As DragonFly's USB subsystem is heavily based on FreeBSD's we can simply enable the USB capture code for FreeBSD in net/libpcap as with attached patch.
USB packets can then be captured with e.g. /usr/local/sbin/tcpdump -i usbus1 -w /tmp/usb.pkts.
patch-pcap-bpf.c.txt
As DragonFly's USB subsystem is heavily based on FreeBSD's we can simply enable the USB capture code for FreeBSD in net/libpcap as with attached patch. USB packets can then be captured with e.g.
/usr/local/sbin/tcpdump -i usbus1 -w /tmp/usb.pkts
. patch-pcap-bpf.c.txt