If you're having problems with KPPP and "pppd" aborting because of an error, "Cannot determine ethernet address for proxy ARP" then you can disable proxy ARP.

To do that, edit "/etc/ppp/options" and comment out the line that says "proxyarp". If you want to enable or disable proxy ARP for a specific PPP connection then edit the KPPP connection settings. Click on the "Dial" tab and then click the button that says "Customize pppd Arguments". You can add either "noproxyarp" or "proxyarp" to override what is in the "options" file.

It's probably a good idea to disable proxy ARP on a laptop, though you might want to leave it enabled on a desktop. Proxy ARP allows the remote computer on the dialup connection to communicate with computers on the LAN. You might want to do that if you use the dialup connection on your desktop computer to access another private LAN.