[CentOS] Network configuration question

Gregory P. Ennis PoMec at PoMec.Net
Sun Feb 17 16:39:45 UTC 2008


On Sun, 2008-02-17 at 08:33 -0700, David G. Miller wrote:
> 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
------------------------------

My thought is the dame as Dave's.  You should be able to do this easily 
with iptables with your wired eth functioning as an internal network and
your wireless eth functioning as the external connection.  

You also may be able to get away with using a switch instead of a cross
over cable if your switch automatically senses the connection... some
switches do this and some do not.

Good Luck!!

Greg



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