File: rarpd.8

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.TH RARP 8 "7 April 2000" "rarpd" "Linux Programmer's Manual"
.SH NAME
rarpd \- Reverse Address Resolution Protocol (RARP) daemon
.SH SYNOPSIS
.B rarpd
.RB [\| \-aAvode \|]
.RB [\| \-b
.IR bootdir \|]
.RI [\| interface \|]
.SH DESCRIPTION
.B Rarpd
is a daemon which responds to RARP requests.
RARP is used by some machines at boot time to discover their IP address.
They provide their Ethernet address and
.B rarpd
responds with their IP address if it finds it in the ethers database
(either
.I /etc/ethers
file or NIS+ lookup) and using DNS lookup if the ethers database
contains a hostname and not an IP address.
In addition, \fI/etc/hosts\fP will provide further means of pairing
an IP address to a hostname, in the standard fashion.
.PP
By default
.B rarpd
also checks if a bootable image, of a name starting with the
IP address in hexadecimal upper-case letters, is present in
the TFTP boot directory before it decides whether to respond
to the RARP request.
The comparison involves exactly the first eight characters,
and ignores any additional character.
A file name shorter than eight characters in length is unsuccessful.
Typically, \fI192.168.0.122\fP would correspond to an image
named like \fIC0A8007A.SUN\fP.
.PP
The optional argument \fIinterface\fR restricts the daemon instance
to access only the indicated network interface. Only a single name
is possible.
.SH OPTIONS
.TP
.B \-a
Do not bind to a single interface, but listen at all
configured interfaces.
.TP
.B \-A
Respond to reverse requests received as ARP-packets,
in addition to those protocol conformant requests
transmitted as RARP-packets.
See the notes for the background.
.TP
.B \-v
Tell the user what is going on by being verbose.
.TP
.B \-d
Debugging mode. Do not detach from the tty. This also
implies verbose mode.
.TP
.B \-e
Skip the check for bootable images in the TFTP boot directory.
In the absence of this switch, even if the Ethernet address
is present in the ethers database, the lack of a bootable image
for the resolved IP will make
.B rarpd
refrain from responding to requests for this particular address.
.TP
.B \-o
Accept offlink packages on the active interfaces.
.TP
.B \-b \fIbootdir\fR
Access
.I bootdir
instead of the default
.I /tftpboot
as the TFTP boot directory for bootable image checks.
.SH OBSOLETES
This daemon
.B rarpd
obsoletes kernel
.B rarp
daemon present in Linux kernels up to 2.2 which was controlled by the
rarp(8) command.
.SH SIGNALS
.TP
.B SIGHUP
Renew the internal address list, which records IPv4 addresses available
at each active network interface. The restriction set by the command
line argument \fIinterface\fR is still in effect, if in use.
.
.SH NOTES
The protocol stipulates that Reverse Requests be broadcast as
RARP packets, using a protocol number different from that in
use by ARP packets.
However, there has been an obsolete practice of transmitting
also Reverse Requests in ARP packets, and some old clients may
still be around that adhere to that practice.
To activate support for such obsolete client hosts,
the switch \fB\-A\fP must be applied.
Observe, however, that only ARP-packaged ARPOP_RREQUEST
messages are added to the servers responsabilities with the
use of this option, and that the replies to these will be
sent as ARP-packaged ARPOP_RREPLY messages.
.
.SH FILES
.TP
.I /etc/ethers
Text data base of ethernet to host pairs.
.
.TP
.I /etc/hosts
Text lookup table of host names.
.
.TP
.I /etc/nsswitch.conf
Name resolver configuration.
.
.TP
.I /tftpboot
Default boot directory.
.
.TP
.I /tftpboot/HEXADDR
Typical name of a boot image.
It is a file or a directory.
The IPv4 address is translated as eight upper-case,
hexadecimal digits in the mandatory part \fBHEXADDR\fP.
Optionally, the name may be extended with an arbitrary suffix.
.
.SH SEE ALSO
ethers(5), hosts(5), nsswitch.conf(5)
.SH AUTHORS
Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
.br
Jakub Jelinek, <jakub@redhat.com>