This is a new port of OpenBSD's native ntpd to other Unix flavours adding
autoconf support and the necessary compatibility layer.  It is based on
portability code from the OpenSSH and LibreSSL portable projects.

OpenNTPD has a web site at http://www.openntpd.org/

The current portable tree can be found at https://github.com/openntpd-portable

Platform Requirements
---------------------
adjtime() and settimeofday() syscalls or equivalent.
either poll() or select().
a working arc4random implementation, OpenSSL or LibreSSL
 (this project shares the same arc4random compatibility code from LibreSSL)

At the time of writing the Portable version is known to build and work on:
OpenBSD (5.6)
Linux (Ubuntu 12.04, 14.04)
FreeBSD (9.x, 10.x)

Still in development / integrating fixes from the original OpenNTPD port
Solaris (10.x, 11.x)
Mac OS X (10.9)

It may work on others, newer and older, but it's still a work in progress.
Reports (success or otherwise) and/or diffs welcome.