ddnsu is a "small" dynamic dns updating tool. it's intended use is to
perform an update to a particular online dynamic dns service, and to
have a very small file size so it can be used in embedded environments.
to make this useful you need a separate app which checks when the IP
address of an interface has changed. When I say small, the current
dynamically linked glibc binary is about 7.5kB. Compare this to the
dependencies and sheer size of some ddns-updating-clients in perl and
you'll see how ddnsu is useful.

this application was originally based on updatedd-1.5 by Philipp Benner
and dtcl-0.1.2 by Jeff Irvine, though by now lots if not most of the
code has been modified by myself (Peter Willis).
