External IP 173.32.144.134 - Internal IP 192.168.0.1

Internal Router - LinkSys WRT120N - "External" IP of 192.168.0.175 - Internal IP 192.168.1.1 - Connected via Ethernet Cable (a really long one, from the basement to the second floor)

PC - IP 192.168.200 - Connected Wirelessly via WAP2 Personal.

Laptop - Used to try and diagnose the problem, a 4th machine to the setup which won't be part of the final setup once everything works.

---

The actual problem:

I've tried setting the LinkySys router as a DMZ'd client on the SMC router, and then DMZ'd the actual PC on the LinkSys. So the DMZ looks like this: On the SMZ, client with IP 192.168.0.175 is DMZ'd. On the LinkSys, client with IP 192.168.1.200 is DMZ'd.

No dice.

I then tried port forwarding the necessary port on the SMC to the LinkSys (lets just say, port 80). Then port forwarded Port 80 on the LinkSys to the PC. Same as the DMZ scenario above, but change DMZ with port forwarding.

No dice, still :(.

Now here's where I went stupid--and tell me if one should never do this--I enabled both DMZ and port forwarding at the same time. I fired up Opera--my browser of choice ;)--typed in 173.32.144.134:6333 and...

... Third time is the charm they say? Well, clearly not. Otherwise I wouldn't be here ;).

To diagnose the problem, I enabled "Allow remote access to the Admin panel" on the LinkSys router, and specified port 6333 as the port to use. I port forwarded port 6333 on the SMC to 192.168.0.175, and access my external IP of 173.32.144.134:6333 in hopes of seeing the Admin panel... No dice (I think I've ran out of dice by now ;)). So to see where the problem was, I connected a laptop to the SMC via LAN cable, and typed in 192.168.0.175:6333, and viola, Admin Panel access!

So the problem looks like it lies with the SMC--But that's as far as I've got, I've done the port forwarding, the DMZ'ing, and I've even disabled the built-in firewall for safe measures, but nothing worked.

So, here I am. Unable to connect to the PC behind the Internal router externally, and without anything to go on other than to come here and ask for the wisdom of the the superuser folks :).

If any more detail is required, just ask.

(Apologies in advance, if questions should never be this long winded!)

Answer 1

I'd ignore the whole DMZ thing, it probably doesn't do what you want it to do anyway.

Just concentrate on port forwarding. Start by forwarding some port on the SMC to some computer behind the SMC. From an external ip, can you get to that computer? If yes, then set the SMC to port forward to the Linksys.

Configure the Linksys to port forward to your box, and if all goes well, you should be set.

Some notes; Your linksys router may not be configured to allow access to the administrative panel from the external network, so it is not a good test. While you were able to connect to it from the SMC Lan, it may be because of the DMZ, which you should disable. You should also make sure that the test computer you are port forwarding to has all firewalls completely and fully disabled.

Good luck ;)

Answer 2

@ Trioke

I've read more than three times, but if I understand correctly you have not mentioned what you actually wanna do or what's the actual problem you are having BESIDES that you can not see admin panel of external router/modem SMC 8014WG from your laptop(while it's connected via Linksys)...

So I'm gonna just guess that you want some port forwarded to your laptop ultimately. If that's the case, you could try disabling DHCP server in your Linksys WRT120N and let the SMC-8014WG assign the IPs to your internal network.

Instruction on how to disable DHCP server in WRT120N are on page 7 (index page#7; pdf page#11), chapter-3 of this User Guide at linksysbycisco.com

And if you decide to give it a shot, reboot your laptop after you disable DHCP server on Linksys, so the laptop will get a new IP from SMC router.

EDIT#1:: Another way would be, to disable NAT, firewall & DHCP server on SMC-8014WG and let Linksys-WRT120N assign IPs(DHCP server enabled), manage NAT & firewall. SMC-8014WG User Manual.

EDIT#2:: Earlier I didn't even notice that it was asked on June 09, 2010 ?? Somehow I found this on 1st page of Superuser.com