How to Query an NTP Server using C#?

Question

All I need is a way to query an NTP Server using C# to get the Date Time of the NTP Server returned as either a string or as a DateTime.

How is this possible in its simplest form?

Answer 1

Since the old accepted answer got deleted (It was a link to a Google code search results that no longer exist), I figured I could answer this question for future reference :

public static DateTime GetNetworkTime() {     //default Windows time server     const string ntpServer = "time.windows.com";      // NTP message size - 16 bytes of the digest (RFC 2030)     var ntpData = new byte[48];      //Setting the Leap Indicator, Version Number and Mode values     ntpData[0] = 0x1B; //LI = 0 (no warning), VN = 3 (IPv4 only), Mode = 3 (Client Mode)      var addresses = Dns.GetHostEntry(ntpServer).AddressList;      //The UDP port number assigned to NTP is 123     var ipEndPoint = new IPEndPoint(addresses[0], 123);     //NTP uses UDP      using(var socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp))     {         socket.Connect(ipEndPoint);          //Stops code hang if NTP is blocked         socket.ReceiveTimeout = 3000;               socket.Send(ntpData);         socket.Receive(ntpData);         socket.Close();     }      //Offset to get to the "Transmit Timestamp" field (time at which the reply      //departed the server for the client, in 64-bit timestamp format."     const byte serverReplyTime = 40;      //Get the seconds part     ulong intPart = BitConverter.ToUInt32(ntpData, serverReplyTime);      //Get the seconds fraction     ulong fractPart = BitConverter.ToUInt32(ntpData, serverReplyTime + 4);      //Convert From big-endian to little-endian     intPart = SwapEndianness(intPart);     fractPart = SwapEndianness(fractPart);      var milliseconds = (intPart * 1000) + ((fractPart * 1000) / 0x100000000L);      //**UTC** time     var networkDateTime = (new DateTime(1900, 1, 1, 0, 0, 0, DateTimeKind.Utc)).AddMilliseconds((long)milliseconds);      return networkDateTime.ToLocalTime(); }  // stackoverflow.com/a/3294698/162671 static uint SwapEndianness(ulong x) {     return (uint) (((x & 0x000000ff) << 24) +                    ((x & 0x0000ff00) << 8) +                    ((x & 0x00ff0000) >> 8) +                    ((x & 0xff000000) >> 24)); } 

Note: You will have to add the following namespaces

using System.Net; using System.Net.Sockets; 

Answer 2

This is a optimized version of the function which removes dependency on BitConverter function and makes it compatible with NETMF (.NET Micro Framework)

public static DateTime GetNetworkTime() {     const string ntpServer = "pool.ntp.org";     var ntpData = new byte[48];     ntpData[0] = 0x1B; //LeapIndicator = 0 (no warning), VersionNum = 3 (IPv4 only), Mode = 3 (Client Mode)      var addresses = Dns.GetHostEntry(ntpServer).AddressList;     var ipEndPoint = new IPEndPoint(addresses[0], 123);     var socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);      socket.Connect(ipEndPoint);     socket.Send(ntpData);     socket.Receive(ntpData);     socket.Close();      ulong intPart = (ulong)ntpData[40] << 24 | (ulong)ntpData[41] << 16 | (ulong)ntpData[42] << 8 | (ulong)ntpData[43];     ulong fractPart = (ulong)ntpData[44] << 24 | (ulong)ntpData[45] << 16 | (ulong)ntpData[46] << 8 | (ulong)ntpData[47];      var milliseconds = (intPart * 1000) + ((fractPart * 1000) / 0x100000000L);     var networkDateTime = (new DateTime(1900, 1, 1)).AddMilliseconds((long)milliseconds);      return networkDateTime; }