I have just been through a slow learning process getting my dialler
working. It is fine. The experience of newbies with difficulties
understanding may be harder to capture than the finer points of hardware
and software.
Therefore I am putting together an explanatory text that might help.
Please feel free to comment or advise corrections.
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Overview: Using Linux as a base for dialling Internet Service Providers
Many may want to use their computers this way when travelling away from
their normal home base and its broadband or cable connections. This
write-up is intended to help you to understand what steps you are
completing as you going through the installation and setup procedures.
Then, when something does not work, you may find this a helpful guide as
to what is missing or disconnected.
Background
1. Modems used with computers are usually proprietary products for
which the manufacturer has inserted some technology that is
considered a trade secret. For this reason, manufacturers are
reluctant to issue copies of the software needed, for fear that
the secrets inherent in the modems are revealed.
2. The proprietary nature of the software then means that it cannot
be included in distributions of linux (such as Debian or Ubuntu,
Red Hat or SUSE) since everything in these distributions is
always open and free to be copied by any and all users. To
preserve this fundamental basic rule, indeed foundation, of
linux, users who want to connect through modems have to find and
install certain proprietary programs for themselves.
3. Modems are connected through files kept in the /dev directory.
This is a dynamic directory which is generated by the linux
kernel when it is booted and loaded. The reason it is dynamic is
that for the modern Plug and Play connection of units
(particularly modems on USB wires, or modems plugged into
through PCMCIA ports), the operating system has to assemble a
set of device files that suit what is going on. The files in
the /dev directory are lost when the computer is shut down, and
therefore have to be regenerated when the computer is started
up
4. Programs going by the family name of AGRSM have been written to
handle the needs of modems made by Agere corporation. The most
common of these is the 011c11040 model. For it, the program
AGRmodem (hereafter written as “agrmodem”) has been prepared and
will be accessed by linux through the file name of /dev/modem.
Rather than use that standard name /dev/modem, however, it is
preferable to use a special name for this manufacture such
as /dev/AGR1, or /dev/AGR3.
5. These driver programs are intimately connected into the linux
kernel. They have to be regenerated whenever the kernel is
rebuilt, which needs to be rather frequently. It would therefore
be valuable to have something that does the regeneration
automatically, whenever the kernel is regenerated. That has been
written, too. “dkms” is the program that lives in the kernel and
invites (flags the need for) the regeneration, while dkms-agrsm
is the one that actually will do the regeneration, when so
invited.
6. In addition, all modems work through one of the serial ports in
the computer (in DOS and Windows these are called COM1, COM3
etc.) Therefore Agere Corporation has prepared a matching
program to handle the connection of the 11c11040 modem through
the serial port it will use. Handling this requirement in a
similar way, this program is to be placed in /dev/SAGR – short
for serial port of AGERE modem system.
7. At this point, we could dial the internet service provider and
type in our signon code and password when the ISP answers the
phone; then press a button to get the modem program to start
exchanging data through the serial port. However, it is easier
and more consistent to store the signon codes and password in a
dialler program. So we will need to set that up too. The
password has the added requirement that we have to store it in a
secret, hidden place.
8. We therefore require the following:
a. The programs agrmodem and agrserial. These programs are also
called “drivers”. Operating versions have the suffix “.ko”
b. A program to pick up the master copy of these driver programs
and put them in the /dev directory when the computer is booted.
This is called “agrtools”.
c. An instruction that the computer is not to use /dev/modem but
the equivalent address of /dev/AGR3. These instructions are “ln”
symbolic links.
d. For the dialler program we could use “wvdial” directly or Gnome
PPP with is a GUI presentation of the same thing.
e. “dkms-agrsm” needs to be installed, waiting and connected, for
whenever the kernel is regenerated.
Now you can proceed into the details
(Observations: wvdial.conf is not a very secret
place. /etc/ppp/pap-secrets has root read locks on it. But wvdial.conf
which is without any lock, and holds the ISP access passport in clear.
That is why this configuration reference file is put into /etc. So that
it will need root to handle or change it.
It is not quite clear to me why wvdial.conf says “Modem = /dev/ttySAGR”,
when we are not going to use that. We are putting in the links, why not
use /dev/modem, or even go direct to /dev/ttyAGR3.
I have not put in anything about the linux headers since I do not quite
follow that part yet.
I have not explained what HDA stands for
I also do not follow the ALSA issue, but suppose AGRSM needs to
neutralize the sound card outputs.
What would be the most useful place to send this?)
mng 2009/02/13
