PowerShell – Get/Set Windows Date/Time from NTP

Sometimes w32Time is not available or practical so we get this PowerShell script to pull NTP date/time and set the Windows Date/Time

<#
Majority of code is from:
Chris Warwick, @cjwarwickps, August 2012
chrisjwarwick.wordpress.com
#>

$sNTPServer = 'pool.ntp.org'

function Get-NTPDateTime ([string] $sNTPServer)
{
    $StartOfEpoch=New-Object DateTime(1900,1,1,0,0,0,[DateTimeKind]::Utc)   
    [Byte[]]$NtpData = ,0 * 48
    $NtpData[0] = 0x1B    # NTP Request header in first byte
    $Socket = New-Object Net.Sockets.Socket([Net.Sockets.AddressFamily]::InterNetwork, [Net.Sockets.SocketType]::Dgram, [Net.Sockets.ProtocolType]::Udp)
    $Socket.Connect($sNTPServer,123)
    
    $t1 = Get-Date    # Start of transaction... the clock is ticking...
    [Void]$Socket.Send($NtpData)
    [Void]$Socket.Receive($NtpData)  
    $t4 = Get-Date    # End of transaction time
    $Socket.Close()

    $IntPart = [BitConverter]::ToUInt32($NtpData[43..40],0)   # t3
    $FracPart = [BitConverter]::ToUInt32($NtpData[47..44],0)
    $t3ms = $IntPart * 1000 + ($FracPart * 1000 / 0x100000000)

    $IntPart = [BitConverter]::ToUInt32($NtpData[35..32],0)   # t2
    $FracPart = [BitConverter]::ToUInt32($NtpData[39..36],0)
    $t2ms = $IntPart * 1000 + ($FracPart * 1000 / 0x100000000)

    $t1ms = ([TimeZoneInfo]::ConvertTimeToUtc($t1) - $StartOfEpoch).TotalMilliseconds
    $t4ms = ([TimeZoneInfo]::ConvertTimeToUtc($t4) - $StartOfEpoch).TotalMilliseconds
 
    $Offset = (($t2ms - $t1ms) + ($t3ms-$t4ms))/2
    
    [String]$NTPDateTime = $StartOfEpoch.AddMilliseconds($t4ms + $Offset).ToLocalTime() 

    set-date $NTPDateTime
}

clear

get-date # Get Current Windows Date/Time

set-date "2015-12-2 12:00:00" # Set specific Windows Date/Time

Get-NTPDateTime -sNTPServer $sNTPServer # Get NTP Date/Time and Set Windows Date/Time

GitHub: https://gist.github.com/dkittell/56f957c850f1064cbea0

Reference: chrisjwarwick.wordpress.com