DHCP and ancontrol!

[Luigi Iannone]

Hi,
I have an Compaq laptop (2100ca model), I've installed FreeBSD 4.9!
I'm starting to play with my Cisco Aironet 350 Series!
I Know that DCHP and an work not so fine at bootstrap since the interface
is not able to get the address. Not a problem I made a script!
But each time that a to a change with ancontrol the interface doesn't work
anymore. Each time I have to kill the dhclient and to restart it!
But the worst think is that if a want to set an0 in this way

ancontrol -i an0 -M 1

to enable monitor of 802.11, the DHCP stops work, even if I kill the
process and restart it.
Is this related to BPF???? Any known bug? Or just me?
Thanks
                         Luigi