🚀 go-pugleaf

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?