security concerns with cable splitters

[cmerkel at gmail.com (Chris Merkel)]

Based on my understanding of how cable modems work on Time Warner and
Charter in the midwest, all they do validate if a device can talk on
their network is via cable modem. It's conceivable that a person could
clone a MAC address on a cable modem to gain internet access via the
unprotected coax, but that wouldn't get them anything other than a
public IP.

- Chris Merkel

2009/4/2 Nathan Sweaney <NSweaney at tulsacash.com>:
> I just received a question that I can't answer.??A customer has a cable
> internet service with COX that has only been used for internet.? The modem
> and all other networking equipment is locked away so that no one has access
> to it.? They've decided that they'd also like to have a TV in a public area
> for visitors to watch.? COX says to just add a splitter in front of the
> modem & run a cable to where they want it.??The crazy thing is that the
> customer actually considerd the security implications and asked ahead of
> time.
>
> So my question is, if an intruder had uninhibited access to the coax that
> was split off upstream from the cable modem, is there anything they can do
> with it?? I've been told by COX that it won't interfere with the?connection
> and that adding a second modem to the connection wouldn't work because it
> wouldn't be setup on their end.? However my bigger concern is the potential
> to intercept traffic.
>
> I know from past experiences that if you plug your coax into your VCR or
> satellite the wrong way you can actually deliver content to your neighbors
> (or at least cause a lot of interference), so that suggests that the
> connection doesn't just flow one-way.? So can the coax-splitters determine
> which way traffic is supposed to be flowing?
>
> I understand that even if it's "possible" it may not be easy or likely, but
> this network is used for processing credit cards so I want to make sure I
> have a complete answer.
>
> Any information or resources on this would be appreciated.
>
> Thanks
>
> - Nathan Sweaney
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-- 
- Chris Merkel