[CentOS] Network configuration question

[David G. Miller]

Niki Kovacs <contact at kikinovak.net> wrote:

> I have an older laptop here, a Fujitsu Siemens Amilo D, that I'd like to 
> use as a simple build box. It's physically installed next to my desktop 
> PC. It doesn't have a wireless card, so I vaguely thought: is it somehow 
> possible to connect this laptop with an Ethernet cable to my desktop 
> PC's unused Ethernet card, and then connect it to the internet? In that 
> case, I wonder if I have to bridge the desktop PC's network interfaces 
> (wlan0 and eth0). That said, I don't even know if the driver for wlan0 
> (rt61) allows any bridging. Or maybe simply configure a different 
> subnet, but then, what would the network configuration look like on the 
> laptop and on the desktop PC?
You need what's called a crossover cable between the laptop and your 
desktop.  Think of a crossover cable as being like a "null modem" built 
into the cable for networking.  The tx wire at one end becomes the rx 
wire at the other for all wires in the cable.  This will allow the two 
systems to "talk".  The laptop's LAN settings should be set to have your 
desktop as it's gateway and I think you'll need to manually add a host 
route on the desktop for the laptop using the wired NIC as the interface.

You'll have to Google or get more advice from the list if you want to 
have the laptop be able to get onto the internet.  It should be possible 
to set up your desktop to route packets from the laptop through your 
wireless LAN.  I just don't know how.  If you can't get the wireless NIC 
to bridge with the regular NIC, it should be possible to do something 
with iptables rules to just forward packets that aren't for the desktop 
to your wireless modem/router.

If you're trying to get this done over the weekend, respond to me 
directly if you have any questions.  I get the CentOS list as a digest 
so I won't see any other questions until Monday.

Cheers,
Dave

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