I wasn’t able to see David Maynor’s “You are the Trojan” (pdf) talk at Toorcon, but it’s a really interesting subject. With such a large emphasis being placed on tightening perimeter security with firewalls and IDS systems how do attacks keep getting through? The user: bringing laptops on site, connecting home systems through a VPN, or just sacrificing security for speed.

Peripherals can also be a major threat. USB and other computer components use Direct Memory Access (DMA) to bypass the processor. This allows for high performance data transfers. The CPU is completely oblivious to the DMA activity. There is a lot of trust involved in this situation. Here’s how this could be exploited: Like a diligent individual you’ve locked you Windows session. Someone walks in with their hacked USB key and plugs it into your computer. The USB key uses its DMA to kill the process locking your session. Voila! your terminal is now wide open and all they had to do was plug in their USB key, PSP, iPod

Backlights are one of the most common failure points on LCD panels. Even though they usually say “no serviceable parts” on the back you might still be able to fix your monitor. Jared Bouck details the removal of the dead cold cathode and replacing it with a new tube and inverter. Not quite as dangerous as opening a CRT, but you still need to be careful with the mercury vapor filled tubes.

[thanks Tom]

Continue reading “LCD Backlight Replacement” →

Yes, it is possible to get sound output from a serial port. Sure, it sounds terrible, but what did you expect. [markrages] ttyplay program first resamples the WAV file to the baud rate of the serial port. It then uses Sigma-Delta modulation to encode the analog signal into a binary bitstream. You should really try this out. The picture above is from when I was testing it out since it only took a minute to grab the parts and a second to compile. Mark says audio quality could be improved by using a higher baudrate. There is a lot of noise though. Somebody want to put together a simple RC filter/amplifier; I can actually think of a project this might be useful for. Read more about ttyplay here.

Continue reading “Audio Output From A Serial Port” →

Most people don’t use their floppy drive anymore so you might as well make a car out of it, right? If you short two sets of pins in the drive connector, the motor will spin freely when 5V is applied. This motor is used to drive the rear axle. The front wheel is steered using the read/write head’s stepper motor. An NE555 timer is used to pulse the motor when the steering buttons are pushed. This design is really simple and has a tethered control, but it is a good starting point if you want to try something else.

[thanks Boff]

Continue reading “Floppy Drive RC Car” →

If you understand that alphabet soup title you’re in for a treat. Igor Cesko’s original project was constructing an IR interface for his computer so he could control it remotely. He built a simple serial dongle for this task because he didn’t want to use a microcontroller for decoding the IR. USB is becoming far more common than serial interfaces so Igor decided to try programming a microcontroller for USB communication. His controller works for his IR project, but it should be easy to use for any other project you want a USB interface on. His most recent project was teaching an AVR to do UDP. Using his IR -> UDP device and a crossover cable he can place the receiver farther away from the computer. It requires a full duplex connection and has been tested connected directly to a NIC. It’s unknown whether it will function properly connected to a router.

[thanks johannes]

Continue reading “USB And UDP Using An AVR” →

[Roo] seems to think we’ve been neglecting the NSLU2 or “slug”. It’s true we have spent a lot of time fawning over the Linksys WRT54G instead. The slug is definitely worthy of attention though. It is a small network appliance with two USB ports that you are supposed to attach disk drives to for simple network storage. Add a little custom firmware and you’re free to use the USB ports for whatever you want.

The XScale processor in the slug comes underclocked from the factory. Following the instructions on the NSLU2-Linux wiki you can pop one resistor off of the circuit board to restore the full 266Mhz. Benchmarks, temperature, and power consumption after the change are covered.

Continue reading “Overclocking A Linksys NSLU2” →