Ethernet Wiring Through Hostile Territory?

GoogleDidntFindIt asks: "I need to connect a terminal to a server which contains very sensitive information. Unfortunately, the terminal is about 200 feet away from the server. The server (which even includes a 'self destruct' device) and terminal are both in highly secure areas of the building, but the wiring will be in uncontrolled areas. What should I do to keep people from tapping or monitoring the wire?" Is there any way a conduit can be wired with an alarm which goes off when it's integrity has been violated?

"Heres a basic description of my situation:

• A new wire/fiber/cable/whatever will be run and I can use any sort of conduit I want.
• A potential attacker may have several days of undetected access to parts of the wire/conduit and may have sophisticated fiber-optic tapping equipment (which can tap a fiber without cutting it).
• I can physically inspect the conduit/cable/wire once a month.
• Ideally, the system would also notify me of a majority of successful attacks (or, even better, disconnect the line).

I'm aware of IPSEC and other encryption systems, but they aren't suitable for this project - I'm looking for systems which address physical security and protect against traffic analysis."

Comments

Expensive Specs

[clark625]

Okay, my $0.02 will likely cost you a large amount of money; but hey... if the data's so important to require self-destruct devices then I can understand that money isn't the biggest concern. Perhaps some of my ideas will prove useful.

Some of the previous articles mention using vacuum or pressure. This isn't a bad idea; though it could potentially be defeated by extremely carefully poking a small hole (about 5 microns in diameter) and then getting a pressure monitor on there. It may take hours for the gauge to read anything of use; but supposedly attackers may have that long. The hole itself would just look like a very small leak on 200 foot of pipe--and so you would believe that it's not an attacker.

Instead, you really should use a multi-layered configuration. Start with a fiber--they are a pain to tap without splicing; and I'll assume you could monitor each end and check for signal degradation that would be indicative of a splice. Then, the fiber should be insulated already, so jacket it in copper or aluminum sheeting (like grounded CAT5) with insulation on top of that. To top off the internal layer, send this "wire" down the smallest metal tube you can; with Great Stuff or other spray-in insulator filling the gap. Note that the fiber et al should be running nearly down the center of this conduit.

That's the first layer. Outside of that, fit the conduit inside another one (again, metal)--this one should be have a good vacuum on it. 10e-3 torr is easy to reach with a roughing pump, so you shouldn't have any trouble getting there. And then one more pipe outside of that. The final pipe should have a high pressure on it, 75 or 100 psi can be reached by a common air compressor. So this gives a total of three metal conduits to go through before reaching the fiber. Obviously, monitor the pressure from both ends--and those numbers should match up (with some error).

Yes, I realize this seems like over-kill. But, with this set up you can do some really cool things to check for intrusion. First, one can put different voltages across each of the 4 metal layers (fiber jacket included). If any of those are the same, you've got an attacker. You also can connect two layers on one end and gauge the resistance from the other. If this number doesn't match what it was yesterday, then there is an attacker. My personal favorite, though, is checking the capacitance between the different layers. If someone somehow figures out how to cut through the pressure and vacuum jacketting, the resistance test might be able to catch it. If you check the capacitance, there's almost no way they can not be detected. If this were me, I would configure both sides to randomly check different combinations from my list.

Finally, you likely will have a few seconds from when an attacker is detected and when he/she could be possibly be listening. This means that you can fully trust the computer on the other end even just after an intruder detection. Use this time for "Oh my God! Cut the line! Shut up and don't talk again!!!" as well as any other last-second transactions you need.

Re:Conduit under pressure.

[bribecka]

True, under a lot of pressure, but it seems the media has totally forgotten about him. Luckily he probably won't run for reelection.

Oh, Conduit. I have nothing to say about that.