DHCP kills connection

[Dimitris Kogias]

> Yeah now it works with dhcpcd. Thanks a lot Roy!
> After trying out several ideas I suspected that dhclient, pump and 
> probably most other DHCP clients take down the interface as I noticed 
> when making a WEP connection.
> I really wonder why I havent't found anything about this issue neither 
> in the mailinglist nor in the documentation. I think this should be 
> mentioned somewhere as most 'regular' users use DHCP with their wlan 
> routers and have no idea about the DHCP process.

Disclaimer:  I'm not at all familiar with the internals of the dhclient
binary itselt.

I've been using wpasupplicant and dhcp3-client - both from Debian
unstable - on a WPA-PSK wlan for 2+ months.  I've never seen this problem.

As far as I can tell, the /etc/dhcp3/dhclient-script explicitly brings
the interface up during the PREINIT stage:

    PREINIT)
        # The DHCP client is requesting that an interface be
        # configured as required in order to send packets prior to
        # receiving an actual address. - dhclient-script(8)

        if [ -n "$alias_ip_address" ]; then
            # Bring down alias interface. Its routes will disappear too.
            ifconfig $interface:0- inet 0
        fi
        ifconfig $interface 0 up

        # We need to give the kernel some time to get the interface up.
        sleep 1
        ;;

Occasionally the first DHCP request will time out, which I take to mean
that the 1+ second delay is not enough for wpasupplicant and my AP to
complete the authentication.

FWIW the DHCP server is not the AP itself but a box on its wired side,
running dhcp3-server also from Debian unstable.

In general this setup has been very robust, including through swsusp.

D.