To allow multiple boot servers on the network rarpd optionally checks for presence Sun-like bootable image in TFTP directory. It should have form Hexadecimal_IP.ARCH, f.e. to load sparc 193.233.7.98 C1E90762.SUN4M is linked to an image appropriate for SUM4M in directory /etc/tftpboot.
This facility is deeply obsoleted by BOOTP and later DHCP protocols. However, some clients really still need this to boot.
-a
-A
-v
-d
-e
-b bootdir
rarpd was written by Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>.
rarpd requires CAP_NET_RAW capability to listen and send RARP and ARP packets. It also needs CAP_NET_ADMIN to give to kernel hint for ARP resolution; this is not strictly required, but some (most of, to be more exact) clients are so badly broken that are not able to answer ARP before they are finally booted. This is not wonderful taking into account that clients using RARPD in 2002 are all unsupported relic creatures of 90's and even earlier.
rarpd is part of iputils package.