debian man page for farpd

ARPD(8) 						    BSD System Manager's Manual 						   ARPD(8)

NAME
     farpd -- ARP reply daemon

SYNOPSIS
     farpd [-d] [-i interface] [net ...]

DESCRIPTION
     farpd replies to any ARP request for an IP address matching the specified destination net with the hardware MAC address of the specified
     interface, but only after determining if another host already claims it.

     Any IP address claimed by farpd is eventually forgotten after a period of inactivity or after a hard timeout, and is relinquished if the real
     owner shows up.

     This enables a single host to claim all unassigned addresses on a LAN for network monitoring or simulation.

     farpd exits on an interrupt or termination signal.

     Note: The program name farpd has been changed in Debian GNU/Linux from the original name (arpd) to avoid name clash with other ARP daemons.

     The options are as follows:

     -d      Do not daemonize, and enable verbose debugging messages.

     -i interface
	     Listen on interface.  If unspecified, farpd searches the system interface list for the lowest numbered, configured ``up'' interface
	     (excluding loopback).

     net     The IP address or network (specified in CIDR notation) or IP address ranges to claim (e.g. ``10.0.0.3'', ``10.0.0.0/16'' or
	     ``10.0.0.5-10.0.0.15''). If unspecified, farpd will attempt to claim any IP address it sees an ARP request for.  Mutiple addresses
	     may be specified.

FILES
     /var/run/farpd.pid

SEE ALSO
     pcapd(8), synackd(8)

BUGS
     farpd will respond too slowly to ARP requests for some applications. In order to ensure that it does not claim existing IP addresses it will
     send two ARP request and wait for a reply. This slowness affects the nmap network scanning tool, and possibly others, which uses by default
     ARP when scanning local networks. The answers from farpd will come after the tool has timeout waiting for the ARP replies and, consequently,
     IP addresses claimed by farpd will not be discovered.

     Additionally, farpd sends the ARP replies to the broadcast address of the network and not to the host that send the ARP request. Some systems
     and applications (notably nmap) will not handled these requests and expect directed ARP replies (i.e. targeted specifically to the host that
     sent the request and not to the network)

AUTHORS
     Dug Song <dugsong@monkey.org>, Niels Provos <provos@citi.umich.edu>

								  August 4, 2001