Quote Originally Posted by CapNemo
i tried what you suggested and enabled dhcp on the router.
knoppix couldn't assign an ip address while booting, and network-setup couldn't either later on.
if i enter the values manually again, i get the same results.Nemo
By network-setup I hope you mean netcardconfig, but I wanted to ask. I think were's going to have to be very exact on or terms and keywords if we are going to track this down and not make assumptions about what the other is saying.

With the router's DHCP enabled and Knoppix booted without the nodhcp cheat code, try the two following commands from a shell "sudo mii-tool -r" and "netcardconfig". When Netcardconfig starts, take the YES option. Please post back the exact text of any errors.

I'm still hoping that ethereal might be giving you some insight, as I do have doubts that the above will tell us that much. Certainly your card is working fine if it can ping other local systems. It might help to post back the exact text of the result of the ifconfig command. You could also use ifconfig to change your mtu if you really think that could be an issue, but I don't see how it could be for a simple ping. And you might want to look at the man page for ifconfig for other inspiration.