How do I use UTC with NTP? Looking at:

https://support.apple.com/kb/PH9069

How do I set the clock to use UTC with NTP?

(This is in the context of synchronizing the Mac with the Linux server, both should be using UTC and, preferably, connect to the same NTP server.)
OSX has NTP built in, and enabled by default already.

From the Apple menu -> System Preferences -> Date and Time

Make sure that Set Date and Time Automatically is checked. That's NTP. You can pick a default Apple NTP server, or set your own, eg. pick one from here: http://www.pool.ntp.org/zone/north-america

For UTC time zone, click over to the Time Zone tab, and enter "UTC - United Kingdom" as the Closest City.