Linux ROUTER

I am connecting to the net via adsl modem that is acting as a bridge for my linux box that use rp-ppoe to connect to the internet.
My net:
eth0 connect to a switch.
eth1 connect to adsl modem.
ppp0 the adsl link.

Now my question is:
My ISP has assigned me 8 IP public addresses.

In may local network I have connected to the switch 3 linux box, that I want to assign them a public address and to have them access to the net not with MASQ because they have public IP.
I want that my linux box that is connected to the net via adsl modem to act as a router and to route the traffic between the 3 linux box and the world. I want that any one can access the 3 linux box from the out world without MASQ or NAT.
How I can made my linux box a router.
The actual ppp0 have static ip too of course.
What IP I have to assign to my eth0 and eth1, public or static... how This can be done, please help me.