When using Wi-Fi spectrum analyzers, it's good to remember an old Russian proverb: Trust, but verify.
Recently, I was doing some work for a company that needs BYOD Wi-Fi at several office spaces in multi-tenant buildings (insert: lame excuse for not blogging more) and we ran into what seemed to be an interference problem.
Why did I think it was an interference problem? I had already completed the following checklist:
1. Cisco AP transmit power set to level 2 or 3 (that's 20 dBm to 17 dBm if you're using 3600/3700/3800 APs)? Check.
2. RRM channels 2, 3, 4, 5, 7, 8, 9 and 10 disabled? Check.
3. Excess 2.4 GHz radios disabled based on a survey done using an iPhone 4s? (What can I say? I'm a big softy for users who over-extend the life of their smartphones. They're the real MVPs of climate change.) Check.
4. OmniPeek captures, done from potential "neighbor" trouble areas, to look for channels occupied by large amounts of Retry frames? (This one has become nec…
Two years ago tomorrow Apple introduced the iPhone 5. It was a big deal. It was a big deal for gadget folks who wanted a bigger iPhone. It was a big deal for wireless LAN folks who wanted users to use smartphones with speedier WiFi.
Now the iPhone 6 has been announced and it appears to be more of the same. Gadgeteers get their bigger iPhone. Wireless folks get their faster speeds. Problem is, the faster wireless speeds likely won't mean anything for high capacity wireless deployments.
The big news about the iPhone 6 is 802.11ac. Yippee! Apple has finally adopted the latest and greatest WiFi standard in a mobile device.
802.11ac has data rates as high as 6.9 Gbps in the standard, but wireless LAN folks know that's not what happens in real life. Real 802.11ac devices top out at a 1.3 Gbps data rate when multiple input-multiple output (MIMO) antenna systems are supported, while non-MIMO devices top out at 433 Mbps.
The iPhone 6 and iPhone 6 Plus are non-MIMO 802.11ac d…
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…