[PLUG] Ethernet patch cable alarm...

[Fred James]

Michael C. Robinson wrote:
> On Sat, 2011-02-12 at 21:37 -0800, Larry Brigman wrote:
>   
>> On Sat, Feb 12, 2011 at 9:21 PM, wes <plug at the-wes.com> wrote:
>>     
>>>> But seriously, if I may, what is the need exactly?  Are the cables being
>>>> unplugged?  Who is unplugging them?  Why are they doing that?
>>>>
>>>>
>>>>         
>>> The need in this case, is to protect a content-filtered Internet
>>> connection's filter from being circumvented.
>>>
>>>       
>> A physically locked patch panel cabinet would probably suffice.
>>     
>
> Yes, but that is a very expensive solution.  As far as photographing,
> that isn't necessary.  What I'm after is a device that goes into a
> locked cabinet on one end of the patch cable with an alarm and
> the ability to detect the presence of a foreign computer.
> I suppose the servers could be programmed to beep, but a locked up
> headless device that cuts connectivity and beeps is even better.  
> Yes, super gluing the patch cables in place or putting the servers and
> Internet equipment in a locked cabinet, these are potential answers.
> Thing is, I am leery of the super glue idea where the locked rack 
> route is too expensive at this time.
>
> Out of curiosity, how do I program a Linux server to beep when a patch
> cable is disconnected from it?
>
> I'm surprised there isn't a smart ethernet switch for doing this sort 
> of thing already.
>
> Just to be clear, I have a small locked cabinet.  The problem is, the
> servers are outside that cabinet.  So this exposes the patch cables
> going to these servers to abuse.  The who is not important, suffice 
> it to say that temptation is a difficult issue.  A simple rack by
> the way will not necessarily be closed.
>
> I suppose I can whip together a Linux computer that will fit in the
> cabinet and replace the switch with that machine...  I have an extra 
> P4 processor handy and there is probably enough room in the cabinet
> for a micro atx motherboard...  Another option is to use an extra 
> K6-III I found lying around.
>   
Sounds awfully like you have a "critical piece" located in a "public 
thoroughfare" ... not generally considered a good idea, but perhaps you 
have reason.  I wish you luck on that one.

But to the question of how: this sort of thing is usually based on a 
"heartbeat" detection program, where one computer queries the other(s) 
about its(their) condition or existence, and preforms a desired action 
(or set of actions) as needed.  That would normally be done over a 
private network using a dedicated NIC in each machine (preferably 
without going through a switch/router, but just a direct connection).  
The reason is traffic of course, but also to avoid the potential of some 
one interfering in some way with the signal.
Any Help?
Regards
Fred James

PS: supper glue?  where did that come from?  did I miss something?  I 
mentioned locking the ends, but I guess I missed the suggestion of 
supper glue.  Locking the ends is done by sliding a close fitting tube 
up the cable to butt the NIC, and then locking the tube in place.  Not 
perfect, but it generally keeps honest people honest.  Possibly honest 
people are not the problem, being located in a "public thoroughfare"?