What the output suggests is that the integrated nic has not been recognized by knoppix, so a couple of things to look into.

The output of: lsmod will tell us if the kernel module (driver) for the nic has been loaded. You should look for something like uli526x. If it's not there you can try loading it manually, if it comes with knoppix, by typing: modprobe uli526x.

If that seems to work then proceed with ifconfig eth0 up etc. If it does not, then you can either try and find and download the driver or find a live CD distro, that has it already, Ubuntu and Kanotix come to mind, and especially considering that they have 64 bit versions.