A lot of people ask me for advice about wifi hacking. This is my attempt at a "portal" page, a page that briefly introduces the most important information you need, with links to deeper reading material elsewhere.

• radios (cards)
  • unless you got lucky, you'll probably have to buy another card, since most cards don't have the proper drivers
  • aircrack's list is comprehensive
  • Having an antenna connector (not just an internal antenna) is a must. A good radio must be paired with a good antenna to be really effective, and you want to upgrade to a directional antenna for point-to-point communication.
    • Yes, it's possible to hack your own connector, but it's not easy.
  • I own the Alfa AWUS036H, and really like it. USB means the same card will work on laptops+desktops.
  • The Ubiquiti Bullet2 is both sexy and cheap, it's by far the best outdoor solution. (img1, img2, img3, img4) (video1, video2, video3)
    • seriously, it can be had for $40 (an astonishing price for a weatherproofed radio), it uses the Atheros chipset, and can run OpenWRT and other third-party Linux distros
• antennas
  • CHEAP add-ons that don't require you to have detachable antennas
    • cardboard + foil
    • asian cookware
  • cantenna — DO NOT use a Pringles can, they are too small for this band. Use a 2.87" - 3.66" (72-93mm) diameter soup can instead. Use this calculator and this kit.
  • a 24dBi parabolic antenna is the best antenna money can buy
• software
  • Linux only, never Windows (unless you can pay $100s for commercial drivers)
  • BackTrack is a great distro because it contains most third-party wifi driver patches
    • you really only need to do the cracking phase once in a while; after you get the password, you can go back to your normal distro (or Windows) and use completely standard software
• tricks-n-tips
  • When building your own antenna, you want to make sure that any plastic that you use in front of the antenna is RF-transparent. How do you make sure it is? Put it in the microwave and see if it gets warm!! Home microwaves use a similar frequency, so any microwave-safe plastic dishes should work well.
  • Many building materials (eg. low-E thermal glass, foil-backed insulation) block wifi, so it's important to put your antenna outside.
  • You really want to keep the radio and antenna as close together as possible. At higher frequencies (2.4gHz is pretty high), cable is really lossy; it's best to only use a foot or two of cable. This unfortunately^* means that you really want to put a radio on your roof.
    * see "cost of weatherproofing delicate electronics" above
    * see also "danger of not using proper lightning protection"
  • If you're feeling really ambitious, you also want to mount your antenna as high as possible.