How can I remove pppoeconf settings ?

Though this is just a shot in the dark, you could try and remove pppoeconf

sudo apt-get remove pppoeconf

Though it seems kind of odd to me because firestarter 'should' work with pppoeconf

In case that doesn't work as is, you might want to add the --purge option ie:

sudo apt-get --purge remove pppoeconf

which should remove any configuration files associated with pppoeconf

I've considered before removing the package, but it also requires the removal of ubuntu-standard, what can give me in the future problems for upgrading to newer versions.

Besides that, after removing pppoeconf, what if I start to use a ADSL provider again ? I would'nt have pppoeconf to connect and neither internet do download the package.

Removing the package might work but doesn't seem to be the proper solution. Anyone knows a more surgical approach ? I inted to document this process properly for future users in the same situation.

OK, what's the exact error message you get when you try to start firestarter? I've just installed firestarter alongside pppoeconf and it doesn't complain about pppoeconf.

Instalando firestarter (1.0.3-1.2ubuntu3) ...
 * Starting the Firestarter firewall... ppp0: erro obtendo informações da interface: %s: dispositivo não encontrado
ppp0: erro obtendo informações da interface: %s: dispositivo não encontrado
ppp0: erro obtendo informações da interface: %s: dispositivo não encontrado
                                                                         [fail]
invoke-rc.d: initscript firestarter, action "start" failed.
dpkg: erro processando firestarter (--configure):
 subprocesso post-installation script retornou código de saída de error 2
Erros foram encontrados durante processamento de:
 firestarter
E: Sub-process /usr/bin/dpkg returned an error code (1)
A instalação de um pacote falhou. Tentando recuperar:
Instalando firestarter (1.0.3-1.2ubuntu3) ...
 * Starting the Firestarter firewall... ppp0: erro obtendo informações da interface: %s: dispositivo não encontrado
ppp0: erro obtendo informações da interface: %s: dispositivo não encontrado
ppp0: erro obtendo informações da interface: %s: dispositivo não encontrado
                                                                         [fail]
invoke-rc.d: initscript firestarter, action "start" failed.
dpkg: erro processando firestarter (--configure):
 subprocesso post-installation script retornou código de saída de error 2
Erros foram encontrados durante processamento de:
 firestarter
ktk@ktk4:~$

As far as removing the package, yes, it's probably not the cleanest of ways, but it may just work for you, and the package is on the CD in case you need to install it again. Though it doesn't seem that it is the package that is the issue.

Yeah, I don't think it's an issue with pppoeconf being installed.

The postinst script seems to be dying. It doesn't seem to be able to get information about the ppp0 interface, but my Portuguese isn't that great :) If you could translate the "dispositivo não encontrado" bit, I might be able to help a bit more.

I always thought that translating error messages would turn someday into this. I think erros should be followed by an ID number, so anyone could read it in your own language in situations like this.

Dispositivo não encontrado = Device not found

Thanks, I wish I could get around to learning a few more languages...

Anyway, I think the problem here is an old configuration file for firestarter that nominates ppp0 as the interface used. (Check the file /etc/firestarter/configuration if you're interested.) Removing and purging firestarter and then reinstalling should fix this ie:

sudo apt-get --purge remove firestarter
sudo apt-get install firestarter

Let us know how that goes