[chrony-users] New system ntp daemon on macOS 10.13

[Bryan Christianson]

I was just looking through macOS 10.13, wondering why ntpd was not running. Apple seem to have got rid of it and are now using something called timed.
I don't know anything at all about it, other than its running (I just enabled it after stopping chronyd) and I think is using the ntpd config files. There is a man page (posted below). It must have been around for a while as it was available in iOS 5.0

I guess its either NOT making any adjtime() calls and is exclusively using ntp_adjtime(), or alternatively, they have deliberately broken adjtime() in the kernel to match what this timed is expecting. Probably the former rather than the latter I would hope.


TIMED(8) BSD System Manager's Manual TIMED(8)

NAME
timed -- time synchronization daemon

SYNOPSIS
timed takes no arguments, and users should not launch it manually.

DESCRIPTION
timed maintains system clock accuracy by synchronizing the clock with reference clocks via
technologies like NTP. Inputs are merged inside of timed, where it calculates uncertainty to
facilitate scheduling proactive time jobs. timed is also aware of power/battery conditions.

FILES
/etc/ntp.conf
NTP server configuration.

/var/db/timed/com.apple.timed.plist
The cached state of timed

/System/Library/LaunchDaemons/com.apple.timed.plist
The timed service's property list file for launchd(8).

SEE ALSO
date(1), settimeofday(2), adjtime(2), gettimeofday(2), launchd(8)

HISTORY
This timed first appeared in Mac OS X 10.13 and iOS 5.0.


Darwin January 26, 2016 Darwin
--
Bryan Christianson
***@whatroute.net

[Parker, Michael D.]

Hmmm....If I recall timed protocol was used prior to NTP protocol becoming
widely adapted.

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-----Original Message-----
From: Bryan Christianson [mailto:***@whatroute.net]
Sent: Tuesday, July 25, 2017 3:38 PM
To: chrony-***@chrony.tuxfamily.org
Subject: -EXT-[chrony-users] New system ntp daemon on macOS 10.13

I was just looking through macOS 10.13, wondering why ntpd was not running.
Apple seem to have got rid of it and are now using something called timed.
I don't know anything at all about it, other than its running (I just
enabled it after stopping chronyd) and I think is using the ntpd config
files. There is a man page (posted below). It must have been around for a
while as it was available in iOS 5.0

I guess its either NOT making any adjtime() calls and is exclusively using
ntp_adjtime(), or alternatively, they have deliberately broken adjtime() in
the kernel to match what this timed is expecting. Probably the former rather
than the latter I would hope.


TIMED(8) BSD System Manager's Manual
TIMED(8)

NAME
timed -- time synchronization daemon

SYNOPSIS
timed takes no arguments, and users should not launch it manually.

DESCRIPTION
timed maintains system clock accuracy by synchronizing the clock with
reference clocks via
technologies like NTP. Inputs are merged inside of timed, where it
calculates uncertainty to
facilitate scheduling proactive time jobs. timed is also aware of
power/battery conditions.

FILES
/etc/ntp.conf
NTP server configuration.

/var/db/timed/com.apple.timed.plist
The cached state of timed

/System/Library/LaunchDaemons/com.apple.timed.plist
The timed service's property list file for launchd(8).

SEE ALSO
date(1), settimeofday(2), adjtime(2), gettimeofday(2), launchd(8)

HISTORY
This timed first appeared in Mac OS X 10.13 and iOS 5.0.


Darwin January 26, 2016
Darwin
--
Bryan Christianson
***@whatroute.net

[Bryan Christianson]

Post by Bryan Christianson
I was just looking through macOS 10.13, wondering why ntpd was not running. Apple seem to have got rid of it and are now using something called timed.
I don't know anything at all about it, other than its running (I just enabled it after stopping chronyd) and I think is using the ntpd config files. There is a man page (posted below). It must have been around for a while as it was available in iOS 5.0
I guess its either NOT making any adjtime() calls and is exclusively using ntp_adjtime(), or alternatively, they have deliberately broken adjtime() in the kernel to match what this timed is expecting. Probably the former rather than the latter I would hope.

I spent some time observing it with tcpdump and hunting through the system logs (a nightmare with Apple's new "improved logging"). It seems to be not much more than an sntp client, making calls to the time server and using settimeofday() to set the clock at 15 minute intervals. Maybe its more sophisticated than that, but its not obvious.


Bryan Christianson
***@whatroute.net