The "ip neighbour" commands from the iproute2 package may provide some of
the functionality that arpd provided. I'm unsure if it does, and I don't
know if the iproute package provides this iproute2 functionality.
A quick look at iproute's source didn't reveal any arp named files, but
the "ip neighbour" command might be there. iproute2 seems to have
misc/arpd.c arpd.c, or doc/arpd.sgml.
Drew Daniels