Problems configuring a private network using 2 Centos boxes.

Issues related to configuring your network
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Posts: 6
Joined: 2007/03/03 06:37:07

Problems configuring a private network using 2 Centos boxes.

Post by Paddyman » 2007/03/15 00:27:24

Hello every one. I am new to linux and networking in general. From reading articles online I decided to set up a small private network at home for learning purposses. I have never setup a network in my life before

I have both a public network and a private network.
I have 2 PCs with Centos4.4 installed in both. Each has 2 network cards. 1 normal 10/100 ethernet card and one GigE card.

The puplic network consist of:
1 Machine which is my destop is connected to a router using normal 10/100 ethernet card which then connects to the cable modem. The desktop is connected to the only monitor. The internet connection works good.

In the private network:
The GigE card on the desktop machine(which is the second network card on that machine) is connected to the other GigE card in the second machine which is the server. The server is not connected to the router, thus does not access the internet. The server is not also connected to a monitor. My network link b/w the desktop and the server is CAT6 which is connected to both ends of the GigE card. The 10/100 nic port on the server is not connected and its empty.This makes the private network.

This means I have two separate networks:
One with the desktop going out to the internet(small) and the second with
the desktop and the server using CAT6.

This is how my physical connection looks like:
So, (for 10/100 ethernet on my desktop) I have plug desktop->router->modem.
The server((GigE port)) is plug into the 2nd ethernet port(GigE port) on my desktop using CAT6
Right now I can connect to the internet from my desktop b/c is connected to my router but I don't know how to connect to the 2nd computer (server).
How do I make both computers to communicate using the GigE on both machines? I am begging for help here please. Please could some one help me out to configure both machines such that they could communicate with one another? I would really appreciate your help.

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Re: Problems configuring a private network using 2 Centos boxes.

Post by pjwelsh » 2007/03/15 15:36:10

Cool. Welcome to Linux and CentOS! The connection of the 2 GigE's should be pretty basic. You just need to make sure that you set up each of the GigE cards with a common network address and unique IP. So GigE of desktop could be something like and the server's GigE could be both with a netmask of That is a *start*. By default, you should be able to use "ssh" from the desktop to the server. I would suggest something like "ssh -l root -X". That is *IF* you want to go over as user "root" and tunnel X11 (gui tunnel).

This realy gets much more for now. I bet you would like to give the server access to the internet also. Well you will need to turn your desktop into at least a router (iptables). You should google for good info. Use a search of "iptables router rules" or "iptables NAT rules" and you'll get info like for that.

Typically, however, the server is the firewall and the desktop is behind it. Your current setup will give you a better chance to play since the desktop can google without issue.

Please take a bit of time to read some of the very good tutorials from the "Information" link or go to

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Location: San Francisco, CA

Problems configuring a private network using 2 Centos boxes.

Post by michaelnel » 2007/03/16 16:14:24

I agree with pjw's excellent advice... but there is one other thing. If connecting two machines directly together (without a hub or switch in between), you need to use an [url=]Ethernet Crossover Cable[/url]. I believe some recent gigabit interfaces are auto sensing and therefore don't require a crossover, but personally I'd get one and MARK IT as a crossover cable.

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