[Tfug] "Opening" a physical ethernet connection

[Bexley Hall]

Hi John,

On 5/1/2013 7:20 PM, John Hubbard wrote:
> On 5/1/2013 4:33 PM, Bexley Hall wrote:
>> On 5/1/2013 4:17 PM, Bender wrote:
>>> Why don't you really tell us what you are trying to do?
>>
>> Ideally, I want to be able to "unplug" a "physical ethernet
>> connection" (i.e., a *cable*). This prevents the service(s)
>> available on that connection from being accessed *and*
>> protects the fabric from "assault" (e.g., someone taking a
>> line cord and connecting it to the pins of the connector
>> thereby frying a port in an *expensive* switch).
>
> What about routing your connection through a cheap switch[1], and power
> it via a wall switch. Turn off the wall switch, the cheap switch looses
> power and cannot talk to the rest of the network. This only partially
> protects against your physical assault. If someone did plug mains power
> into the RJ45, then you'd be out a $20 switch, but not your fancier
> many-port managed switch on the other side.

Exactly -- as I said in my initial post:
      I *think* the easiest/cheapest way of doing this would
      be to insert a small (network) switch in-line and just yank
      the power to that device when I want to "open" the connection.

But, realizing this a bit of a kludge, I went on to ask if there
isn't some *other* device that, effectively, does the same thing:
      Is there some *other* device that is designed to "open" such
      a connection, on demand?

> If its vandalism that you are worried about I'd ask you to really think
> about whether someone plugging mains into an rj-45 is that likely. What
> is the technical knowledge needed to plug mains power into RJ-45. Does
> your average vandal have that much technical knowledge. The only place
> that I'd worry about knowledgeable vandals is high school technology

No, you worry whenever there is something that can potentially be
gained by these actions/attacks.  Adversaries are *amazingly*
clever at finding and exploiting seemingly innocuous vulnerabilities
in devices/systems!  I've seen "customers" use small, solid state
strobe lights inserted *into* slot machines to blind/overload
the hopper ("coin dispenser") and trick it into dispensing more
coins than it should (by interfering with the machine's ability
to *count* actual coins).  Or, pzieoelectric (cigarette) lighters
used to "crash" processors in pay telephones to get free/extended
calls.  Or sitting on the glass top of a pinball machine to prevent
targets from resetting (thereby improving your chance of "earning"
a free game).  etc.

It's a matter of the expense, risk and potential efficacy of a
particular attack vs. the possible reward from that action.

> classes. Realistically, if those are your opponents, I'd give up.
> Whatever you do I suspect you'll loose that battle. Those guys are crafty.

You can never stop someone from simply trying to "annoy" you.
But, if they are getting little else from their actions, they
eventually stop -- especially if they have to be *on* your
property (home, business) to engage in such an attack (i.e.,
you can prosecute them, eventually).

> I'd be happy to see this discussion devolve into a discussion about how
> best to attack a 'hardened' network... Its bound to be interesting.
>
> [1]
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