Yep, you can. That isn't the only variable there though; it needs an active interface, whose name can differ from box to box; I'd have to look through the output of `ifconfig` to definitively yield an interface that was receiving packets.

I would suggest pulling it in; I can look around and try writing a test that tests the tool directly. (I'm thinking something like getting a pcap from http://wiki.wireshark.org/SampleCaptures, and then processing it).