[Washi]

Can you explain why you need to authenticate NTP?

To prevent spoofing.

[Darth Reardon]

If you’re worried about spoofing, I kind of wonder if you are trying to use the wrong tool for the job. Depending on the environment, iptables (or syncing via hypervisor tools) is probably a much better tool.

But anyway, here’s a easy to follow explanation with examples:

http://www.articlesbase.com/programming-articles/how-to-configure-your-linux-ntp-server-1105782.html

As far as confirming operation, ntpq should (I think, working from memory here). If that’s not enough for you, break it intentionally and test.