How to set automatic time in our private WIFI network on MarshMallow
Requirements

1.Root access

2.Busybox : for 'rdate' service

3.init.d folder in /system/etc/ to start daemon service at boot

mount system partition in read write :

su -
mount -o remount,rw /system


Create a file 99my_daemon at /system/etc/init.d with executable permission and enter the following lines

#!/system/bin/sh
while ! ping -c1 "0.pool.ntp.org" &amp;&gt;/dev/null
do wait 10
done
/system/xbin/busybox rdate -s 0.pool.ntp.org
exit 0


Close writing the /system partition

mount -o remount,rw /system


And reboot, your system should be connected to the 0.pool.ntp.org and synchronized when he booted. You could use the crontab to check synchronization during the using of the device