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D-Link DWL-120 Hacking/Probing

D-Link DWL-120 Hacking/Probing

I found 3 or 4 of these at a garage sale a few years ago for a few bucks, and I am (surprisingly) just cracking them open now.

On the front, it is marked as D-Link DWL-120 11Mbps Wireless USB Adapter, on the back is FCC ID# MXF-WL280, H/W: B2, F/W: 2.25

On the bottom of the PCB, we have the following chips:

  • Atmel AT76C503AWireless LAN MAC Unit with ARM7TDMI RISC Processor
  • Atmel AT25040N4K (512 x 8) SPI Serial EEPROM
  • tmTECH T14L1024N128 x 9 High-Speed CMOS Static RAM
  • Intersil HFA3861BINDirect Sequence Spread Spectrum Baseband Processor

On the top of the PCB (under the RF shield), we have the following chips:

  • Intersil HFA3683AIN2.4GHz RF/IF Converter and Synthesizer
  • Intersil HFA3783INI/Q Modulator/Demodulator and Synthesizer
  • Intersil HFA3983IV2.4GHz Power Amplifier and Detector

I plugged it into my i386-based laptop (My x64 desktop doesn’t have drivers) and got this dmesg:

[   80.592101] usb 1-2: new full speed USB device using uhci_hcd and address 2
[   80.763204] usb 1-2: configuration #1 chosen from 1 choice
[   81.504200] cfg80211: Using static regulatory domain info
[   81.504209] cfg80211: Regulatory domain: US
[   81.504215] 	(start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp)
[   81.504224] 	(2402000 KHz - 2472000 KHz @ 40000 KHz), (600 mBi, 2700 mBm)
[   81.504233] 	(5170000 KHz - 5190000 KHz @ 40000 KHz), (600 mBi, 2300 mBm)
[   81.504241] 	(5190000 KHz - 5210000 KHz @ 40000 KHz), (600 mBi, 2300 mBm)
[   81.504248] 	(5210000 KHz - 5230000 KHz @ 40000 KHz), (600 mBi, 2300 mBm)
[   81.504256] 	(5230000 KHz - 5330000 KHz @ 40000 KHz), (600 mBi, 2300 mBm)
[   81.504264] 	(5735000 KHz - 5835000 KHz @ 40000 KHz), (600 mBi, 3000 mBm)
[   81.504290] cfg80211: Calling CRDA for country: US
[   81.654555] cfg80211: Regulatory domain changed to country: US
[   81.654567] 	(start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp)
[   81.654577] 	(2402000 KHz - 2472000 KHz @ 40000 KHz), (300 mBi, 2700 mBm)
[   81.654585] 	(5170000 KHz - 5250000 KHz @ 40000 KHz), (300 mBi, 1700 mBm)
[   81.654593] 	(5250000 KHz - 5330000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
[   81.654601] 	(5490000 KHz - 5710000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
[   81.654609] 	(5735000 KHz - 5835000 KHz @ 40000 KHz), (300 mBi, 3000 mBm)
[   81.912231] Atmel at76x USB Wireless LAN Driver 0.17 loading
[   81.912307] usb 1-2: firmware: requesting atmel_at76c503-i3861.bin
[   81.965349] usb 1-2: using firmware atmel_at76c503-i3861.bin (version 0.90.0-44)
[   81.967174] at76c50x-usb 1-2:1.0: downloading internal firmware
[   84.329808] usb 1-2: reset full speed USB device using uhci_hcd and address 2
[   84.477154] usb 1-2: device firmware changed
[   84.477265] usbcore: registered new interface driver at76c50x-usb
[   84.492786] usb 1-2: USB disconnect, address 2
[   84.604098] usb 1-2: new full speed USB device using uhci_hcd and address 3
[   84.781393] usb 1-2: configuration #1 chosen from 1 choice
[   84.789161] at76c50x-usb 1-2:1.0: downloading external firmware
[   85.032206] phy0: Selected rate control algorithm 'minstrel'
[   85.034924] phy0: USB 1-2:1.0, MAC 00:05:5d:f1:9d:39, firmware 0.90.0-44
[   85.034935] phy0: regulatory domain 0x00: <unknown>
[   85.383777] udev: renamed network interface wlan0 to wlan1
[   89.584738] ADDRCONF(NETDEV_UP): wlan1: link is not ready
WIP: Cantenna

WIP: Cantenna

This shows step by step how I made a Cantenna. This is a simplified tl;dr version of “How to build a tin can waveguide antenna” by Gregory Rehm.

Materials:

  • 1x Can, washed (hapi HOT Wasabi Peas [450g])
  • 1x N-type, Female Chassis-mount connector (Digikey# 367-1081-ND)
  • 1x Piece of copper wire
  • 4x Nuts & bolts

Prep:

  1. Measure diameter of the can -> 3.9″
  2. Calculate wavelength using waveguide calculator found here.
  3. Mark a point 1/4 Wavelength up from the bottom (closed) side of the can.
  4. Measure the hole to be cut (diameter of part of the connector that will be going inside the can) -> 0.43″
  5. Drill marked point to measured diameter (0.43″)
  6. Dry-fit the connector, and mark holes for the screws or nuts/bolts (if any)
  7. Drill marked points to the diameter of your connector’s holes (if any)
  8. Cut a piece of copper wire so that when it is in the copper sleeve on the connector, the total length of the copper sleeve and piece of copper is exactly 1.21″ (or as close as you can humanly get to it), and solder it in place.
  9. Mount the connector in the hole in the can and secure it with screws or nuts/bolts (if any). Make sure to mount the heads of the screws or bolts inside the can to reduce antenna obstruction.