# Technical Background

(back)

In order to enable libpcap and wireshark to capture frames from an embedded application that connects via a serial RS232 or USB port to the PC, the following setup is needed

     ((o))
       |
       +-[HwPlattform]--SerIf--+--[ieee802154.py]--WsPipe--[libpcap/*shark]
                        (-p)   |                       (-i)
                               |
         [PcapFile]----FileIo--+
                        (-r)

The python script ieee802154.py provides a interconnection between a serial interface `SerIf` or a capture file `PcapFile` (in pcap file format) and a named pipe `WsPipe`, which is used as a live capture interface from wireshark/tshark.

On the MCU the sniffer firmware is installed.

Note:
  The serial interface needs to be sufficient fast in order to transfer all received frames over `SerIf`. The interface has to be able to handle a data rate of 250kbit/s, which is the brutto data rate for the 2.4GHz radio transceivers. Therefore boards like STK541 and grpSTB230 with the parallel USB interfaces (e.g. with FT245 from FTDI Chip Inc.) () are most suitable.

In order to capture packets from a embedded device or a capture file, at first the script ieee802154.py is started. In the next step one of the capture tools, i.e. tshark, dumpcap or wireshark is attached to the socket. The packets that now arrive at the serial interface or read from the capture file are forwarded to the socket and will be processed by the selected tool.

Note:
  Only one capture tool can be connected at a time to ieee802154.py.