WLAN Frame Capture

Here are a few articles I've put together that fall under the common subject area of frame capture in wireless LANs, I'm not a huge expert in this area, but I like to be able to find my notes easily for the times when I do have to roll my sleeves up :)

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The 5GHz “Problem” For Wi-Fi Networks: DFS

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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 (paid-…
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Microsoft NPS as a RADIUS Server for WiFi Networks: Dynamic VLAN Assignment

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The Microsoft Network Policy Server (NPS) is often used as a RADIUS server for WiFi networks. It can provide authentication and authorization services for users on a wireless network.
In this article we take a look at how users can be dynamically assigned to a VLAN that suits their account privileges, using RADIUS attributes passed back from NPS to the RADIUS client (usually a wireless LAN controller or access point).
This method of assigning a user to a particular VLAN based on their login credentials is also known as Role Based Access Control (RBAC). 

As wireless networks have grown to provide more and more services to organisations, the practice of creating a new SSID for each new service required has fallen out of favour, as each SSID adds more overhead to the RF medium, reducing the available bandwidth for all wireless services. 
Best practice in terms of the number of SSIDs you should have available from your wireless network is generally accepted to be around 4 or 5 SSIDs as a maxi…
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Microsoft NPS as a RADIUS Server for WiFi Networks: Self Signed Certificate

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The Microsoft Network Policy Server (NPS) is often used as a RADIUS server for WiFi networks. It can provide authentication and authorization services for users on a wireless network.
Generally, NPS is used with various EAP methods (e.g. PEAP, EAP-TLS) that require a certificate to be presented by the NPS server to the client as part of the authentication exchange. The certificate proves the identity of NPS (the RADIUS authentication server)  to the client and is used to derive keys to build a TLS tunnel for the secure exchange of credential information.
Most of the time, a Microsoft PKI infrastructure is used to issue a certificate to the NPS server, which is a relatively straightfoward process that is well documented in official Microsoft documentation.
However, there may be times when you want to fire up a version of NPS (perhaps in a lab or POC environment) and just put on your own self-signed certificate, instead of having the additional overhead of getting CA servers etc. going.
Fin…
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