Windows sync time service - w32tm

由 datahunter 在三, 10/07/2013 - 10:41 發表

最後更新: 2018-12-20

介紹

Windows sync time Service

Service name: W32Time

# Check Service Status

sc query w32time

SERVICE_NAME: w32time
        TYPE               : 20  WIN32_SHARE_PROCESS
        STATE              : 4  RUNNING
                                (STOPPABLE, NOT_PAUSABLE, ACCEPTS_SHUTDOWN)
        WIN32_EXIT_CODE    : 0  (0x0)
        SERVICE_EXIT_CODE  : 0  (0x0)
        CHECKPOINT         : 0x0
        WAIT_HINT          : 0x0

register 與 unregister

unregister - unregister service and remove all configuration

C:\>w32tm /register

The following error occurred: Access is denied. (0x80070005)

PC Resync Time

Usage

# Sending resync command to local computer...

# The computer did not resync if no time data was available.

w32tm /resync [/nowait] [/rediscover]

Opts

/nowait - do not wait for the resynchronize to occur; return immediately.

/rediscover - Redetect the network configuration and rediscover network sources, then resynchronize.

i.e.

C:\> w32tm /resync

Sending resync command to local computer
The command completed successfully.

設定與誰 sync 時間

External source

# 此設定多數是在 PDC 及 Standalone 機上

# /manualpeerlist 是用 space delimited 每一架 server

# syncfromflags:<source> - sets what sources the NTP client should sync from.
# <source> should be a comma separated list of these keywords
# MANUAL - include peers from the manual peer list
# DOMHIER - sync from a DC in the domain hierarchy

w32tm /config /manualpeerlist:stdtime.gov.hk /syncfromflags:manual /reliable:yes

# update - notifies the time service that the configuration has changed, causing the changes to take effect.

w32tm /config /update

All other DCs

w32tm /config /syncfromflags:domhier /update

Remark

You can check the registry entries if the domain controller is using "NTP" (should be on PDC) or "NT5DS" (on non-PDC):

"Type" under "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters"

Status

w32tm /query /status

Leap Indicator: 0(no warning)
Stratum: 2 (secondary reference - syncd by (S)NTP)
Precision: -6 (15.625ms per tick)
Root Delay: 0.0312500s
Root Dispersion: 7.7758309s
ReferenceId: 0x768F1152 (source IP:  118.143.17.82)
Last Successful Sync Time: 1/21/2015 12:53:12 PM
Source: stdtime.gov.hk
Poll Interval: 10 (1024s)

w32tm /query /configuration

[配置]

EventLogFlags: 2 (本地)
AnnounceFlags: 10 (本地)
TimeJumpAuditOffset: 28800 (本地)
MinPollInterval: 10 (本地)
MaxPollInterval: 15 (本地)
MaxNegPhaseCorrection: 54000 (本地)
MaxPosPhaseCorrection: 54000 (本地)
MaxAllowedPhaseOffset: 1 (本地)

.................................

[TimeProviders]

NtpClient (本地)
DllName: C:\Windows\system32\w32time.dll (本地)
Enabled: 1 (本地)
InputProvider: 1 (本地)
AllowNonstandardModeCombinations: 1 (本地)
ResolvePeerBackoffMinutes: 15 (本地)
ResolvePeerBackoffMaxTimes: 7 (本地)
CompatibilityFlags: 2147483648 (本地)
EventLogFlags: 1 (本地)
LargeSampleSkew: 3 (本地)
SpecialPollInterval: 900 (本地)
Type: NTP (本地)
NtpServer: stdtime.gov.hk (本地)

MinPollInterval

The default value for domain controllers is "6" (64 sec)

The default value for domain members is "10" (1024 sec ~ 17.1 min)

The default value for stand-alone clients and servers is "10"

* Unit: units of 2^n seconds

* To make changes to this entry effective, at the command line, type:

w32tm /config /update

MaxPollInterval

Domain controllers: 10 (17.1 min.)

Domain members: 15 (9.1 hr.)

設定幾耐 sync 一次時鍾

所在 regtry

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpClient

SpecialInterval

SpecialInterval = 0x1

When we add the 0x1 we are telling W32Time to use the registry key "SpecialPollInterval"

instead of the automagic MinPollInterval("0xA") and MaxPollInterval("0xF").

SpecialPollInterval

Default: 604800, Unit: second

Example 1: 設定每 3600 秒 sync 一次時間

net stop w32time

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters]
"NtpServer"="time.google.com,0x1"

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpClient]
"SpecialPollInterval"=dword:00000e10

net start w32time

Remark

0x01 SpecialInterval
0x02 UseAsFallbackOnly
0x04 SymmetricActive
0x08 Client

Example 2: 用 MaxPollInterval 及 SpecialPollInterval 去 polling

# Server 後不加 "0x1"

net stop w32time

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters]
"NtpServer"="time.google.com"

net start w32time

有關 regetry key

HKLM\SYSTEM\CurrentControlSet\services\W32Time\Parameters

# 設定與什麼 Server 去 sync 時間

NtpServer # String

HKLM\SYSTEM\CurrentControlSet\services\W32Time\Config

MaxPollInterval

Hex (Value "a" ~ 17min)

在 AD Domain 的 time source

在 domain 環境內, Time Source 由 PDC 提供

PC <--- DC <--- DC (PDC emulator ) <--- forest root DC (PDC emulator ) <--- Internet time source

找出那架機是 PDC

netdom /query fsmo

Remark

Netdom is a command-line tool that is built into Windows Server 2008.

