I recently upgraded one of my OpenWRT boxes to Kamikaze 7.09 and since then WPA with PSK2 have been functioning quite badly with my IBM x60s running the iwlwifi-1.2.23.

Establishing the WPA connection and fetching an IP address via DHCP works fine but when pinging the client from the OpenWRT box I end up with the following TCP trace:

14:09:56.380229 arp who-has client.wifi.example.com tell 192.168.20.1
14:09:57.380247 arp who-has client.wifi.example.com tell 192.168.20.1

Initially it seems to be related to the second comment on https://dev.openwrt.org/ticket/1569. Where OpenWRT fails to see ARP responses on the wifi interface.

However if I start tcpdump -p -i wlan0 arp on the client I suddenly get an ARP reply and ping works again.

So it now seems more like http://www.intellinuxwireless.org/bugzilla/show_bug.cgi?id=1446

Also the following code from the bug ensures network connectivity:

#include <stdio.h>
#include <unistd.h>
#include <sys/socket.h>
#include <linux/if_ether.h>

int
main(int argc, char **argv)
{
int sock_fd;

sock_fd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
while(1) {
sleep(600);
}
return(0);
}

So this seems to be a problem in the mac80211 subsystem.

I'm running an unsupported hardened GCC 4.1.2 so I haven't really filed a bug.. and the workaround well works :)