Client fingerprinting, in my opinion, is one of those features that many people don’t think about until they either need it, want it, or it’s broken. It’s not as sexy as other Wi-Fi security related topics such as 802.1X or micro segmentation and it’s certainly not going to prevent a client from operating correctly on the network if it’s not available (or can it?). However, it does help provide insight into your Wi-Fi client base which can be valuable in terms of knowing what device or devices are popular and making sure your Wi-Fi supports them well. Additionally, it is possible to tie access controls to clients by their device type which can affect what they are able to do on the network. With that said, it’s probably worth knowing how client devices are identified from their manufacturer down to the OS version and more importantly, the methods your Wi-Fi vendor uses to identify them. In this post, I’m going to discuss how client fingerprinting is done in general, how RUCKUS does it, and how one method of fingerprinting that we use today is changing due to security concerns.