When Ubuntu 9.10 releases, pppoe connection via NetworkManager is impossible because some bug in it. So I switched to the traditional but workable way – pppoeconf, now the problem seems to be solved when using nm team PPA, so I plan to turn back.
But during my process, there are some other problems. Firstly nm cannot handle the connections automatically; secondly we cannot edit connections system wide.
Here are the correct steps:
First, add “NetworkManager daily trunk builds for ubuntu” PPA:
deb http://ppa.launchpad.net/network-manager/trunk/ubuntu karmic main
deb-src http://ppa.launchpad.net/network-manager/trunk/ubuntu karmic main
Second, comment out line “exec pppd call dsl-provider” in /etc/ppp/pppoe_on_boot, that is to say disable my previous “pppoe on boot” setting which is configured by pppoeconf.
Third, rename /etc/network/interfaces to backup file. NetworkManager will only handle connections which haven’t declared in interfaces, if you didn’t any tunning on such file, you can delete it, but backup before doing any change is a good habit, :)
Forth, edit /usr/share/polkit-1/actions/org.freedesktop.network-manager-settings.system.policy , find out the line contains “System policy prevents modification of system settings”, and below it there is a “
Fifth, reboot your system, because these settings won’t take effects even though you have run “sudo services network-manager restart” and “sudo services networking restart”.
Now it is working on my system, cheers!