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.Dd July 19, 1993
.Dt RARPD 8
.Os
.Sh NAME
.Nm rarpd
.Nd reverse ARP daemon
.Sh SYNOPSIS
.Nm
.Op Fl adfsv
.Op Ar interface
.Sh DESCRIPTION
.Nm
services Reverse ARP requests on the Ethernet connected to
.Ar interface .
Upon receiving a request,
.Nm
maps the target hardware address to an IP address via its name, which
must be present in both the
.Xr ethers 5
and
.Xr hosts 5
databases.
If a host does not exist in both databases, the translation cannot
proceed and a reply will not be sent.
.Pp
By default, a request is honored only if the server
(i.e., the host that
.Nm
is running on)
can "boot" the target; that is, a file or directory matching the glob
.Pa /tftpboot/\fIipaddr\fP*
exists, where
.Em ipaddr
is the target IP address in hex.
For example, the IP address 204.216.27.18 will be replied to if any of
.Pa /tftpboot/CCD81B12 ,
.Pa /tftpboot/CCD81B12.SUN3 ,
or
.Pa /tftpboot/CCD81B12-boot
exist.
This requirement can be overridden with the
.Fl s
flag (see below).
.Pp
In normal operation,
.Nm
forks a copy of itself and runs in the background.
Anomalies and errors are reported via
.Xr syslog 3 .
.Pp
The following options are available:
.Bl -tag -width indent
.It Fl a
Listen on all the Ethernets attached to the system.
If
.Fl a
is omitted, an interface must be specified.
.It Fl d
If
.Fl f
is also specified,
.Nm
logs messages to
.Em stdout
and
.Em stderr
instead of via
.Xr syslog 3 .
.It Fl f
Run in the foreground.
.It Fl s
Supply a response to any RARP request for which an ethernet to IP address
mapping exists; do not depend on the existence of
.Pa /tftpboot/\fIipaddr\fP* .
.It Fl v
Enable verbose sysloging.
.El
.Sh FILES
.Bl -tag -width /etc/ethers -compact
.It Pa /etc/ethers
.It Pa /etc/hosts
.It Pa /tftpboot
.El
.Sh SEE ALSO
.Xr bpf 4
.Rs
.%A "Finlayson, R."
.%A "Mann, T."
.%A "Mogul, J.C."
.%A "Theimer, M."
.%T "RFC 903: Reverse Address Resolution Protocol"
.%D "June 1984"
.%O "4 p"
.Re
.Sh AUTHORS
.An -nosplit
.An Craig Leres Aq leres@ee.lbl.gov
and
.An Steven McCanne Aq mccanne@ee.lbl.gov .
Lawrence Berkeley Laboratory, University of California, Berkeley, CA.
.Sh BUGS
.Nm
can depend on the DNS to resolve the name discovered from
.Pa /etc/ethers .
If this name is not in the DNS but is in
.Pa /etc/hosts ,
the DNS lookup can cause a delayed RARP response, so in this situation
it is recommended to configure
.Xr nsswitch.conf 5
to read
.Pa /etc/hosts
first.