WifiNigel

There is a known issue with Windows clients when it comes to marking applications for QoS over wireless. In short, even if a Windows client application is configured to use DSCP 46 (EF), for example to mark voice traffic, it will translate this over the air to to use a layer 2 UP value of 5, rather than 6. This means that it will end up in the Video WMM queue rather than the Voice queue that we’d like. This has an impact on traffic prioritization over the air and could have a negative impact on our high priority traffic. This has been an issue that people have just “lived with” for quite a while, but I suspect there is a solution to this issue. I’m “putting this out there” for feedback as I can’t find any information about others using this technique. I’d like feedback from my peers to understand if the approach is viable or anyone else has used/tried it Background Generally in my articles, I like to provide plenty of background information about a topic to encourage others to ...

*** Note this article is out of date. Please use the information on this page until I get this artcile updated:  https://github.com/WLAN-Pi/WLANPiShark2 *** One huge advantage that Apple Mac users have over owners of Windows 10 machines is the ability to perform a native 802.11 wireless packet capture direct from their built-in wireless NIC. This is extremely useful for wireless pros who want to take a quick over-the air-capture into Wireshark to analyze traffic for troubleshooting purposes. Windows users don’t have the luxury of this native wireless capture capability. In this article, we take a look at how we can use a WLANPi unit as an adapter to capture traffic over the air, straight into Wireshark on a Windows machine. With the WLANPi being powered from the USB of the laptop, this is a super convenient, portable and powerful capture method that gets Windows users a little closer to the capabilities of their cousins on Apple Macs. Background I’ve always felt really bad...

Wi-Fi networking provides us with 2 bands for the operation of wireless LAN networks: the 2.4Ghz band and the 5GHz band. The 2.4GHz band has a reputation of being something of a “sewer” of a band, due to its limited number of usable channels, the number of Wi-Fi devices already using the band, and the high levels of non-Wi-Fi interference that it experiences. Many wireless LAN professionals will generally advise that you put your “important stuff” on the 5GHz band whenever possible. 5GHz has far more channels available, a corresponding lower number of devices per channel, and generally suffers much lower non-Wi-Fi interference. However, beneath the headline of “2.4Ghz = bad, 5Ghz = good”, there lurks a shadowy figure that can be troublesome if you’re not aware of its potential impact: DFS. Background Wi-Fi networks operate in areas of RF spectrum that require no licence to operate. This is in contrast to many other areas of the radio spectrum that generally require some form of (p...

I recently saw a very interesting post from Gjermund Raaen  about Fast Secure Roaming, where he discusses OKC and 802.11r. This reminded me of some roaming issues I had recently observed with OKC myself, which got me looking up information to refresh my memory on a variety of roaming methods and standards. While looking in to the issue, I came across a classic blog post from Andrew Von Nagy about 802.11 roaming. It provides a superb summary of various roaming and security methods. I've read the post several times in the past, but thought that I would really benefit from a summary of its content to act as a memory jogger, rather than reading through the whole document again. For me, things get a little hazy when I start trying to remember the intricacies of the differences between EAP session resumption, PMK caching, OKC and PMK. To save myself some time for the next time I go through this loop, I put together a summary (Cheatsheet) of the content of the roaming variations ...

For the past few years, I've maintained a white paper on the use of the 5GHz spectrum for Wi-Fi networks here in the UK. As Wi-Fi text books tend to focus on the spectrum available in the USA, I put this document together to clarify how 5GHz spectrum may be used in the UK. Following the release of a Voluntary National Specification document by Ofcom in August 2017 ( VNS 2030/8/3 ), additional channels became available for use in the UK on 5GHz. As we now have additional spectrum, it's time for an update to my white paper to detail the new spectrum that is available. Prior to updating the white paper, I published a summary sheet that shows the new spectrum allocation. This can be obtained obtain from my previous blog article:  UK 5GHz WLAN Spectrum Allocation (August 2017)  (this is definitely one to print off and laminate). I have now completed my updates to the white paper, which I am pleased to share with you now. Note that in addition to adding the new spectrum de...

I've been taking a look at Scapy as I've been learning more about Python. It's a great Python-based tool for capturing, analyzing and creating network packets. There are some great resources to learn more bout Scapy, and even some cheat sheets out there. But, as there were quite a few new concepts (for me) and my own interest is in Scapy for 802.11 related activities, I put together my own Scapy for 802.11 cheat sheet . You can grab a copy from here if it may be useful to you. References : Scapy 802.11 cheat sheet  Scapy docs: https://scapy.readthedocs.io/en/latest/ Building Network Tools With Scapy SANS Scapy Cheat Sheet

To address perceived privacy issues, some wireless clients adopt a randomized MAC address in probe frames when probing  for wireless networks. In this post  I take a quick look at how you might see clients using randomized MAC addresses.  Background When a wireless LAN client needs to find a nearby access point to join a Wi-Fi network, it has two choices: Passive scanning: a client will listen to beacon frames, broadcast by nearby access points, that advertise networks that it makes available. This can be quite a slow process, as a client cycles though channels and waits to hear beacons. Active scanning: a client will cycle through channels and send out probe frames to proactively query nearby APs for a specific wireless network (SSID). This will generally be a faster method of finding networks that the client is configured to join, and may be used by all clients in conjunction with passive scanning. One (unfortunate) side-effect of active scanning is t...