Tomato Wireless Bridge + forgetfulness = ???
November 22, 2009 10:15 AM   Subscribe

Tomato Wireless Bridge + forgetfulness = ???

I have a linksys wrt54gl router with tomato firmware configured as a wireless bridge. This makes the router 'invisible' on the network. My problem - I have no recollection of the device ip address. It is still functioning correctly but I want to reconfigure.
In theory I should be able to connect via ethernet port and go to admin webpage but without knowing the ip - or even the subnet - I am stuck!
If anyone has a solution then I'm all ears.
posted by xla76 to Computers & Internet (6 answers total) 1 user marked this as a favorite
You might try this:

And then it should reset to defaul settings (presumably / admin). you'd have to reset up as a wireless bridge, but that doesnt seem too hard sounding from what i read about tomato.
posted by CharlesV42 at 10:26 AM on November 22, 2009

If you don't mind some elbow grease, just guess at the IP address. If you've got the usual 192.168.1.* home network there's only 255 to try. Or if you want to be clever, run WireShark in promiscuous mode from your PC and see what other local machines are on your network. The only problem there is the bridged traffic won't show up under the bridge's IP address, so you'll have to look for some infrequent other traffic. NTP requests? ARP?
posted by Nelson at 10:31 AM on November 22, 2009

What are you bridged to? Can you get the IP address from that? Other suggestion is to look at ARP traffic.
posted by kellyblah at 11:25 AM on November 22, 2009

Below the IP level, your machine maps IP addresses to Ethernet MAC addresses. Then, it dumps an Ethernet frame, properly addressed, onto the wire, and all the machines around listen for frames addressed to them.

That IP-to-MAC mapping is possible because there's an address resolution protocol ("ARP") built in to Ethernet. A weird frame is set out to all hosts, which asks, "who is address w.x.y.z?" When someone knows, they send back a weird frame "w.x.y.z is MAC a:b:c:d:e:f:g:h".

What you should do is ask your computer to display its ARP table. On my Linux machine, this is by typing "arp -a" in a terminal. That shows pairs it already knows about.

You should then get your machine to look up all the addresses in the range where the bridge might be.

There's a problem, though. If your machine has an address that is not on the same block of addresses as the bridge, then even if you scan the bridge range, you'd never see the host. When you try to reach an address in the "local" block, your machine will send its request to the upstream "router" instead probing the local network.

Whatever the address of the bridge, your local host *must* be set to think that the bridge is on the same network, if you want to talk to the bridge.
posted by cmiller at 11:28 AM on November 22, 2009

just nmap -sP or and go eat a cookie
posted by zentrification at 2:28 PM on November 22, 2009

ARP was the answer! Thanks all, especially cmiller for the detail. Command for windows is the same 'ARP -a'.
posted by xla76 at 3:38 AM on November 23, 2009

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