This directory contains generic network interface device drivers that don't contain any hardware or architecture specific code. The files are: etharp.c Implementes the ARP (Address Resolution Protocol) over Ethernet. The code in this file should be used together with Ethernet device drivers. ethernetif.c An example of how an Ethernet device driver could look. This file can be used as a "skeleton" for developing new Ethernet network device drivers. It uses the etharp.c ARP code. loopif.c An example network interface that shows how a "loopback" interface would work. This is not really intended for actual use, but as a very basic example of how initialization and output functions work. slipif.c A generic implementation of the SLIP (Serial Line IP) protocol. It requires a sio (serial I/O) module to work. tcpdump.c Not a network interface driver, but some code that parses a TCP/IP packet and outputs printfs in an tcpdump-like way. Only used for debugging.