what are the interfaces (in wireshark) that I should use to analyse RPL packets installed on motes?

Hi! I need to analyse RPL packets. For that I use an application that sniff all packets in the network. I install this application on mote and I use it USB port for sniffing. But I use wireshark I don't find this USB interface to analyse packets. What interface should I use to capture RPL packets exchanged between motes? Is there any configuration that I have to do to be able to capture from the sniffer mote? Thank you!