On Mon, 2011-02-14 at 11:19 +0100, Pascal Hambourg wrote:
> Tixy a écrit :
> >
> > The server uses PPPoE to talk to the modem, which translates this into
> > PPPoA to get to my IPSs equipment.
>
> Are you sure of this ? Isn't your modem rather working as a plain
> ethernet bridge, just transparently forwarding the PPPoE traffic between
> its ADSL and ethernet ports ? If so, then it is an obvious security
> breach : it is a plain ethernet switch connecting your LAN to the
> outside world.
Thinking about this some more. Even with PPPoE, I can't imagine that the
DSLAM in the exchange would be set up to pass and route Ethernet frames
down my phone line which had MAC addresses of machines on my private
network or which were broadcast packets. Seems like that leaves the
telco network open to abuse.
Even if the telco network did this, would a home modem just pass these
frames through transparently to its Ethernet port?
Also, from an efficiency point of view, why send a 48 bits destination
MAC addresses down my phone line with each frame? (Or even a source
address?). Could use header compression like PPP does, but why bother
support it at all?
I confess I know too little about any of the facts of this to understand
how it all works. Time to do some research.
--
Tixy () The ASCII Ribbon Campaign (www.asciiribbon.org)
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