Obtained from: An old BPF release packaged with the tcpdump-2.0 source code.

"Yes Virginia, there is a rarpd."

(Before anyone asks, this *not* the rarpd from NetBSD. It did come from
the same place as theirs, however.)

This is a port of the rarpd program included with the tcpdump-2.0
source code (which I finally unearthed after scrounging around
some of the darker corners of the Internet). It's as close to the
original as I could keep it except for the following changes:

- The original program was based on an older version of the Berkeley
  Packet Filter which used different filter programming instructions.
  Fortunately, an updated RARP packet filter is available right in the
  BPF man page so this was easy to fix.

- The old code didn't know how to deal with variable length addresses
  in ifreq buffers. This has been fixed.

- Some byte order weirdness had to be fixed. The sanity checks in
  rarp_check() needed some htons()es, and the rarp_reply() function
  needed to properly set the ether_type field in the ethernet header
  to ETHERTYPE_REVARP before transmitting the packet, otherwise
  the bytes in ether_type would wind up reversed. It is important to note
  that using htons(ETHERTYPE_REVARP) will not work. This is odd, because
  the NetBSD rarpd uses htons(ETHERTYPE_REVARP). (Praise be to tcpdump:
  I would never have been able to track this silliness down without it.)

- The update_arptab() function has been castrated. It depends on
  SIOCSARP which has been deprecated in 4.4BSD. The NetBSD people
  don't seem to be using this function either. It wouldn't be too
  hard to replace this with equivalent code from arp.c, but it
  might not be necessary.

- I put together an ether_ntohost() support function that allows
  both local (/etc/ethers) and NIS lookups. This stuff should go
  in libc at some point, but nothing else seems to need it for now,
  so it can wait a while.

As you may have guessed, you need to have the Berkeley Packet Filter in
your kernel in order to use this program. The good news is that together
with the recently added bootparamd, you can use finally use a FreeBSD
box to boot Sun boxes over the network. (This was my whole motivation
for getting this stuff to work: I have this one subnet that has a whole
bunch of Sun3 X-terminals on it with only two Sun4 workstations, both
of which are locked in peoples' offices. If those two machines crash
(and they do every so often) then none of the X-terms will boot. Now I
can use a spare PC that I have as a boot server. :)

1 files changed, 92 insertions, 0 deletions

diff --git a/usr.sbin/rarpd/rarpd.8 b/usr.sbin/rarpd/rarpd.8
new file mode 100644
index 0000000..c19bc30
--- /dev/null
+++ b/usr.sbin/rarpd/rarpd.8
@@ -0,0 +1,92 @@
+.\" @(#) $Header: tcpdump.1,v 1.30 90/10/11 19:35:03 mccanne Exp $ (LBL)
+.\"
+.\" Copyright (c) 1988-1990 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that: (1) source code distributions
+.\" retain the above copyright notice and this paragraph in its entirety, (2)
+.\" distributions including binary code include the above copyright notice and
+.\" this paragraph in its entirety in the documentation or other materials
+.\" provided with the distribution, and (3) all advertising materials mentioning
+.\" features or use of this software display the following acknowledgement:
+.\" ``This product includes software developed by the University of California,
+.\" Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
+.\" the University nor the names of its contributors may be used to endorse
+.\" or promote products derived from this software without specific prior
+.\" written permission.
+.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
+.\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
+.\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+.\"
+.TH RARPD 8 "26 Oct 1990"
+.SH NAME
+rarpd \- Reverse ARP Daemon
+.SH SYNOPSIS
+.na
+.B rarpd 
+[
+.B \-af
+]
+[
+.I interface
+]
+.br
+.ad
+.SH DESCRIPTION
+.LP
+.I Rarpd
+services Reverse ARP requests on the Ethernet connected to
+.I interface.
+Upon receiving a request, 
+.Irarpd
+maps the target hardware address to an IP address via its name, which 
+must be present in both the
+.I ethers(5)
+and 
+.I hosts(5)
+databases.
+If a host does not exist in both databses, the translation cannot
+proceed and a reply will not be sent.
+
+Additionally, a request is honored only if the server
+(i.e., the host that rarpd is running on)
+can "boot" the target; that is, if the directory 
+/tftpboot/\fIipaddr\fP
+exists, where \fIipaddr\fP is the target IP address.
+
+In normal operation, 
+.I rarpd
+forks a copy of itself and runs in
+the background.  Anomalies and errors are reported via 
+.I syslog(3).
+
+.SH OPTIONS
+.LP
+.TP
+.B \-a
+Listen on all the Ethernets attached to the system.
+If `-a' is omitted, an interface must be specified.
+.TP
+.B \-f
+Run in the foreground.
+
+.SH FILES
+/etc/ethers
+.br
+/etc/hosts
+.br
+/tftpboot
+.SH SEE ALSO
+bpf(4)
+.br
+RFC 903: Finlayson, R.; Mann, T.; Mogul, J.C.; Theimer, M.  Reverse Address 
+Resolution Protocol.  1984 June; 4 p.
+.SH AUTHORS
+Craig Leres (leres@helios.ee.lbl.gov) and
+Steven McCanne (mccanne@helios.ee.lbl.gov).
+Lawrence Berkeley Laboratory, University of California, Berkeley, CA.
+.SH BUGS
+You must have the Berkeley Packet Filter configured into your kernel
+in order to use this program. This isn't really a bug, but it isn't
+exactly a feature either.