How to set up a gateway?

Question

linux

There is an Internet coming via ADSL after the modem, there is a gateway with 2 network cards, which receives an external ip from the modem and already gives an internal ip (from the network 192.168. how to do if you need to protect 5 computers from a common network so that no one sees them in a networked environment, but leave them access to the Internet (i.e., as I understand it, they need to be thrown into a separate network, but how is this implemented, what queries to search for no representation)
gateway: OS Debian 7
computers: OS windows 7 or XP or server 2008

Answer 1

look for the word VLAN
Here, for example, for debian
But note that your network switches must also support VLAN. Or you will have to hang everything on different interfaces