private net on a rack

hello
I have a rack with 4 machines in it, and each machine has only one NIC. I want to set up a private local net between them so that when we transfer data from machine to machine it's not done over the entire internet. The OS is red hat 9, 2.4 kernel. is this even possible?

Can't you just buy a switch and connect a cable from each NIC in the computers into the switch?

ok lets clear this up you have four machines in a rack each with 1 NIC im assuming they all have public addresses on the same subnet with internet access? first off if you have 4 machines on the same subnet they use MAC addresses to talk to each other and their traffic from one to the other will not go past the HUB/SWITCH they are on. if on a switch then sniffing is almost impossible ( unless using ARP poisoning ) unless you have access to that switch (port monitoring) pretty secure. if it makes you feel better then you could give them each a second private IP address but the traffic will still go through the same switch and ports ( basicly same as what you have right now.

sorry i guess my question was pretty vague.



this is exactly how they are currently set up, but i'm not 100% sure they are on the same subnet.



see right now i'm not sure they are on the same subnet. how do I tell? but this is the situation i want, i want these 4 machines to be able to speak to each other without going past the switch.

when i run ifconfig on each, i get eth0 and lo on all but one, where i get eth0, lo and ppp0. ppp0 has an address of 192.168.234.235. what's up with that?

or maybe i have no idea what i'm talking about...

i just wonder if i connect between two of my computers on that rack if that counts for bandwith charges, because the way it sits now to transfer data between computer 1 and computer 4 i have to go through the switch, which i assume is where they measure bandwidth. that's really what i was driving at. i guess i just need to talk to the data center. bah, i hate leasing computers, you never really know what you are going to get.

this is where you need to know what they have configured for you. for instance if they are all on same subnet then it never gets past the switch. if they are on different subnets and it is a normal layer2 switch it will get pushed to the switches default gateway router which will push it back to the correct vlan on that switch. if it is a with routing capability ( like cisco 3550 or bigger) then the switch will route from one vlan to the other and hence never go past the switch.
You need to talk to your host and ask them how they are billing (at what point), and how your equipment is connected.