This process will automatically disconnect the MacBook from any active wireless network and transmission, instead dedicating the MacBook’s wi-fi card to sniff wireless traffic, capture packets and save it to a file.
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Option+Click on the Wi-Fi menu item in the OS X menu bar.
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Choose “Open Wireless Diagnostics” from the list to open the wi-fi utility.
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Ignore the splash screen and pull down the “Window” menu, choose “Sniffer” from the list of options in the Wireless Diagnostics menu.
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Select the Wi-Fi Channel and channel Width to sniff and capture packets for and click “Start”.
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When satisfied with the length of the packet capture, or when sufficient network traffic has been sniffed, click on “Stop” to end the packet trace and to save the captured packet file to the Desktop.
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The captured packet file will appear on the desktop with a .wcap extension and include the time of the packet capture, the name should look something like “2021.05.20_14-30-12-PDT.wcap”. Now this file can be opened in Wireshark or other capture analysis tools.
