Re: ntp setting preferences?

FROM : Walt Pawley
DATE : Fri May 23 22:44:40 2008

At 10:32 AM -0500 5/23/08, Fritz Anderson wrote:
>On 22 May 2008, at 10:52 PM, Walt Pawley wrote:
>

>> At least on older versions of Mac OS X, when one visits the
>> Date & Time prefpane with the Set Date & Time automatically
>> setting checked, the /etc/ntp.conf file gets set to "server
>> [name of server] minpoll 12 maxpoll 17". I'd like to know where
>> the "minpoll 12 maxpoll 17" part comes from. I've been fumbling
>> through various things but have have so far been unsuccessful
>> at locating it.

>
>"Where it comes from" is ambiguous.


Ah. I didn't think it was all that ambiguous. Sorry. What I'm
referring to is that one does not seem to have any control over
whether the "minpoll 12 maxpoll 17" gets appended to the
server(s) chosen in the Date & Time prefpane. In addition,
there's no indication to the operator that the appendage will
be made. IOW, "minpoll 12 maxpoll 17" comes from someplace
that's not readily apparent.

> If you mean "what does it mean,"
>
>    man ntp.conf


I think I have a reasonable idea of what it means.

>Perhaps we could help you better if we knew what you were trying to
>accomplish?


It's because of what it means operationally that I'd like to be
able to modify the "minpoll 12 maxpoll 17". I realize I can do
all manner of sidestepping activities to make this happen.
However, all one has to do is look at their Date & Time
prefpane and they'll get the "minpoll 12 maxpoll 17" back - or
so it seems. A lot of computer clocks will not sync up with a
minpoll of 12.

FWIW: merely finding the text "minpoll" in something was
vexing. Since my first posting, I finally found "minpoll" and
some related text in these two files (they seem to be copies of
one another)

-rwxr-xr-x  1 root  wheel  203528 Sep 22  2002
/System/Library/PrivateFrameworks/Admin.framework/Versions/A/Admin
-rwxr-xr-x  1 root  wheel  203528 Sep 22  2002
/System/Library/PrivateFrameworks/Admin.framework/Versions/Current/Admin

--

After finally finding the above files, I did some further
fiddling which I thought I should post in case someone else
wants to "fix" this problem on their computer(s).

In a snipette from ...

$hexdump -C
/System/Library/PrivateFrameworks/Admin.framework/Versions/Current/Admin
| less

0001c250  65 72 22 00 6d 69 6e 70  6f 6c 6c 00 6d 61 78 70  |er".minpoll.maxp|
0001c260  6f 6c 6c 00 20 00 00 00  25 40 20 25 40 20 25 64  |oll. ...%@ %@ %d|
0001c270  20 25 40 20 25 64 00 00  5f 64 65 73 63 72 69 70  | %@ %d.._descrip|
0001c280  74 69 76 65 4e 61 6d 65  00 00 00 00 5f 61 64 64  |tiveName...._add|
0001c290  72 65 73 73 00 00 00 00  5f 6d 69 6e 50 6f 6c 6c  |ress...._minPoll|
0001c2a0  45 78 70 6f 6e 65 6e 74  00 00 00 00 5f 6d 61 78  |Exponent...._max|
0001c2b0  50 6f 6c 6c 45 78 70 6f  6e 65 6e 74 00 00 00 00  |PollExponent....|
0001c2c0  73 65 74 4d 61 78 50 6f  6c 6c 45 78 70 6f 6e 65  |setMaxPollExpone|
0001c2d0  6e 74 3a 00 6d 61 78 50  6f 6c 6c 45 78 70 6f 6e  |nt:.maxPollExpon|
0001c2e0  65 6e 74 00 73 65 74 4d  69 6e 50 6f 6c 6c 45 78  |ent.setMinPollEx|
0001c2f0  70 6f 6e 65 6e 74 3a 00  6d 69 6e 50 6f 6c 6c 45  |ponent:.minPollE|
0001c300  78 70 6f 6e 65 6e 74 00  61 64 64 72 65 73 73 00  |xponent.address.|

... one can see the minpoll and maxpoll text and the format
string used to create the entry for /etc/ntp.conf and some
other stuff.

Fumbling about with otool, I saw the method below and the close
proximity of the 0x11 and 0xc as immediate constants caught my
eye. Too much a coincidence not to be something.

-[NetworkTimeServer init]:
910729b8        mfspr  r0,lr
910729bc        addis  r2,r12,0x1000
910729c0        stw    r31,0xfffc(r1)
910729c4        addi    r2,r2,0x16a0
910729c8        stw    r0,0x8(r1)
910729cc        addis  r4,r12,0x1000
910729d0        stwu    r1,0xffa0(r1)
910729d4        or      r31,r12,r12
910729d8        lwz    r0,0x4(r2)
910729dc        lwz    r4,0xc84(r4)
910729e0        stw    r3,0x40(r1)
910729e4        addi    r3,r1,0x40
910729e8        stw    r0,0x44(r1)
910729ec        bl      0x91089c70      ; symbol stub for: _objc_msgSendSuper
910729f0        or.    r2,r3,r3
910729f4        beq    0x91072a08
910729f8        li      r0,0x11
910729fc        stw    r0,0x10(r2)
91072a00        li      r0,0xc            < -- 3800000c
91072a04        stw    r0,0xc(r2)
91072a08        lwz    r0,0x68(r1)
91072a0c        addi    r1,r1,0x60
91072a10        lwz    r31,0xfffc(r1)
91072a14        mtspr  lr,r0
91072a18        blr
-[NetworkTimeServer initWithConfigurationString:]:

If I had some idea what I was doing, I could probably tell what
the 91072a00 meant without going to trouble of hunting it up in
the hexdump, like ...

000029f0  7c 62 1b 79 41 82 00 14  38 00 00 11 90 02 00 10  ||b.yA...8.......|
00002a00  38 00 00 0c 90 02 00 0c  80 01 00 68 38 21 00 60  |8..........h8!.`|

I then did this in another Terminal window...

# cd /System/Library/PrivateFrameworks/Admin.framework/Versions/Current/
# ls
Admin          Resources
# cp Admin Admin_copy
# xxd -s 0x2a03 -l 1 Admin
0002a03: 0c                                      .
# echo '0002a03: 06'|xxd -r - Admin
# xxd -s 0x2a03 -l 1 Admin
0002a03: 06                                      .

... fired up System Preferences, clicked on Date & Time, quit
System Preferences and did ...

$ cat /etc/ntp.conf
server time.apple.com minpoll 6 maxpoll 17

So, it would appear that the value 12 for minpoll is, indeed,
"hard wired" in.
--

Walter M. Pawley <<email_removed>>
Wump Research & Company
676 River Bend Road, Roseburg, OR 97470
        541-672-8975