Wednesday, 9 April 2014

Mac OS X "Set date and time automatically"

Just as I've found the time to write up a blog post along comes an appropriate time related subject.

Recently I examined an Apple iMac running Mountain Lion.  I was only given access to an image. This presented a problem because the matter under investigation relied on accurate time stamps and I had no system clock to check. I knew that by default Apple OS X (Snow Leopard through to Mavericks for certain and probably earlier versions) will Set date and time automatically whilst connected to the internet (to allow a connection to a network time server using Network Time Protocol [ntp] ) as shown in Figure 1.

Figure 1

The problem to overcome then was to establish where this setting was stored - I knew it would be in a plist somewhere - isn't everything Mac related stored in a plist?  :-)  So many plists so little time!  A little bit of research and testing allowed me to determine exactly where the setting was stored and as a result share this with you. Figure 2 shows the overrides.plist in the Finder at the path /private/var/db/launchd.db/

Figure 2

This plist is an xml plist so it can be read easily.  Figure 3 shows this plist viewed with the Xcode Property List Editor.

Figure 3

The key we are interested in is the org.ntp.ntpd key.  If the Disabled value is true Set date and time automatically is turned off.

Hope this helps someone.


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