RARPD(8) MidnightBSD System Manager’s Manual RARPD(8)


rarpd — reverse ARP daemon


rarpd −a [−dfsv] [−t directory]
[−dfsv] [−t directory] interface


The rarpd utility services Reverse ARP requests on the Ethernet connected to interface. Upon receiving a request, rarpd maps the target hardware address to an IP address via its name, which must be present in both the ethers(5) and hosts(5) databases. If a host does not exist in both databases, the translation cannot proceed and a reply will not be sent.

By default, a request is honored only if the server (i.e., the host that rarpd is running on) can "boot" the target; that is, a file or directory matching the glob /tftpboot/ipaddr* exists, where ipaddr is the target IP address in hex. For example, the IP address will be replied to if any of /tftpboot/CCD81B12, /tftpboot/CCD81B12.SUN3, or /tftpboot/CCD81B12-boot exist. This requirement can be overridden with the −s flag (see below).

In normal operation, rarpd forks a copy of itself and runs in the background. Anomalies and errors are reported via syslog(3).

The following options are available:


Listen on all the Ethernets attached to the system. If −a is omitted, an interface must be specified.


If −f is also specified, rarpd logs messages to stdout and stderr instead of via syslog(3).


Run in the foreground.


Supply a response to any RARP request for which an ethernet to IP address mapping exists; do not depend on the existence of /tftpboot/ipaddr*.


Supply an alternate tftp root directory to /tftpboot, similar to the −s option of tftpd(8). This permits rarpd to selectively respond to RARP requests, but use an alternate directory for IP checking.


Enable verbose syslogging.



Finlayson, R.


Mann, T. ,
Mogul, J.C. , and
Theimer, M. ,
RFC 903: Reverse Address Resolution Protocol
June 1984 ,
4 p .


Craig Leres 〈leres@ee.lbl.gov〉 and Steven McCanne 〈mccanne@ee.lbl.gov〉. Lawrence Berkeley Laboratory, University of California, Berkeley, CA.


The rarpd utility can depend on the DNS to resolve the name discovered from /etc/ethers. If this name is not in the DNS but is in /etc/hosts, the DNS lookup can cause a delayed RARP response, so in this situation it is recommended to configure nsswitch.conf(5) to read /etc/hosts first.

MidnightBSD 0.3 November 16, 2001 MidnightBSD 0.3