Ubuntu Manpage: pppoe-sniff - examine network for non-standard PPPoE frames

NAME

       pppoe-sniff - examine network for non-standard PPPoE frames

SYNOPSIS

       pppoe-sniff [options]

DESCRIPTION

pppoe-sniff listens for likely-looking PPPoE PADR and session frames and deduces extra
options required for pppoe(8) to work.

Some DSL providers seem to use non-standard frame types for PPPoE frames, and/or require a
certain value in the Service-Name field. It is often easier to sniff those values from a
machine which can successfully connect rather than try to pry them out of the DSL
provider.

To use pppoe-sniff, you need two computers, a DSL modem and an Ethernet hub (not an
Ethernet switch.)

If the DSL modem normally connects directly to your computer's Ethernet card, connect it
to the "uplink" port on the Ethernet hub. Plug two computers into normal ports on the
hub. On one computer, run whatever software the DSL provider gave you on whatever
operating system the DSL provider supports. On the other computer, run Linux and log in
as root.

On the Linux machine, put the Ethernet interface into promiscuous mode and start pppoe-
sniff. If the ethernet interface is eth0, for example, type these commands:

ip link set eth0 promisc on
pppoe-sniff -I eth0

On the other machine, start your DSL connection as usual. After a short time, pppoe-sniff
should print recommendations for the value of PPPOE_EXTRA. Set this value in
/etc/ppp/pppoe.conf.

After pppoe-sniff finishes (or you stop it if it seems hung), remember to turn off
promiscuous mode:

ip link set eth0 promisc on

OPTIONS

       -I interface
              The -I option specifies  the  Ethernet  interface  to  use.   Under  Linux,  it  is
              typically  eth0  or  eth1.   The  interface  should be "up" and in promiscuous mode
              before you start pppoe-sniff.

       -V     The -V option causes pppoe-sniff to print its version number and exit.

BUGS

       pppoe-sniff only works on Linux.

AUTHORS