Time based firewall rules & force DNS to specific subnet

Hi..

I have

eth0 192.168.1.0/27

eth1 pppoe

eth2 192.168.2.0/27

eth3 192.168.3.0/24 (DHCP enable)

I want to make 192.168.3.0/24 internet connection available on 6 AM to 14PM only.

And I want to force every client on 192.168.3.0/24 using Open DNS.

Help me please.

Thank you.