	# find the process invoke path who invoke dhcp-client stop
	pid=`ps ww | grep -e "restart dhcp-client" -e "stop dhcp-client" | grep -v "grep" | head -n 1 | awk '{print $1}'`
	while [ $pid -gt 0 ]; do
		cmdline="`cat /proc/$pid/cmdline`"
		/usr/bin/logger -t dhcp-client -p err "parent pid = [$pid], cmdline = [$cmdline]" || true
		pid=`cat /proc/$pid/status | grep PPid | awk '{print $2}'`
	done

	# stop record packet
	tcpdump_pid=`ps ww | grep "/usr/sbin/tcpdump -i $IFACE port 67 or port 68" | grep -v "grep" | head -n 1 | awk '{print $1}'`

	if ! [ -z $tcpdump_pid ]; then
		kill $tcpdump_pid || true
	fi

