[G4] Setting the computer's clock

[Steve Goldstein]

They get their time from their [restricted access?]  Stratum Two NTP [Network Time Protocol] server:  time.apple.com:

Start: 7/20/05    2:33:42 PM 
;; Query: time.apple.com ,type = ANY , class = ANY

;; ANSWERS:
time.apple.com	445	IN	A	17.254.0.31
time.apple.com	445	IN	A	17.254.0.26
time.apple.com	445	IN	A	17.254.0.27
time.apple.com	445	IN	A	17.254.0.28

;; AUTHORITY RECORDS:
apple.com	398304	IN	NS	nserver.apple.com
apple.com	398304	IN	NS	nserver2.apple.com
apple.com	398304	IN	NS	nserver3.apple.com
apple.com	398304	IN	NS	nserver4.apple.com
apple.com	398304	IN	NS	nserver.asia.apple.com
apple.com	398304	IN	NS	nserver.euro.apple.com

;; ADDITIONAL RECORDS:
nserver.asia.apple.com	167012	IN	A	203.120.14.5
nserver.euro.apple.com	61878	IN	A	17.72.133.64
nserver.apple.com	407523	IN	A	17.254.0.50

See: http://ntp.isc.org/bin/view/Main/WebHome

Note also: http://ntp.isc.org/bin/view/Support/KnownOsIssues#Section_9.2.4.

9.2.4. MacOS X
The MacOS X method of enabling ntpd is to go to the Apple menu option System Preferences..., then into the Date & Time sheet, then go to the Date & Time sub-panel, and click on the radio button labeled Set Date & Time automatically, which allows you to select a time server to use from a drop-down, or you can fill in the name of your own preferred time server.
Note that every time you exit this preference sheet, the system will re-write your /etc/ntp.conf based on the information you have provided.
	*	Even if you have provided your own /etc/ntp.conf, there is no way to prevent the system from re-writing it based on the content of this field.
	*	Even if you don't make any changes to this preference, just by going into this sub-panel and exiting back out, MacOS X will re-write your /etc/ntp.conf.
Unfortunately, when MacOS X creates the /etc/ntp.conf file, it will do nasty things like appending "minpoll 12 maxpoll 17" to every single line, including those lines which do not have a "server" directive.
	*	Worse, any line that had more than two arguments will get the rest truncated and replaced by "minpoll 12 maxpoll 17".
	*	All lines will get the directive "server" prepended to them, even if they weren't originally server directives.
Here's a sample input /etc/ntp.conf file:
         tos minclock 4 minsane 4
         server time.euro.apple.com iburst
         server de.pool.ntp.org iburst
         server fr.pool.ntp.org iburst
         server nl.pool.ntp.org iburst
         server uk.pool.ntp.org iburst
         server 0.europe.pool.ntp.org iburst
         server 1.europe.pool.ntp.org iburst
         server 2.europe.pool.ntp.org iburst
         server 127.127.1.0              # Local clock
         fudge 127.127.1.0 stratum 14    # Undisciplined
         statsdir /var/ntp/ntpstats
         filegen peerstats file peerstats type day enable
         filegen loopstats file loopstats type day enable
         filegen clockstats file clockstats type day enable
Here's what MacOS X will munge this into:
         server tos minpoll 12 maxpoll 17
         server time.euro.apple.com minpoll 12 maxpoll 17
         server de.pool.ntp.org minpoll 12 maxpoll 17
         server fr.pool.ntp.org minpoll 12 maxpoll 17
         server nl.pool.ntp.org minpoll 12 maxpoll 17
         server uk.pool.ntp.org minpoll 12 maxpoll 17
         server 0.europe.pool.ntp.org minpoll 12 maxpoll 17
         server 1.europe.pool.ntp.org minpoll 12 maxpoll 17
         server 2.europe.pool.ntp.org minpoll 12 maxpoll 17
         server 127.127.1.0              # minpoll 12 maxpoll 17
         server fudge minpoll 12 maxpoll 17
         server statsdir minpoll 12 maxpoll 17
         server filegen minpoll 12 maxpoll 17
         server filegen minpoll 12 maxpoll 17
         server filegen minpoll 12 maxpoll 17
The result is totally bogus, won't parse, and will prevent ntpd from starting up.
If you're going to maintain your own /etc/ntp.conf file, you need to make sure you save a copy to something like /etc/ntp.conf.save.europe (or whatever you prefer), so that you can restore a good working copy after MacOS X munges it beyond recognition.
You will probably also want to change the code in /System/Library/StartupItems/NetworkTime/NetworkTime so as to remove the call to ntpdate and change the invocation of ntpd to include a "-g" option on the command line.
Otherwise, you will probably want to start and stop ntpd manually, outside of the control of MacOS X.


At 8:37 AM -0700 7/20/05, Harry Freeman wrote:
>Perhaps only Apple, or someone that has worked for apple can tell us, but the system probably get the time from either WWV, WWVB and WWVH.