Richard Hutnik wrote:
A concern of privacy over the Internet is that people will steal
packets going from one IP address to another one.

Which is only possible if either a) one is located between the source
and destination systems, or b) one has control or can take control of
a system located between the source and destination. That also assumes
that the route between source and destination doesn't change in such a
way that you're no longer located along the route.

Perhaps someone could illuminate me here. Wouldn't it be possible to
use this ability to have a cheap way to broadcast sound or video over
the Net to a large number of people, without taxing bandwidth? It
would be unidirectional, but so is radio and television broadcasting.
Have one machine do streaming audio and video in an unsecure VPN and
have other people "tune into" this network and pull the stream packets
off the network.

What you're proposing is really no different than one source system
supporting a large number of streams. The only difference is that
it starts as one stream, but ultimately splits off into a large
number of streams (to support your "large number of people") at
one or more points somewhere downstream of the source. Doesn't
really make much difference as far as overall bandwidth is concerned;
the stream still has to be split to reach everyone. The old
net.acronym TANSTAAFL ("there ain't no such thing as a free lunch")
definitely applies here.

IP multicast has some of the properties of your scheme, and is
structured in such a way as to keep bandwidth usage as small as
possible. A stream subscription service that used IP multicast
is conceivable technologically, but the logistics required to scale
it up for true mass consumption while maintaining full efficiency
would be difficult to pull off without support from the major ISPs
and backbone carriers, and there's just no financial incentive for
them to do so, at least not as things are structured now.

-Shawn Mamros
E-mail to: mamros -at- mit dot edu