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Thu, 29 Sep 2011

Amazon Kindle wireless bug - and a bugfix

I recently bought a Kindle e-book reader (I'll post a full review later after I've had another week or so of using it) and first impressions are pretty good. Not great, but pretty good.

There was, however, one big problem. It couldn't connect to my wireless network, whose base-station is a Mac Mini running OS X. I talked to a nice lady in Amazon's customer support department, but after getting me to send my Kindle's logs, and having Amazon's engineers look at them, the best she could say was "your router isn't configured properly".

I'm afraid it is configured properly, and everything else - my phone, my iPad, my Linux laptop, my Mac laptop - can talk to it just fine. The only thing that can't is my Kindle.

This is because of a bug in the Kindle's DHCP client. In DHCPDISCOVER messages, the 'secs' field is meant to be set to the number of seconds since the DHCP process started. Many DHCP servers, including (in my case) Apple servers are configured by default to ignore such messages if 'secs' is set to zero, as this indicates a client that isn't fully running yet so any reply may not be noticed. A compliant client will retry if it gets no response, and after a few seconds of retrying 'secs' will be above whatever the server's threshold is, and everything will work. It seems that the Kindle always puts a 0 in that field, in violation of the standard.

To work around it on your Mac, do the following, in this order. I assume Mac OS X 10.6, it may be a bit different in others:

  1. open System Preferences
  2. open "Sharing"
  3. turn off "Internet Sharing"
  4. open Terminal.app
  5. type "sudo defaults write /etc/bootpd reply_threshold_seconds -int 0"
  6. if that asks for your password, enter it
  7. turn "Internet Sharing" back on
  8. sorted

I have emailed the nice lady at Amazon and told her that I have a solution, and that Amazon can have the solution in exchange for a 20 quid gift voucher. Seems only fair, given that people have been complaining on Kindle-ish forums about not being able to use Apple base stations ever since the Kindle was launched. I'm really surprised that Amazon haven't figured it out.

Posted at 19:21 by David Cantrell
keywords: amazon | geeky | kindle
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