title: Use iptables to set online time 1 hour per day
body: <p>is there any chance to configure iptables in a way that it allow a machine to be online for lets say one hour per day ? The time module can do this only in a way like "from ... until ..." but I need a more flexible solution. 
  The machine could be online 30 minutes in the morning and then again 30 minutes in the evening but I dont find any way. Do I realy have to write a script for that?</p>