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Why You Should Stop Disabling Low Wi-Fi Rates, Illustrated

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The last Sniff Wi-Fi post; on why Wi-Fi professionals should stop disabling low data rates, was met some resistance.  Be it in the comments or on Twitter, several experienced Wi-Fi folks disagreed.

All arguments in favor of disabling low rates (the ones that were presented to me, at least) were refuted in the text of the Leave, Leave, Leave My Rates Alone blog post.  But text is a less accessible messaging method.  "A picture is worth a thousand words", as the old saying goes.

If pictures will get the message across better, then pictures are what I'll use.  What follows is an illustrated look at why disabling low data rates is a bad idea.

 It's gauche to begin an illustrated work with text, but to understand the problem with disabling low Wi-Fi data rates one must first accept some facts about Wi-Fi devices (smartphones, laptops, etc.):

1. Wi-Fi devices -- not APs -- control associations and roaming.

2. Wi-Fi devices roam based on low received signal strength (RSSI) -- …
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Go To Sleep, Go To Sleep, Go To Sleep Little iPhone

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In some circles, Apple Wi-Fi devices are knows to have problems with lost connections.  iPhones and iPads will unexpectedly miss incoming calls, have delays in receiving push notifications and even be forced to reauthenticate.

There is a solution to Apple devices' connection problems, and as with most "device problems", the fix resides on the infrastructure.  The DTIM setting needs to be increased.  (Apple recommends a setting of 3 or higher.)  Here's why:

Some Apple Wi-Fi connection problems stem from Apple iOS devices' use of 802.11 power management.  To understand what Apple devices are doing with power management, one must first understand how 802.11 power management works.

Let's start with unicast data.  The 802.11 standard allows devices' Wi-Fi radios to enter the Doze state in order to conserve battery life.  Wi-Fi radios in the Doze state are unable to receive data from the AP, so APs buffer all unicast data that has a destination MAC address of a…
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Free Sniffing in Windows! (Kind Of)

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Nine months ago (bad way to start a blog post, I know) I wrote a blog about the future of WiFi sniffing.  In the comments section (perhaps the only worse thing for a blogger to say), someone mentioned a free, Windows-based application called Acrylic WiFi.   I briefly checked out the app and dismissed it as yet another Discovery utility disguised as a something more. 

Then I actually used Acrylic WiFi and...  it works!  It sniffs WiFi frames (sort of) and it does it for free (outside of the cost of an ordinary 802.11 USB adapter)!  This changes everything (kind of)!

 For years, the method for free WiFi sniffing on a Mac has been simple.  Head down to the bottom of this post for a reminder.

Now, we can do similar things in Windows.  It's not quite as simple and it's not totally free, but it works (pretty much).

1. Download and install Acrylic WiFi Free, including Monitor Mode support (and, actually, if you can find an old download of Acrylic v1, then you'll be able to save ca…
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