Its possible that the Knoppix Kernel puts eth0 and eth1 the other way round.

You can get some information about your network-cards by typing

ifconfig -v

...and with

lspci -v

you can get some information about all installed pci devices. Thus You can compare the Interrupts, or with only ifconfig check out the mac adresses to exactly identify which device is eth0 and which is eth1.

Or maybe You just give it a try to config eth1...