TIL that you can analyze live packets from remote network interfaces in Wireshark with the following command:

ssh $SSH_TARGET "tcpdump -w- -i $REMOTE_INTERFACE" | wireshark -k -i-

It’s essentially three commands glued together in a big pipe.

On the left side of the pipe, we have the following to connect to the machine and capture packets in pcap format:

  • ssh $SSH_TARGET ... means “SSH into the machine and execute the given argument”
  • tcpdump -w- -i $REMOTE_INTERFACE, which is executed in on the remote, works like so:
    • -w selects a file to write to. In this case, -w- means “write to STDOUT”
    • -i $REMOTE_INTERFACE specifies the interface to capture on

On the right side of the pipe, there is wireshark -k -i-.

  • -k means “start capturing immediately, don’t bring up the start menu”
  • -i selects an interface or file to get packets from. In this case, -i- means “capture packets from STDIN”

Related note: Oftentimes, when a flag that usually expects a file gets a -, the program supports reading the data from STDIN, or writing the data to STDOUT, depending on what the flag actually does. If you want to use the file specifically named -, you should provide ./- in that argument (i.e. -w ./-)

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