Hy guys i have a big problem, i have for example 10 computers and i want to split them in two, and i have a linus router.My eth0 is the internet adapter and my eth1 is my private network adapter, and i want to split my eth1 in two virtual network adapter. The first ip for my first 5 comp and my second ip for the others 5. And i don't know how to split in two network adapter(eth1). And i know it's possible.

Thanks in advance.

You will need to have each set of 5 computers on a separate subnet, and assign two IP addresses to eth1 on the router. One IP address which belongs to the first subnet, and the second IP which belongs to the second. The routes would be setup with entries for each subnets but the device would be the same (eth1). I am assuming that you want to have 5 computers exposed to the internet, while 5 computers are isolated.

You may be able to accomplish the same thing without subnets, by setting up the firewall properly, but the iptables would be less general and the firewall may be less efficient.

Keep in mind, that because the 2 groups are physically connected to the same hub or switch, then there is a danger, because if one of the exposed hosts is compromised, the other hosts are at risk. What you are trying to do is similar to putting a host on a cable/router in the DMZ in the setup, but you have 5 computers in the DMZ and not just one.

Here is a link which does a much better job of explaining my point.
http://www.grc.com/nat/nat.htm

Thanks for the hint, And were is the link.

Anyway wanted to split my eth1 in two diffrent ip's like

|This is my primary eth1

eth1:1(192.168.1.1)
/
eth1
\
eth1:2(192.168.2.1)

I want to do something like that and i know it's possible and i want to know how i do that.
The rest of the firewall i can handle with.

Thanks for trying to help me.

Sorry, I edited my previous post to include the link.

I have a problem on my laptop where I'll bump a random item on the touchpad and go back on the browser or what not. Then when I recover, I'll post my pre-edited page without realizing.

assuming eth1 is already assigned 192.168.1.1

ifconfig eth1 add 192.168.2.1 netmask 255.255.255.0

will multihome eth1 so it will respond to both addresses

eth1 192.168.1.1
eth1:0 192.168.2.1

Thanks a lot you helped me.

I'm trying to do something similar, but I want multihome eth0 when it is part of a bridge. Both eth0 and eth0:1 work fine when I multihome eth0 without bridging. As soon as I add eth0 to the bridge eth0:1 stops working.

well if u want to work on youre internet interface u will have to change some ruls in the firewall of youre system. Try that and give me an answer.