There is a replacement for etherfind, but it has changed name;
in fact it's a whole new program. It IS better. To find it,
though, you would have to realize that network snooping is not
really Ethernet-specific. To end the suspense :-), here it is:
% man -k snoop
snoop snoop (1m) - capture network packets and inspect them
It works differently - it has an immediate mode, a
capture-to-disk mode, and a playback-from-disk mode. Read the
man page for details.
The capture file format is described in RFC 1761.