ARPD(8) | 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¶
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 |