> I have a related question. I have a little server sitting in a wall > closet. Does anyone have an easy solution (preferably low tech) for > figuring out that the closet door has been opened?
A switch that shutdowns the server, and a passphrase on the startup. Remote logging of the power-ups, using the S.M.A.R.T. power-up count register on the hard-drive as an arbiter (if the adversary wants to access the disk, they have to power it up, even if they take the disk out of the machine and read it in another machine); of course they can unmount the disk's circuitboard and use their own, but they would first have to be aware about that possibility. Now if the system detects dysparity between the number of system boot-ups and the disk power-ups, an alert is raised. (Of course, it can also indicate just a blackout shortly later followed by another blackout, sooner than the PC manages to start up. Solution: UPS.) Can be spiced up by using a wireless remote control, sending an "unlock" signal into the box, then it will allow you in without raising the ceiling. Otherwise each door opening can switch on a REALLY loud alarm siren. Same result can be achieved by using an encrypted remote connection over the network connection. A battery-backed-up computer-powered X-10 wireless camera, with a receiver somewhere nearby. Advantage: will see the one who opened the box. Can be switched on by the door switch, then the VCR recording its image can be controlled by the presence of the carrier wave from the cam. A microcontroller (ie, my favorite PIC16F84, or one of its numerous successors) with a battery backup and an array of sensors (switches, light sensors...) and an EEPROM to which you record the events. Hidden in the closet itself, built either concealeed or tamperproof (or both). Possibly recording the events to a chip like AT24RF08C, so you could read the event RAM remotely without opening the closet. The trick with the marbles someone came up with, and related methods. However, I don't know how to secure it against a careful adversary who knows the trap is waiting, and at the same time make it possible for you to open the box without spilling the marbles. Except if you'd put the X10 minicam (or jsut a plain webcam) into the box and watch the marbles. Encrypt the access, so the adversary can't learn about the position of the black one in advance. Be creative. Keep in mind the adversary can cut both the power and the network connection before accessing the object (burglars with GSM jammers, cutting off wireless outdial systems after cutting the phone line, appeared here already). If your data are high-profile, think about an autodestruction system. Be aware such system can be used against you as a denial-of-service attack. Have luck :)
