problems with udhcpd

[Denys Vlasenko]

On Wed, Jan 31, 2018 at 1:08 PM, Matti Sillanpää
<maash.1.bridge at gmail.com> wrote:
> I've got imx7d based picopi with technexion yocto linux. It has busybox
> distribution of udhcp. I'm trying to use it as hotspot, however occasionally
> it just wont give out IP address altough there's no clear error messages
> anywhere. I've observed this phenomenon on two different android phones.
>
> However in non-working case the connection just drops after certain timeout:
>           Jan 31 09:52:58 imx7d-pico CROND[773]: (root) CMDOUT (wlan0: STA
> cc:9f:7a:da:ed:4a RADIUS: starting accounting session AF1A9D2B-00000000)
>           Jan 31 09:52:58 imx7d-pico hostapd: wlan0: STA cc:9f:7a:da:ed:4a
> WPA: pairwise key handshake completed (RSN)
>           Jan 31 09:52:58 imx7d-pico CROND[773]: (root) CMDOUT (wlan0: STA
> cc:9f:7a:da:ed:4a WPA: pairwise key handshake completed (RSN))
>           Jan 31 09:53:34 imx7d-pico CROND[773]: (root) CMDOUT (wlan0: STA
> cc:9f:7a:da:ed:4a IEEE 802.11: disassociated)
>           Jan 31 09:53:34 imx7d-pico hostapd: wlan0: STA cc:9f:7a:da:ed:4a
> IEEE 802.11: disassociated
>           Jan 31 09:53:34 imx7d-pico CROND[773]: (root) CMDOUT (wlan0:
> AP-STA-DISCONNECTED cc:9f:7a:da:ed:4a)
>           Jan 31 09:53:34 imx7d-pico kernel: CFG80211-ERROR)
> wl_notify_connect_status_ap : event WLC_E_DEAUTH_IND(6) status 0 reason 3
>           Jan 31 09:53:34 imx7d-pico kernel: CFG80211-ERROR)
> wl_cfg80211_del_station : Disconnect STA : cc:9f:7a:da:ed:4a scb_val.val 3

The station disassociated from your AP. No dhcp messages at all before that.
tcpdump'ing packets from the station may give useful information.
Were there any dhcp discovery packets from it?

What crond has to do with network?
Why disassoc messages come through crond?

> I'm starting the hotspot along these lines:
>     ifdown wlan0
>     rfkill unblock wlan
>     killall wpa_supplicant
>     killall udhcpc
>     echo 2 > /sys/module/bcmdhd/parameters/op_mode
>     ifup wlan0
>     udhcpd /etc/udhcpd.conf
>     hostapd /etc/hostapd.conf &
>     udhcpd start

Looks like typically awful method of ad-hoc networking.
What "udhcpd start" supposed to mean?