Okay, I'm kinda confused with networking. Here's what I wanted to do..

I have a (DRBL) Ubuntu server that has 2 NIC.

eth0 - will have access to internet and local network (10.160.1.10/24)
eth1 - will be my private network (192.168.101.254/24)

eth1 is NAT to eth0 so that it will have internet access. I setup a DRBL environment and configured that the (DHCP) IP range between 192.168.101.10-20.24 will be assigned to Linux clients.

What I want to do is.
192.168.101.10-20 = for Linux machines, should have access to internet. (ive already done this)

192.168.101.30-40 = for Windows machines, should not have access to internet but to local network only.

How can I configure this correctly?
Please help me..

Maybe try a /28 instead? This will give 14 addresses per net (close to your 10). Then you can use vde2, openvswitch or another method to create virtual NICs/devices. Use DHCP to assign addresses. You could then use a bridge and/or iptables to provide needed network access or fencing.

Another option is Ethernet aliasing and iptables and/or static routing.

vde2 is a good option as traffic can easily be encrypted through tunneling as well as allowing for disparate networks or non-cloud-attached hosts access over your favorite connector (ssh, rsh, http tunnels and even connections through DNS services).

Hope that helps get you on your way. There are other ways to accomplish your goals, but these are fairly easy to implement and provide some versatility for you too. Happy researching... It's a road paved with frustration, time sinks and ultimately happiness and fulfillment.

~~Tigr~