wpa_supplicant fans like myself may have found the Dapper upgrade a little more jarring than they expected.

Though it’s not mentioned in Dapper’s release notes, the upgrade includes significant changes to wpa_suppulicant’s configuration model, causing an exiting configuration to be disabled without warning.

If you’re using the newfangled Network Manager for a roaming setup it’s very easy to reconnect to your base station. But for stationary servers like my own, you need to rewrite your wpa_supplicant configuration in the new style.

Don’t try to resuscitate your renamed configuration files (as I did at first). Just transfer everything into /etc/network/interfaces and delete the old files. This is my new WPA configuration for talking to an Airport Express:

iface ath0 inet static
        pre-up sleep 10
        wpa-driver madwifi
        wpa-ssid 11
        wpa-scan-ssid 1
        wpa-eapol-version 2
        wpa-key-mgmt WPA-PSK
        wpa-psk H3XC0D3C1TYH3R3
        hostname mini
        address 192.168.3.1
        netmask 255.255.255.0

Good luck with your own upgrade!

UPDATE: Though my setup was working perfectly on a manual ifup ath0, it wasn’t initializng on boot until I added the “pre-up sleep 10” line.