Get the exact time for a remote server

Question

In C#, how do I query a remote server for its current time?

Similar functionality to

net time \\servername

but returning a datestamp that includes seconds.

Thanks

Answer 1

You can use the NetRemoteTOD function.

An example from http://bytes.com/groups/net-c/246234-netremotetod-usage:

// The pointer.
IntPtr pintBuffer = IntPtr.Zero;

// Get the time of day.
int pintError = NetRemoteTOD(@"\\sony_laptop", ref pintBuffer);

// Get the structure.
TIME_OF_DAY_INFO pobjInfo = (TIME_OF_DAY_INFO)
Marshal.PtrToStructure(pintBuffer, typeof(TIME_OF_DAY_INFO));

// Free the buffer.
NetApiBufferFree(pintBuffer);

Answer 2

Simple Network Time Protocol Client

Answer 3

You can try getting the daytime on port 13:

System.Net.Sockets.TcpClient t = new System.Net.Sockets.TcpClient ("yourmachineHOST", 13);
System.IO.StreamReader rd = new System.IO.StreamReader (t.GetStream ()); 
Console.WriteLine (rd.ReadToEnd ());
rd.Close();
t.Close();

Answer 4

If you have access to the filesystem of the remote system with a UNC path (like \\remotehost\foo\bar; for instance using Windows Explorer), you can retrieve remote datetime, even if it's not a Windows system, with following workaround. Create a dummy file, read it's write time and throw it away. It works also for local host.

public DateTime filesystemDateTime(string path)
{
    //create temp file
    string tempFilePath = Path.Combine(path, "lampo.tmp");
    using (File.Create(tempFilePath)) { }
    //read creation time and use it as current source filesystem datetime
    DateTime dt = new FileInfo(tempFilePath).LastWriteTime;
    //delete temp file
    File.Delete(tempFilePath);

    return dt;
}

Answer 5

Using the C# NTP client in Reed Copsey (& David Laing) answer, you can get a time "now" stamp (in ms) from a domain controller / NTP server using:

InternetTime.SNTPClient sntp = new InternetTime.SNTPClient("ntp1.ja.net");
sntp.Connect(false); // true to update local client clock
DateTime dt = sntp.DestinationTimestamp.AddMilliseconds(sntp.LocalClockOffset);
string timeStampNow = dt.ToString("dd/MM/yyyy HH:mm:ss.fff");

Answer 6

Below is a more complete implementation.

Usage: DateTime? now = RemoteTOD.GetNow(@"\\ServerName");

using System;
using System.ComponentModel;
using System.Runtime.InteropServices;

//https://docs.microsoft.com/en-us/windows/desktop/api/lmremutl/nf-lmremutl-netremotetod
public static class RemoteTOD {

    // Important: CharSet must be Unicode otherwise error 2184 is returned
    [DllImport("netapi32.dll", SetLastError=true, CharSet=CharSet.Unicode)]
    private static extern int NetRemoteTOD(String UncServerName, ref IntPtr BufferPtr);

    [DllImport("netapi32.dll")]
    private static extern void NetApiBufferFree(IntPtr bufptr);

    public static DateTime? GetNow(String serverName, bool throwException = false) {
        IntPtr ptrBuffer = IntPtr.Zero;
        int result = NetRemoteTOD(serverName, ref ptrBuffer);
        if (result != 0) {
            if (throwException)
                throw new Win32Exception(Marshal.GetLastWin32Error());
            return null;
        }

        TIME_OF_DAY_INFO tod = (TIME_OF_DAY_INFO) Marshal.PtrToStructure(ptrBuffer, typeof(TIME_OF_DAY_INFO));
        NetApiBufferFree(ptrBuffer); // must be freed using NetApiBufferFree according to the documentation

        //DateTime d0 = new DateTime(1970,1,1);
        //d0 = d0.AddSeconds(tod.elapsedt);
        DateTime nowUtc = new DateTime(tod.year, tod.month, tod.day, tod.hour, tod.minute, tod.second, 10 * tod.hunds);
        DateTime now = nowUtc.ToLocalTime();
        return now;
    }
}

[StructLayout(LayoutKind.Sequential)]
public struct TIME_OF_DAY_INFO {

    ///<summary>The number of seconds since 00:00:00, January 1, 1970, GMT.</summary>
    public int elapsedt;

    ///<summary>The number of milliseconds from an arbitrary starting point (system reset). Typically, this member is read twice,
    ///once when the process begins and again at the end. To determine the elapsed time between the process's start and finish,
    ///you can subtract the first value from the second.</summary>
    public int msecs;

    ///<summary>The current hour. Valid values are 0 through 23.</summary>
    public int hour;

    ///<summary>The current minute. Valid values are 0 through 59.</summary>
    public int minute;

    ///<summary>The current second. Valid values are 0 through 59.</summary>
    public int second;

    ///<summary>The current hundredth second (0.01 second). Valid values are 0 through 99.</summary>
    public int hunds;

    ///<summary>The time zone of the server. This value is calculated, in minutes, from Greenwich Mean Time (GMT). For time zones
    ///west of Greenwich, the value is positive; for time zones east of Greenwich, the value is negative. A value of –1 indicates
    ///that the time zone is undefined.</summary>
    public int timezone;

    ///<summary>The time interval for each tick of the clock. Each integral integer represents one ten-thousandth second (0.0001 second).</summary>
    public int tinterval;

    ///<summary>The day of the month. Valid values are 1 through 31.</summary>
    public int day;

    ///<summary>The month of the year. Valid values are 1 through 12.</summary>
    public int month;

    ///<summary>The year.</summary>
    public int year;

    ///<summary>The day of the week. Valid values are 0 through 6, where 0 is Sunday, 1 is Monday, and so on.</summary>
    public int weekday;
}