ADSL connection doesn't work

[Vincent Lefevre <vincent@vinc17.org>]

I've tried to connect a PC (Debian testing) via ADSL, but I can't
make the connection work.

First, I've tried pppoeconf, but it says:

          x Sorry, I scanned 1 interface(s), but the Access          x 
          x Concentrator of your provider did not respond. Please    x 
          x check your network and modem cables. Another reason for  x 
          x the scan failure may also be another running pppoe       x 
          x process which controls the modem.                        x 

I've also tried by configuring the /etc/ppp/peers/dsl-provider file
(setting the 'user' option, trying 'pty "/usr/sbin/pppoe ... -m 1412"',
and demand-dialing) and executing the /etc/ppp/ppp_on_boot.dsl script,
but this doesn't work. A 'ifconfig -a' shows eth0, lo and ppp0, and
more precisely for ppp0:

ppp0    Link encap:Point-to-Point Protocol
        inet addr:10.64.64.64  P-t-P:10.112.112.112  Mask:255.255.255.255
        UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1492  Metric:1
        RX [...] (all 0)
        TX [...] (all 0)
        collisions:0 txqueuelen:3
        RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

The 'LAN', 'Line TX', 'Line RX' of the ADSL modem (Alcatel Speed Touch
Home) are always off. The Ethernet card is a nVidia on a K7N2 (MS-6570)
motherboard and I use the driver from

  http://www.nvidia.com/view.asp?IO=linux_nforce_1.0-0256

Note: When the PC is connected to the modem via a router (so, not
using PPPoE on the PC side), there are no problems. This eliminates
many possible problems (cables, modem...).

Any idea?

TIA,

-- 
Vincent Lefèvre <vincent@vinc17.org> - Web: <http://www.vinc17.org/> - 100%
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Work: CR INRIA - computer arithmetic / SPACES project at LORIA