The Power to Shoot Yourself in the Foot

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I’m a big fan of the DD-WRT open source firmware for wireless routers. It and the various derivative forks allow you to do all sorts of interesting things with cheap wireless routers. At one point in Shaun’s old place (a normal Chicago-sized apartment) I had built a crazy setup using 4 Linksys WRT-54G routers to bridge his cable modem to a variety of Tivos and game consoles in a variety of rooms. And at PB I used a DD-WRT offshoot meant for coffee shops to build a guest wireless network that covered their spread-out office.

And so when I had the least bit of trouble with my current Dlink DIR-615 cheap-o router, I flashed it with the appropriate version of DD-WRT.

Of course, as Spiderman taught us, with great power comes great responsibility. Today I learned that:

  • Wireless N (the fastest protocol my router will handle) requires WPA2 encryption with the AES algorithm
  • DD-WRT will let you choose N mode AND choose the alternate TKIP algorithm. That means that the router won’t do N anymore, but will drop down to G, but it’ll let you do it and won’t complain. (I don’t know why it was set to this—some experiment I did sometime?)
  • I won’t notice until I’m having trouble connecting to the wireless in the bedroom and try using NetSpot and it reports that my router is only doing G.

It took me a while to track that down as the problem, so I’d thought I’d share.