Niki Kovacs wrote:
> Hi,
>
> My wife and I live in a two-storey flat, and we have a small home LAN
> (100% CentOS 5) with a "classical" configuration:
>
> On the ground floor, there is the telephone jack with the DSL modem
> router (192.168.1.254). This modem has a mini-switch with two Ethernet
> jacks to it, and the two are used by:
>
> - the server (192.168.1.1), a "black box" running in a cupboard 24/7
> - the wireless AP (192.168.1.253)
>
> Then, on the first floor, everything is connected by wireless, and for
> the moment, configured statically:
>
> - my desktop PC (192.168.1.2)
> - my laptop (192.168.1.3)
> - my wife's laptop (192.168.1.4)
>
> 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?
>
> Any suggestions for that?
>
> Cheers,
>
> Niki
This one qualifies for "There's more than one way to skin a cat". Your
final thought is what *I* would do; indeed, what I have done to share a
dialup connection before DSL was available here.
1. Leave your current working LAN untouched.
2. Physically connect your desktop PC and the older laptop with a
rollover cable.
3. Create a second network on your desktop PC using eth0. 192.168.2.1
would work fine.
4. Add the laptop to the new network, assigning it 192.168.2.2 (or whatever)
At this point, you should be able to ping the desktop from the laptop
and vice versa.
5. Forward the new network to the old one. On the desktop, as root, enter:
# echo 1 > /proc/sys/net/ipv4/ip_forward
6. You should now be able to access the Internet from the hard-wired laptop.
7. To make the change in (5) persist across reboots, etc., edit
/etc/sysctl.conf as root and change
net.ipv4.ip_forward = 0 --to-- net.ipv4.ip_forward = 1
As far as the rollover cable, I was fortunate enough to stumble upon
some RJ-45 reversing couplers so that I never have to worry about the
"here it comes" and "there it goes" pairs. Saves wear & tear on
crimpers. :-)