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for debugging why my router wasn't connecting to pppoe i've tried to connect via the pc, it worked, then i started wireshark just to see what was going on, and i've seen that i can read all the PADI packets from ISP's other clients, now i'm thinking, is that a security problem? Can another user respond with a PADO packet and complete a pppoe session acting as gateway and maybe also sniffing pppoe credentials?

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I remember an Article on the German news site which described a similar vulnerability at a German DSL provider:

The problem in that case was, that not only all the PPPoE packets were visible, but all packets. So if connected directly to a Windows computer, Windows would autoconfigure a private ip-address in the range. Furthermore since this is another interface, Firewall rules for the internet-connection were not applied, exposing the Windows Network file and printer sharing.

So this is the next thing to check.

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I've just tried to run a pppoe-server and got full padi, pado, padr, pads handshake, ending with a padt due "RP-PPPoE: Child pppd process terminated" maybe because the server isn't configured for authentication or other things. Usually i can just see padi, just because they're in broadcast, but i can still send packets with the correct mac to another client. Btw i'm using a kind of wimax connection, not a normal dsl service. – Alessandro Jul 13 '11 at 23:18
You think that's a security problem? – Alessandro Jul 13 '11 at 23:20
Btw, i cannot directly connect to others pc because i just know the mac and not the ip (due the padi broadcast) so i can just send low level packets – Alessandro Jul 13 '11 at 23:27

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