Internal AirPort card and AirPort base station not working

[Jeremy Radlow <jtr@sourcerers.com>]

Has anyone gotten this combination working?  Here's my setup, and a
description of my problems:

* Router
   - IP address 192.168.1.1
* AirPort base station
   - IP address 192.168.1.100
   - transparent bridging, no encryption, gateway == router
* Laptop
   - Internal AirPort card
   - IP address 192.168.1.12, gateway == router
* 2.4.6 benh kernel, airport/orinoco/hermes modules

To get things "working" I use:

# modprobe airport
# ifup eth1
# iwconfig eth1 mode managed

So at this point it should be like my laptop is on the local area network,
right?  And if I ping other machines on the network and check their ARP
caches, the laptop does show up.

I see activity lights on the base station when I try to ping other machines,
but I get 100% packet loss.

iwconfig eth1 shows link quality 57/92, signal level -41 dBm, noise
level -98 dBm.  The base station is five feet away.

tcpdump on the target machine shows dozens of arp who-has and arp is-at
messages generated by the laptop and the target machine respectively, and
nothing else.  The laptop's ARP cache shows <incomplete> for the ethernet
hardware address of the machine(s) I'm trying to ping.

What am I doing wrong?

-Jeremy