Server 2003 SP2

https://www.microsoft.com/en-us/download/details.aspx?id=15326

domain to monitor

To configure a domain controller in the parent domain as a reliable time source:

w32tm /config /reliable:yes /update

monitor

# domain to monitor

C:\>w32tm /monitor

ns1.mydomain *** PDC *** [10.0.203.21]:
    ICMP: 0ms delay.
    NTP: +0.0000000s offset from ns1.mydomain
        RefID: 'LOCL' [76.79.67.76]

P.S.

XP 及 Server03 的 default time.windows.com 已不存在 (20130710)

GPO

The allowed time skew can be configured using the Maximum tolerance for computer clock synchronization GPO setting

Computer Configuration\Windows Settings\Security Settings\Account Policies\Kerberos Policy

It determines the maximum time skew (in minutes) that Windows will tolerate between client and a server clocks in a Windows Kerberos environment. Default 5 min.

Setting the time skew too high creates a higher risk for replay attacks.

How do I force all clients in domain to syncronize time remotely

a startup script containing:

w32tm /config /syncfromflags:domhier /update

;After that you have to run:
net stop w32time
net start w32time

Example

# 在 DC 設定 NTP Source

w32tm /config /syncfromflags:manual /manualpeerlist:"time.google.com" /reliable:yes /update

# 套用 Setting

net restart w32time

# 查看現在的設定

w32tm /query /status

# AD output

Leap Indicator: 0(no warning)
Stratum: 2 (secondary reference - syncd by (S)NTP)
Precision: -23 (119.209ns per tick)
Root Delay: 0.0379524s
Root Dispersion: 51.6594092s
ReferenceId: 0xD8EF2304 (source IP:  216.239.35.4)
Last Successful Sync Time: 12/17/2018 12:45:07
Source: time.google.com
Poll Interval: 6 (64s)

# DC Member output

Leap Indicator: 0(no warning)
Stratum: 3 (secondary reference - syncd by (S)NTP)
Precision: -23 (119.209ns per tick)
Root Delay: 0.0408734s
Root Dispersion: 0.1270583s
ReferenceId: 0xC0A85064 (source IP:  192.168.80.100)
Last Successful Sync Time: 12/17/2018 3:14:46 PM
Source: ad01.local
Poll Interval: 8 (256s)

Spike

LargePhaseOffset

Specifies that a time offset greater than or equal to this value in 10^7 seconds is considered a spike.

A network disruption such as a large amount of traffic might cause a spike.

The default value on domain members is 50000000.

HoldPeriod

Controls the period of time for which spike detection is disabled in order to bring the local clock into synchronization quickly.

A spike is a time sample indicating that time is off a number of seconds,

and is usually received after good time samples have been returned consistently.

The default value on domain members is 5. The default value on stand-alone clients and servers is 5.

SpikeWatchPeriod

Specifies how long, in seconds, that a suspicious time offset must persist before it is accepted as correct.

if the client gets into SPIKE state, the client does not sync its time.

Regetry Setting - MaxPosPhaseCorrection and MaxNegPhaseCorrection

If the service determines that a change larger than this is required, it logs an event instead.

Specifies the largest positive time correction in seconds that the service makes.

The default value for domain members is 0xFFFFFFFF.

The default value for stand-alone clients and servers is 54,000 (15 hrs).

Regetry Setting - MaxAllowedPhaseOffset

Specifies the maximum offset (in seconds) for which W32Time attempts to adjust the computer clock by using the clock rate.

When the offset exceeds this rate, W32Time sets the computer clock directly. The default value for domain members is 300.

The default value for stand-alone clients and servers is 1.

Other

# To synchronize the DC's current system time with an external time server

W32tm /resync /computer:time.windows.com /nowait

# To force a computer to synchronize its time with a specific DC

net time \\<DC_name_or_IP> /set /y

瀏覽次數： 5413

夢想家

Windows sync time service - w32tm

介紹

目錄

Windows sync time Service

register 與 unregister

PC Resync Time

設定與誰 sync 時間

External source

Status

設定幾耐 sync 一次時鍾

有關 regetry key

在 AD Domain 的 time source

GPO

How do I force all clients in domain to syncronize time remotely

Example

Spike

Regetry Setting - MaxPosPhaseCorrection and MaxNegPhaseCorrection

Regetry Setting - MaxAllowedPhaseOffset

Other