The loopback interface should always be captured, as it includes
the 'ping' commands we use to detect the start of the packet capture.
Change-Id: Ic3aee59dd230141a5d182e9babf8d33d59144aa4
We cannot use "-i all" but must list each interface separately,
which is only supported by dumpcap. We also must write pcapng
files.
Change-Id: Id412af3bb6bcad5e0f2cf40a6dc497d7e4f3d948