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>