![]() ![]() Use the command + Space bar key combo to bring up the search diaglog box in the upper right top of the screen and type in the word terminal, this will search for the terminal application.If you run OS X 10.6 (Snow Leopard) or above, then you can easily use the command line utility airportd. It is always good to remember that your macbook sniffer needs to be at least as capable as the client you are sniffing (sniffing an 802.11ac smartphone with an 802.11n macbook is not optimal). Wi-Fi diagnostics is the preferred method in the latest macbooks. This document covers OS X 10.6 through the latest version. However, it depends on what versions of OS X you are running, as the commands can vary. Wireless sniffing on the Mac works well, as Mac OS X has built in tools to capture a wireless trace. Wireless Sniffing with a Mac with OS X 10.6 and higher. ![]() The command is: config 802.11 Sniffer Tools This should only be a temporary configuration change. If necessary, the WLC configuration can be changed to only use the slower long guard interval. It misses 20% to 30% of short guard interval packets. Note: The Linksys USB600N does not reliably collect 11n packets with short guard interval. In order not to fill up your hard drive, you want to put an upper limit on the number of files written. Step 7: If you are capturing for a long period of time (hours), then configure your sniffer to cut a new capture file every 30MB or so. To have your timestamps even one second off makes the collation much more difficult. The packet capture needs to be collated with debug captures, and with other wired and/or wireless captures. 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. ![]()
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