My friend Jason use ADSL and his Ubuntu9.10 machine can not connect to internet with the default network-manager come with Ubuntu 9.10.Everytime the machine startup,he need to type pppoeconf command and configure to access to internet.Here is how to fix this problem in Ubuntu 9.10.

Step1:Update Network Manager to the latest version from PPA

Open up terminal from Applications->Accessories->Terminal to type following command to add the key first:

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys BC8EBFE8

Edit /etc/apt/sources.list by this command:

sudo gedit /etc/apt/sources.list

append following to end of the file and save it.

deb http://ppa.launchpad.net/network-manager/trunk/ubuntu  karmic main
deb-src http://ppa.launchpad.net/network-manager/trunk/ubuntu karmic main

Now,type this two command to update the network-manager:

sudo aptitude update
sudo aptitude safe-upgrade

Step2:configuration to fix the conflict between pppoe and network-manager

Edit /etc/NetworkManager/nm-system-settings.conf

sudo gedit /etc/NetworkManager/nm-system-settings.conf

find and change “managed´╝Łtrue” (without quotes).

Edit /etc/network/interfaces,

sudo gedit /etc/network/interfaces

change its content to:

auto lo
iface lo inet loopback

Delete /etc/resolv.conf by this command:

sudo rm -rf /etc/resolv.conf

Now,restart machine or restart the network-manager by this command:

sudo /etc/init.d/network-manager restart

Step3:Add DSL connection to network-manager and make it auto-connect at login.

Right click on network-manager icon and select “edit connections”
network-manager

Delete useless connection.In DSL tab,click Add and then input your Username and Password.
network-manager1

Remember check the “Available to all users” (marked in picture) to prevent┬á keyring locked problem.