Lets say i have a cnet, and i have several machines in my network and i want each of them to have their own official ip adress on the net. How can i do that? Do i have to share the internett and ip's in someway ?

There are three different ways you can do this.

If you're connected via a cable or dsl modem with an ethernet port, and your ISP will provide you more than one IP through that modem you could connect all directly to the modem via a switch or hub, and use dhcp to give them all their own ip's. This does open all of the systems up to being directly attacked via their internet connection, but that's a risk you may be willing to take. (I'm not, so I don't, even though I could.)

Next up is simple NAT. To do this, one box on your network has to act as a router. You want to set up your own internal network with a private IP network range, (see my notes in a response in the "IP address which class" thread) The box you set up as the router is gateway for the other computers. Depending upon the version running on this box you will use ipmasq, ipchains or iptables to set up masqurading or network address translation. Good documentation on that can be found at www.linux.org under the documentation button then "how to" link.

Last up but most secure, is to set up proxies for those services that you want to handle. The restriction here is that those services have to have a proxy available. At this point you do not want either IP-forwarding, or nat/masqurading running on the gateway, you only want the proxies and servers you need running. (mail might be a good example of something you want running here.