🚀 go-pugleaf

The signal of a cable modem is TDMA
The encryption is DES 56
"Kip Patterson" <ripatters@columbus.rr.com> wrote in message
news:3A77D75E.82B3CDB3@columbus.rr.com...
> Cable does not use CSMA/CD.  It has always, including the proprietary
Motorola system,
> used polling for the upstream channel.
>
> If you were to sniff on your cable, you could only see the downstream
transmissions,
> and the upstream transmission of those on your side of the next upstream
amplifier.
> There is no promiscuous mode on a DOCSIS modem, and you would have to be
able to
> decode the encryption, which so far as I know is used universally.
>
> Thanks for listening.
>
> Kip Patterson
>
> Lawrence Baldwin wrote:
>
> > John Navas wrote:
> > >
> > > [POSTED TO comp.dcom.modems.cable; PLEASE REPLY THERE]
> > >
> > > In <3A76B6CA.73B36B26@mynetwatchman.com>, Lawrence Baldwin
> > > <baldwinlSPAMMENOT@mynetwatchman.com> wrote:
> > >
> > > >I actually contend that DOCSIS cable (assuming encryption is turned
on) is more
> > > >secure than DSL.  Since DSL isn't encrypted, it can be packet sniffed
at
> > > >any (relatively unsecured) cross box or pedestal, albeit with a VERY
expensive
> > > >analyzer.
> > >
> > > Am I missing something, or are you just referring to encryption
between
> > > the cable modem and the CMTS?
> >
> > Absolutely.
> >
> > > If the latter, then traffic beyond the
> > > CMTS is unencrypted, and just as exposed as DSL traffic.  Both are
> > > secure on the local link;
> >
> > ADSL sure isn't secure on the local link, for reasons above.
> > If typical cable modem isn't encrypted, than agree it's equally
> > insecure.
> >
> > What irks me is when ADSL providers say: "ADSL is more secure than
> > because your connection
> > isn't shared between your home and central office".  I think it's
> > ridiculous to associate *shared* with *insecure* without obviously
> > taking the time to understand the issues.  Even worse, they're inferring
> > that the *unshared* = *secure* (from all threats), which is dangerously
> > mis-leading.
> >
> > I doubt packet sniffing the local link is a big concern anyway, so this
> > is really pretty moot.
> >
> > I guess my only big concern would be with cable modem...I've heard that
> > the modems get be put into an promiscous
> > debug mode and and start forwarding *all* traffic out the Ethernet
> > port.  This would be a real threat as it means
> > anyone with a shareware analyzer could Sniff.  If this isn't possible,
> > then you'd need a broadband analyzer, which would be out of most people
> > reach.
> >
> > >both are exposed on shared links beyond the CMTS/DSLAM.
> >
> > Agreed.  But presumably access to network infrasture is physically
> > secured at these layers.  Anybody can walk up to a pedestal and cross
> > box and jack in without much trouble.
> >
> > >
> > > I agree that most broadband ads are colorful nonsense.  Nevertheless,
> > > there is a real and important difference -- when the uplink saturates
on
> > > the typical consumer asymmetrical TCP/IP connection, downlink speed
> > > takes a big hit down to about the uplink speed (e.g., your 128/1500
> > > service suddenly becomes 128/128).
> >
> > OK, but what percentage of users are impacted by this.
> >
> > > On DSL, that affects *only* the
> > > subscriber's own downlink; on cable, that affects *all* subscribers on
> > > the shared segment.  It's the big dark secret that cable MSO's don't
> > > want to talk about, and the probable reason that servers are typically
> > > prohibited on cable, even with an uplink cap, but not on DSL.
> >
> > HUMMMM. VERY interesting point.  Basically one porn server in the
> > "neighborhood"
> > and the whole darn thing is down even though there's tons of downstream
> > bandwidth
> > available. ....hmmmm.... DSL is looking better and better every day.
> >
> > I have no hands-on experience with cable infrastructure internals, but
> > a lot of what you content would seem to depend on how cable is
> > throttled.
> >
> > I know that DOCSIS has the *capability* of defining transmission slots
> > such
> > that the cable is no longer a CSMA/CD shared Ethernet...however, I'm
> > pretty
> > sure that almost no one implements this.  Anyone know for sure??
> >
> > --
> > -------------------------
> > Lawrence Baldwin
> > Protocol Scientist
> > 678-624-0924
> > http://www.mynetwatchman.com - I'm under attack, now what?
>