root@carl-desktop:~/tmp/madwifi-0.9.3.3# dhclient ath0
There is already a pid file /var/run/dhclient.pid with pid 5878
killed old client process, removed PID file
Internet Systems Consortium DHCP Client V3.0.5
Copyright 2004-2006 Internet Systems Consortium.
All rights reserved.
For info, please visit http://www.isc.org/sw/dhcp/

wifi0: unknown hardware address type 801
wifi0: unknown hardware address type 801
Listening on LPF/ath0/00:1b:2f:c0:91:1f
Sending on   LPF/ath0/00:1b:2f:c0:91:1f
Sending on   Socket/fallback
DHCPDISCOVER on ath0 to 255.255.255.255 port 67 interval 3
DHCPDISCOVER on ath0 to 255.255.255.255 port 67 interval 7
DHCPDISCOVER on ath0 to 255.255.255.255 port 67 interval 14
DHCPDISCOVER on ath0 to 255.255.255.255 port 67 interval 7
No DHCPOFFERS received.
No working leases in persistent database - sleeping.