[ntp:questions] Windows won't Sync to NTP server

Ryan Malayter malayter at gmail.com
Mon Mar 31 14:30:51 UTC 2008


On Mar 30, 10:03 pm, ma... at ntp.isc.org (Danny Mayer) wrote:
> ntp 4.2.4p4 does not include that fix nor do any of the tarballs for
> ntp-dev yet. That fix is coming. Martin Burnicki or Ryan Malayter
> provided instructions on how to get w32time to send client packet
> instead of symmetric active packets. The clients are getting synched
> because the restrict statement is denying peers.

Are you sure about that? It seems like that "windows hack" code is
already in there.

My pool NTP server is sending out symmetric-active replies to Windows
clients, even though I have these restrict statements:
    restrict default kod limited nomodify notrap nopeer
    restrict <internal subnet> mask 255.255.252.0 nomodify notrap
    restrict 127.0.0.1

My ntpd version for my pool server is 4.2.4p4 at 1.1520-modena-o
(distributed by Meinberg).

Below is a packet trace from Wireshark, that illustrates the request-
response cycle from what I believe is a Windows user of pool.ntp.org:


***** Request Packet *******
Internet Protocol, Src: 68.152.80.170 (68.152.80.170), Dst:
38.98.155.10 (38.98.155.10)
User Datagram Protocol, Src Port: 62096 (62096), Dst Port: ntp (123)
Network Time Protocol
    Flags: 0x19
        00.. .... = Leap Indicator: no warning (0)
        ..01 1... = Version number: NTP Version 3 (3)
        .... .001 = Mode: symmetric active (1)
    Peer Clock Stratum: secondary reference (3)
    Peer Polling Interval: 10 (1024 sec)
    Peer Clock Precision: 0.015625 sec
    Root Delay:    0.0329 sec
    Root Dispersion:    7.8348 sec
    Reference Clock ID: 66.199.242.154
    Reference Clock Update Time: Mar 31, 2008 13:52:17.9219 UTC
    Originate Time Stamp: Mar 31, 2008 13:52:01.9721 UTC
    Receive Time Stamp: Mar 31, 2008 13:52:02.0000 UTC
    Transmit Time Stamp: Mar 31, 2008 14:09:05.9786 UTC

***** Reply packet **********
Internet Protocol, Src: 38.98.155.10 (38.98.155.10), Dst:
68.152.80.170 (68.152.80.170)
User Datagram Protocol, Src Port: ntp (123), Dst Port: 62096 (62096)
Network Time Protocol
    Flags: 0x19
        00.. .... = Leap Indicator: no warning (0)
        ..01 1... = Version number: NTP Version 3 (3)
        .... .001 = Mode: symmetric active (1)
    Peer Clock Stratum: secondary reference (2)
    Peer Polling Interval: 10 (1024 sec)
    Peer Clock Precision: 0.000001 sec
    Root Delay:    0.0394 sec
    Root Dispersion:    0.0068 sec
    Reference Clock ID: 192.77.171.2
    Reference Clock Update Time: Mar 31, 2008 14:08:21.9166 UTC
    Originate Time Stamp: Mar 31, 2008 14:09:05.9786 UTC
    Receive Time Stamp: Mar 31, 2008 14:09:05.9858 UTC
    Transmit Time Stamp: Mar 31, 2008 14:09:05.9859 UTC





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