fx sniff

fx sniff captures the packets flowing in-and-out the Fuchsia target device
and displays the packets in a useful view. This is to run on the development
host.

fx sniff will automatically filter out fx-workflow related packets such as ssh,
package server, logs, zxdb, etc., so that the user can focus on the application
of interest. For those who need to debug the fx workflow itself,
the full command under use is also printed; one can easily modify to meet
their own needs.

[Typical usages]
$ fx sniff wlan                    # capture packets over WLAN interface,
                                   # and show their summaries
$ fx sniff --wireshark wlan        # capture packets over WLAN interface,
                                   # and start wireshark GUI for display
$ fx sniff --file myfile wlan      # capture packets and store
                                   # at //out/myfile.pcapng
$ fx sniff -t 10 wlan              # capture for 10 sec
$ fx sniff --help                  # show all command line options