How can I login to external ADSL Modem

[BillyBoy]

I have Wireless router (TP-Link TL-WR1043ND) running dd-wrt on lan ip 192.168.1.1, and external adsl modem (Edimax AR-7211A) on lan ip 192.168.2.1 setup to be bridged, and PPoE adsl username and password configured on wifi router.
Edimax has 1 LAN port and Adsl port. Wifi Router has 4 LAN and 1 WAN port connected to Lan port of modem.

Question: how can I login to external Edimax modem to see adsl stats and sync speeds/attenuation/logs (without having to disconnect Lan cable from Wifi to Modem). I know they are different IP ranges. The Modem has facility for a 2nd Lan IP address and subnet (which I set to 192.168.1.2/255.255.255.0) but I cant login nor ping it from wifi network.

Is there some fancy routing or subnetting I can do to achieve this?

 

[RoganDawes]

I have a similar setup to you, also the TPLink 1043, but I am running OpenWRT on mine.

Earlier versions of OpenWRT had issues with having an IP address on the same network interface that was used for PPPoE bridging, and would deconfigure the IP address whenever the interface went up or down. This made it impossible to get through to the ADSL modem on the other side of that interface. Fortunately, more recent versions of OpenWRT do not have this problem, making it a pretty simple problem to solve.

I mention this because, to the best of my knowledge, DD-WRT is based on an older version of OpenWRT, and likely suffers from the same problem.

Do you have SSH access to the router? It may be possible to update the configuration to add an IP address to the eth0.2 interface, and add suitable routes or IPTables rules to allow you to reach the ADSL modem, even if the underlying OS doesn't really support this.

 

[BillyBoy]

I can enable SSH access to router, but not sure what to do when logged in. I also have spare Linksys WRT54GL routers running DD-WRT with same issue.
I can change either router to OpenWRT but what changes must be made then to allow access to modem?

How do other people access their external modems? Is there a simpler 'I never thought of doing that' kind of way.

 

[RoganDawes]

So, the main things you want to check are whether your upstream (WAN) interface has an IP address or not, and then, if you can organise routing to that network.

In my case, it looks like this:

# ifconfig eth0.2
eth0.2 Link encap:Ethernet HWaddr <snip>
inet addr:192.168.202.3 Bcast:192.168.202.255 Mask:255.255.255.0

So, from the router itself, I can ping/telnet/HTTP to my ADSL modem. If yours does not show an IP address for "inet addr", you won't be able to do it from the router, much less from your PC.

Once basic connectivity is established, you can move on to enabling connectivity from your LAN. This generally requires creating a new zone for the network in the firewall config, then allowing traffic between the zones. Not sure how DD-WRT does it, though.