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[LONG] ppp-udeb: A succesful installation using it, some ideas and some requests for advices

Hello all,

I have some good news regarding ppp-udeb and PPPoE. As the subject
says, I have managed to conduct an installation over PPPoE using the
patched ppp-udeb I have created and a customized image[1].

The good news:
- the pppoe connection was configured and packages were downloaded
from the internet over that connection
- the ppp-udeb has appeared within the additional components list

The bad news:
- there seem to be some problems with pppoe modules not being loaded
automatically (must I add „modprobe pppoe" in the postinst? if so, how
do I keep the output from interfering with debconf?)
- there are some weird side effects (probably due to messages being
spitted out to stderr or stdout in the postinst); what should I do
with the error messages? I would like to have errors logged in the
syslog, but it looks to me that I should direct stdout messages to
/dev/null so it does not interact with debconf
- the postinst starts multiple connections if the step is run
multiple times, so is not policy compliant and it should changed to
detect running connections on the interface which will be used (a
little bit tricky for multiple net card systems)
- if the pppoe connection fails, then that is silent; no message is
given which is bad
- the dialog boxes for username and password are asymetric (entry
fields way close to the left margin) and the title of the dialog is

There are some problems which are a little bit more complex and I am
asking for advice:
a) the pppoe connection detection should it fail silently on a normal install?
b) when should the ppp-udeb postinst should be ran? after or before
dhcp (fails)?
c) what should be done for systems with multiple network cards?
d) how can the pppoe software be added automatically to the target
system (in case the pppoe configuration succeded during the
installation it would make sense to have it configured in the target
system, too)

The way I am thinking the PPPoE configuration should be done/integrated in d-i:
- if dhcp fails, try the detection of concentrators (implies running
ifconfig ethX up)
- if concentrator detection fails, drop to manual configuration
- if a concentrator is found on a card, request user input regarding
username and password for the PPPoE configuration
- try the configuration with the given data
- in case it fails, drop a fat error message (requesting the info to
be reinserted?)
- in case configuration succedes, then everything is fine

Please comment (my explanation and more questions are below).

The pppoe and dhcp protocols are orthogonal, so if one configuration
succedes on a card, there is no way the other will. So the question
is, when should the PPPoE configuration be attempted? It seems logical
to be attempted after dhcp has failed because it will mean that less
input will be necessary on default installs.
But that, AFAIK, would lead to an unnecessary step in the
configuration and the imposibility to run the PPPoE configuration
directly from the d-i menu. Is this a real problem?

The PPPoE protocol works with the so called concentrators which could
be detected automatically which would mean that for Ethernet cards
which are not supposed to connect to PPPoE servers for configuration
the pppoe questions could be omitted and the installer should be
directed to static configuration. I am not sure if there are cases in
which the concentrator is not detected, but I fear that in the case in
question the whole configuration will fail altogether.
The detection of the concentrators and the actual configuration can't
be made in deifferent postinst scripts, so would it make sense to
return 0 as an exit code from the ppp-udeb postinst if no
concentrators are found?

Once the configuration is made for one card, should it be attempted
for others, too? This is a little bit difficult and I fear there are
not so many practical cases in which it will apply, if none.

In systems with multiple cards, I don't think there is a way to know,
after the configuration has been done, on which Ethernet card the ppp
connection exists, so if the postinst is ran multiple times there are
issues related to determining which pppd process corresponds to which
etherenet card.
I probably the concentrators detection could be ran again, but should
the current ppp connection be dropped, if it exists?

In case the PPPoE connection fails, should the user be given the
chance to configure the card as static? Note that if the concentrator
is found it shouldn't make sense and it might be possible that the
configuration data was given incorrectly.

There is small issue, if the concentrator is searched on a card, then
the card in question must be "ifconfig CARD up" with no IP, should
this be restored if the concentrator is not found? Would it affect the
static configuration?

How can the configuration information be copied to the target system
after the system is installed?

[1] using instructions at http://wiki.debian.org/DebianInstaller/Modify

"Imagination is more important than knowledge" A.Einstein

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