ethernet bridge

[ultramagnetic]

Hi,

I need to set up a 3-PCs test-environment, two PCs running on Windows and the one in the middle on Linux (Ubuntu, Kernel 2.6.10). I want to send data between the two win-PCs, which will be disturbed by the linux-machine (I installed Nistnet for that purpose).

The Linux-PC has 2 Ethernet-Cards. Eth1 is connected to a switch, which is connected to a internet-router and the first Win-PC. Eth0 is connected to a Windows-Laptop via Crossover-cable.

The network on the one side uses 192.168.0.XXX-addresses, and I configured the Win-Laptop to use a 10.0.0.XXX-address. I can ping the linux-machine from both windows-PCs, but the two windows PCs can't ping or connect to each other.

I already tried to configure it with "iptables", but without success. Do I need to install a Ethernet-Bridge?

Sorry if that sounds like a standard newbie-problem, but I already googled a while and couldn't find answers.

I would be a really great help if someone could help me out.

thanks,

chris

[drakebasher]

You need to create a route from the 192.x.x.x network to the 10.x.x.x network and vice versa. Look it up, but I think you will need something like this for your Linux box:

route add -net 192.168.0.0 dev eth0
route add -net 10.0.0.0 dev eth1

That will default to netmask 255.255.255.0 and 255.0.0.0 respectively, I think, unless you specify a different netmask in the route command.

And you need to have IP forwarding in your kernel.

[ultramagnetic]

thanks for the quick reply!

I tried it out, but I get the error message:
"SIOCADDRT: Invalid argument", but the arguments are valid and conforming to the "man route".

Another strange behaviour: from the first Win-PC, I can't ping the linux-PC if it has no connections open. e.g. I run the ping command on the win-PC, and get request timed out, but if i start to surf the web or ping back on the linux-machine, it works

[ultramagnetic]

how can I test if I have IP forwarding in my kernel?

[drakebasher]

Try this link.

[ultramagnetic]

ok, it works. thanks for your responses. Finally, all that I had to do was to set the ip_forward to "1" and to add a new route on the windows-pc via the linux-machine.