E-terrorism, Bark or Bite?

packeteer writes: "Huge multi-part article on CNET news about electronic terrorism. The article has some interesting scenarios about posible types of attacks. It also has some good info about whats being done to prevent attacks as well as some info about media-hype that's put on 'hackers'. Good read."

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Traffic signal conflict monitors

[Animats]

Traffic signals in the US have a "conflict monitor", a hardwired device that is connected to all the green light power circuits. It's a physically separate box inside the signal controller. If it detects an invalid combination, it drops a relay that switches all the lights to blinking red/yellow. The matrix that indicates which lights conflict is hard-wired on a plug-in board with a matrix of diodes (typically 120 of them) representing each possible conflict. Programming the board is done by physically clipping out diodes.

Remote reset after a conflict detection is possible for some units, but takes 6-10 seconds, during which period all lights are in blinking red/yellow.

There's an NEMA spec for this, and this functionality is required.

Unfortunately, there's a trend towards putting more functionality in the conflict monitor so it can diagnose and report other problems, then giving it some communications capability. This is a concern. But conflict monitors are, intentionally, much dumber than the main controller, which is a full-fledged computer typically running OS-9.