NAME

       rarpd - Reverse Address Resolution Protocol (RARP) daemon

SYNOPSIS

       rarpd [-aAvode] [-b bootdir] [interface]

DESCRIPTION

       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 rarpd responds with their IP  address
       if  it  finds  it in the ethers database (either /etc/ethers file or NIS+ lookup) and using DNS lookup if
       the ethers database contains a hostname and not an IP address.   In  addition,  /etc/hosts  will  provide
       further means of pairing an IP address to a hostname, in the standard fashion.

       By  default  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,
       192.168.0.122 would correspond to an image named like C0A8007A.SUN.

       The  optional  argument  interface  restricts  the  daemon  instance to access only the indicated network
       interface. Only a single name is possible.

OPTIONS

       -a     Do not bind to a single interface, but listen at all configured interfaces.

       -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.

       -v     Tell the user what is going on by being verbose.

       -d     Debugging mode. Do not detach from the tty. This also implies verbose mode.

       -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 rarpd refrain from responding to requests for this particular address.

       -o     Accept offlink packages on the active interfaces.

       -b bootdir
              Access  bootdir  instead  of  the  default /tftpboot as the TFTP boot directory for bootable image
              checks.

OBSOLETES

       This daemon rarpd obsoletes kernel rarp daemon present in Linux kernels up to 2.2 which was controlled by
       the rarp(8) command.

SIGNALS

       SIGHUP Renew the internal address list, which records IPv4 addresses available  at  each  active  network
              interface.  The  restriction  set by the command line argument interface is still in effect, if in
              use.

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 -A 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.

FILES

       /etc/ethers
              Text data base of ethernet to host pairs.

       /etc/hosts
              Text lookup table of host names.

       /etc/nsswitch.conf
              Name resolver configuration.

       /tftpboot
              Default boot directory.

       /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 HEXADDR.  Optionally, the name  may  be
              extended with an arbitrary suffix.

SEE ALSO

       ethers(5), hosts(5), nsswitch.conf(5)

AUTHORS

       Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
       Jakub Jelinek, <jakub@redhat.com>

rarpd                                             7 April 2000                                           RARP(8)