Well here's a explaination for DLPI
Sniffing is listening (with software) to the raw network device for
packets that interest you. When your software sees a packet that fits
certain criteria, it logs it to a file. The most common criteria for an
interesting packet is one that contains words like "login" or
"password."
You will have to obtain or code a sniffer that is capable of working
with the appropriate type of network interface. Popular network
interfaces include NIT (Network Interface Tap), and DLPI (Data Link
Provider Interface), and BPF (Berkeley Packet Filter.)
DLPI supports Ethernet, X.25
LAPB, SDLC, ISDN LAPD, CSMA/CD, FDDI, token ring, token bus, and Bisync
as data-link protocols.
