If you only have a single channel sniffer available, then have it sniff the roamed-to channel. Step 5: If you can reproduce the problem when a client roams from one channel to another, then a 2-channel sniff should suffice. Since you can not have enough cards to capture all channels, it is a good practice for the test to operate on not more than 4 channels on your surrounding Access Points. Step 4: If you troubleshoot 5GHz, then the number of channels dramatically increases. USB wireless adapters work best for this type of setup. This involves the use of 3 Wireless adapters on your sniffing device, with each one set to channels 1, 6 and 11. Typically in the 802.11b/g (2.4GHz) environment, a three channel sniffer can be required. This is useful for a site survey or to find 'rogues', but not when you attempt to capture an 802.11 problem.)Īlso, bear in mind that your client device can roam to another AP which is on a different RF channel or Band, so you need to plan accordingly.

Lock your sniffer to the channel of interest - do not use the sniffer's 'scan channels' mode! (With 'scan channels', the sniffer cycles from channel to channel every second or so. Step 3: Understand exactly what 802.11 Channel and Band your client device uses before setting up your capture. You cannot take a good wireless sniffer trace if it is running on the device under test (the client machine you want to get a wireless trace of). Step 2: Use a separate device to act as your wireless sniffer. This allows your sniffing device to capture a good approximation of what your client device hears over the air. Step 1: Since the sniffing device, client device and AP are useng RF generating radios for transmission or reception, it helps to have your wireless sniffer close to your target device (the client machine). You want to capture the raw wireless frames from over the air, as seen by the wireless sniffing device itself. With wireless sniffing, it helps to have an idea of what you want to do. There are a few things to bear in mind to help simplify and speed up this process. This process can be a difficult and time intensive operation. This document describes the process to collect a good wireless sniffer trace in order to analyze and troubleshoot 802.11 behavior.

Wifi packet sniffer