problems with ppp0 and eth0

[Francois Massonneau <frmas free fr>]

Hello,

I have a problem using my laptop to establish a connection between it
and my lan and the internet.
This is what I can describe and I really don't know where to look at
to solve it.

Once my laptop is up and running, I can "ping" another computer of my
LAN with no problem at all. It works fine.
But if I fire up kppp to call my ISP, kppp died and give me that as a
log file :
Feb 25 19:16:29 earlene pppd[1450]: By default the remote system is required to authenticate itself
Feb 25 19:16:29 earlene pppd[1450]: (because this system has a default route to the internet)
Feb 25 19:16:29 earlene pppd[1450]: but I couldn't find any suitable secret (password) for it to use to do so.
Feb 25 19:16:29 earlene pppd[1450]: (None of the available passwords would let it use an IP address.)

If I do a "ifdown eth0", I have no problem at all to call my ISP.....

BUT ...

If I do the same process : I start my laptop, then, I ping another
computer on my LAN, and it works as before, so no problem.
Then I open a terminal, and type "ifup ppp0" to establish a
connection on the Internet. The connection is established with a very
good speed, and I have no problem. So it shows me that I can have a
connection to the internet and a connection to another computer of my
lan AT THE same time. (so with the same config).
THen, if I stop the connection to the internet "ifdown ppp0", (the
ping process is still running as I didn't stop it), then fire up
kppp, I have no problem to reconnect my ISP, and so, kppp runs
smoothly WITH a ping running in the background.

Where this could come from ? Do you have an idea ? Thank you. Francois