[NTLUG:Discuss] DSL vs. Cable modem

[Greg Edwards]

MadHat wrote:
> 
> This has been an argument for a long time, like since the cable modems
> came out.  The argument isn't that cable modems are unsecure per say,
> but that the networks being set up by the cable companies are insecure.
> With the cable modems, they are suposedly using a simple routing scheme,
> where the traffic is sent to a pop for you neighborhood and then
> broadcast to that network, so that anyone in your neighborhood would be
> able to capture all your network traffic and therefor get your user
> names and passwords.  This could happen a lot of places if the network
> infastructor was not designed for security (not just with cable).  You
> can set up your firewall, but you can't protect yourself once outside
> the firewall.  I have not hooked up eith DSL or Cable yet, so I can not
> speak from experience, but only from what I have read.  Supposedly, with
> DSL they are using smart switches such that you only get the traffic
> intended for your node, rather than for every node on the switch.  I
> don't know if the technology hasn't been ported to cable, or if the
> cable companies just didn't want to spend the extra money, but this is
> the issue I have always heard about.
> 
> --
> MadHat
> 
> _______________________________________________
> http://ntlug.org/mailman/listinfo/discuss


Between your modem and the ISP there is not and cannot be any way to
hide your traffic.  No matter how the ISP sets up a cable modem it still
receives data over a coax that is shared among everyone that is on the
same cable.  They have the same physical characteristics as a 10Base2/5
ethernet, coax is coax.  Even if your ISP encrypts the data it is still
carried on a coax shared by several systems.  Your modem has to view
every packet that is sent to determine which has your address as its
destination.  Yes it is possible that a cable company could send a
different signal level to every cable modem that shares a segment of the
line, then again it's possible I could sell Brooklyn's favorite real
estate to someone over the age of 10:)

An xDSL line is a point to point circuit.  Between you and the CO DSL
only
carries a single signal.  DSL works over standard telephone lines just
at
a different signal level than your analog phone.  That's the real reason
that DSL is distance and line condition sensitive.  The reason that the
telco won't guarentee the transfer rate above the CIR is that past your
connection at the switch it jumps on a frame-relay circuit.

The only way to view the data passed between you and the CO on a DSL
line
is to tap into the line.  On a cable modem you are automatically tapped 
into the line if your in the neighborhood:)

-- 
Greg Edwards
New Age Software, Inc.
http://www.nas-inet.com
(972)393-4907