Name

rarpd − reverse address resolution protocol (RARP) daemon

Syntax

/usr/etc/rarpd [ interface ] [ −v ] [ −n ] [ −f filename ]

Description

The rarpd daemon maps the Ethernet address of a machine to the machine’s Internet Protocol (IP) address.

When rarpd is invoked, it reads the /etc/ethers file (by default) and waits to process a RARP request. The /etc/ethers file is checked every ten minutes for any changes.  If the file has been modified, rarpd reads it again. You can disable this feature with the −n option. You can force a scan of the /etc/ethers file by sending the rarpd daemon a SIGHUP signal.  See signal() for more information on SIGHUP.

The format of the /etc/ethers file is described in ethers(.). You can specify a file other than /etc/ethers with the −f option.  The interface is the network interface on which the rarpd daemon should listen. The command netstat −i shows the correct interface or interfaces for your system. The rarpd daemon uses the first interface it finds, if you do not specify an interface.  See the netstat() reference page for more information.

Because the rarpd daemon has been implemented with the Ethernet Packet Filter (see packetfilter(),)), you must configure your kernel with the packet filter option in order for rarpd to function properly. The packet filter detects RARP broadcast packets and passes them to rarpd for processing. The filter priority for rarpd is set to 28.

All messages from the rarpd daemon are directed to syslog.

Options

interfaceSpecifies the system’s network interface. 

−vCauses rarpd to operate in verbose mode. This option logs details of RARP to syslog. The instance of a RARP request and its response are also logged.

−nDisables checking of the ethers() file.  By default, rarpd checks the ethers file once every ten minutes, and, if the file was modified, rarpd rereads the file. If you specify the −n option rarpd scans the /etc/ethers file once at startup time.

−f filenameReads an alternate Ethernet address file. 

Restrictions

The rarpd ignores all ARP requests sent encapsulated within a RARP packet. You should make all ARP request using the arp command.

The machine for which an IP address is being requested must be present in the server’s /etc/hosts file.

Diagnostics

The following message is logged to syslog if the Packet Filter is not configured in your kernel:

Packet Filter is not configured in /vmunix

The following messages are printed to your screen if the Packet Filter is not configured in your kernel:

rarpd: cannot find symbol Pfilt_read in /vmunix
option PACKETFILTER does not appear to be configured in
       your kernel.

Files

/etc/ethers Database that maps Ethernet addresses to hostnames

See Also

ethers(3n), packetfilter(4), ethers(5), hosts(5), arp(8c), ifconfig(8c), syslog(8c)
The Packet Filter: An Efficient Mechanism for User-Level Network Code