CTS 054: 4 Scary Things Lurking in Your Wi-Fi

In the spirit of Halloween I wanted to go into a theme of scare and fright. While these may not make the hair on your neck stand, I don’t know maybe they do, these issues can lead to managing a scary wireless network. Scary because of end user complaints and because these can be running on newer wireless networks.

Those four scary things are

  1. Low data rate clients
  2. WPA2, even WEP
  3. 2.4 GHz Zombies
  4. Non Wi-Fi Interference

But before we jump into those 4 things, I wanted to update everyone on my journey to CWNE. This weekend I decided to take the CWDP exam. After a little under a month of studying I successfully passed.

The biggest resource I used was the official study guide by Tom Carpenter. It covered all the objectives of the exam. I felt this one was easier for me than the CWNA or CWAP. The topics were straight forward and common sense. This is probably because of my experience coming from designing some wireless networks but it came natural for me.

Now I plan on tackling the CWSP. Probably my weakest area but I look forward to learning from the Sybex book that was released in September 2016. I also plan on doing quite a few labs to get the security topics down.

4 Scary Things Lurking In Your Wi-Fi

Low data rate clients

Low data rate clients take longer to communicate over the air. They slow down devices trying to communicate on faster data rates. This makes it an inefficient wireless network.

An easy solution is to disable lower data rates such as 1, 2, 5.5, 6, and even 9 Mbps.

Keep in mind that this will shrink your cell size. So design properly!

WPA2, even WEP

I’ve seen some networks still utilizing WEP. There’s no use for this anymore. It’s been proven to be insecure and newer devices support much stronger encryption. WPA2 is also now crackable so it’s time to use stronger security.

Both security methods are a management nightmare because a passphrase has to be changed on every device.

The best solution here is to use RADIUS as much as possible. Keep WPA2 only devices on a separate SSID.

2.4 GHz zombies

The IoT band. The land of interference. A place where all single band clients get together. 2.4 GHz is a crowded spectrum.

Move your clients to 5 GHz as much as possible to avoid the congestion seen on 2.4 GHz. To troubleshoot issues on 2.4 spectrum use a protocol and spectrum analyzer.

Non Wi-Fi Interference

This also relates to the previous item. Non Wi-Fi interference causes high retransmissions on the network. This leads to low throughput.

End users characterize this as slow Wi-Fi, unusable, and poor performance.

Start looking into causes of anything over 15% retry rate. You can use tools such as Wireshark or Metageek’s Eye P.A.

Check out this previous episode around Spectrum Analysis while you’re at it.

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About the Author
Rowell, CWNE #210, is a network engineer in Higher-Ed. He enjoys working with wireless networking technologies and loves to share and engage with the community. You can connect with him on Twitter, LinkedIn, and Facebook.

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