Someone has to know something..
I saw on another linux forum my problem but I cant find a way to do it in knoppix. This is what it says to do

I'm using my phone co's adsl service also, and also using Westell Wirespeed w/RH9 you don't need any software to run it. just go to Main Menu-> System Tools-> Network Device Control, if that eht0 is what you have set up delete it. Click add under service pick xdsl and give it all you logon info and anything else you have after that click activate and run a browser.

My pppoe set up has the eht0 and thats my home network not the internet connection.. Anyone please tell me how to do this in knoppix..