AFAICS, there is currently no way to put any of the XBee modules in a "promiscuous" mode, where it justs listens on the network for packets and transmits any packets received through the serial port, regardless of addressing, PAN, or checksum errors. Combined with a small script that translates API packets to the pcap format, this allows capturing (802.15.4) radio traffic using wireshark, which can greatly help in diagnosing network problems.
I've done something similar using a Pinoccio board and my serial-pcap
tool, which has proven its worth already. However, it would be even better if one could just use the XBee modules themselves for this.
I don't know details about the Ember and Freescale platforms used in the XBee modules, but I would expect that this isn't terribly complicated to implement. On the serial side, I think sniffing is meaningless in transparent mode, so only API mode would need to be supported. This would require adding an additional "Promiscuous RX" packet type, that just contains the raw data without any control fields, and a single AT command to start/stop promiscuous mode. All normal RF processing can be suspended when promiscuous mode is enabled.
Any chance this will be included in a future firmware version?