WifiNigel

Meru access points, like many other controller-based APs, can use DHCP option 43 to acquire the address of the wireless LAN controller that they need to join. In brief, controller-based APs need to find their way back to a controller to obtain their operating code and parameters. Out-of-the-box, they don't know the IP address of the controller they should be talking to. When they are hooked to a wired network, they will request an IP address via DHCP. The DHCP process can also be used to pass them the address of the wireless LAN controller they should be speaking with (in addition to the usual parameters such as IP address, mask, default gateway etc.). DHCP option 43 is used to pass the WLC IP address information to the AP. However,  figuring out the format of the information that should be put in to the option 43 field can be something of a challenge, depending on the DHCP server you are using. I recently had to set up a DHCP server on a Cisco switch to provide IP ad

I've been doing some study for my CWAP  (wireless analysis) exam recently, so I've been spending quite some time staring at Wirehsark traces trying to figure out precisely what all of those 802.11 fields actually mean. One thing I noticed whilst pouring over a few capture files is that some of them seemed to have some additional fields included in the trace, which seem to have nothing to do with fields defined in 802.11 frames at all. They are in a section of the packet decode called 'RadioTap Headers'. I wasn't too sure what they were and why they are available in some captures, whilst in others they were missing. After a little bit of research, I found out a bit more information and thought it might be worth sharing in a quick blog post. In summary, radiotap headers provide additional information that is added to each 802.11 frame when capturing frames with an analysis application. Just to be clear, these are not part of the standard 802.11 frame form

I was recently reading through the most recent edition the finest WiFi text book in the world (in my opinion): the CWNA study guide . I read the previous versions a couple of times when I took my original CWNA exam and subsequent renewals. Looking through the latest book, I've picked up a a few nuggets which I either missed, or weren't included in the previous versions that I read. I had one "light bulb" moment when reading about antenna radiation patterns.  If you've ever looked at datasheets for antennas or access points, you may well have come across diagrams (like those shown below) that show the radiation pattern of an antenna. Fig1 - Antenna Azimuth Chart Fig2 - Antenna Elevation Chart There are generally two types of radiation pattern shown for each antenna: Azimuth (i.e. the RF radiation pattern when viewed from above the antenna) Elevation (i.e. a side-on view of the antenna RF radiation pattern) These are useful to unders