CodeProject: SNTP Client in C#. Free source code and programming help

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Sample Image - ntpclient.jpg

Introduction

Though not obvious, time synchronization is sometimes important. The best example is the Kerberos authentication protocol, which requires the resources to be synchronized within minutes or even seconds, but there are other situations as well. The Network Time Protocol (NTP) and its simplified form (SNTP) are widely used to synchronize network resources, due to their simplicity and effectiveness. There are many programs available that synchronize your PC's clock with that of a time server. Dimension 4 is my favorite.

In case you need time synchronization embedded into your software, here is the C# alternative. It's simple, fast and integrates seamlessly with the .NET platform. There is a Java implementation of a NTP client by Michel Van den Bergh, but I don't have the URL anymore. Maybe Michel reads this and will send me a note.

There are several time severs on the Internet and the list below contains those operated by NIST. If you need more, use a search engine.

Name IP Address Location

time-a.nist.gov 129.6.15.28 NIST, Gaithersburg, Maryland

time-b.nist.gov 129.6.15.29 NIST, Gaithersburg, Maryland

time-a.timefreq.bldrdoc.gov 132.163.4.101 NIST, Boulder, Colorado

time-b.timefreq.bldrdoc.gov 132.163.4.102 NIST, Boulder, Colorado

time-c.timefreq.bldrdoc.gov 132.163.4.103 NIST, Boulder, Colorado

utcnist.colorado.edu 128.138.140.44 University of Colorado, Boulder

time.nist.gov 192.43.244.18 NCAR, Boulder, Colorado

time-nw.nist.gov 131.107.1.10 Microsoft, Redmond, Washington

nist1.datum.com 209.0.72.7 Datum, San Jose, California

nist1.dc.certifiedtime.com 216.200.93.8 Abovnet, Virginia

nist1.nyc.certifiedtime.com 208.184.49.9 Abovnet, New York City

nist1.sjc.certifiedtime.com 208.185.146.41 Abovnet, San Jose, California

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

About the Author

Valer BOCAN

I am currently doing graduate work to get a Ph.D. degree at the Technical University of Timisoara, Romania.

Occupation:	Web Developer
Location:	Romania

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Msgs 1 to 25 of 38 (Total in Forum: 38) (Refresh)

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hangs if no ip

wihe2008

20:27 18 Jul '08

if no ip by this address the program is stop to long. can you help?
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Re: hangs if no ip

wihe2008

20:31 18 Jul '08

by enter ip directly i mean, i m not use dns.
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Re: hangs if no ip

wihe2008

21:55 18 Jul '08

system: WINCE5.0 stop (hangs) here: NTPData = TimeSocket.Receive(...
Sign In·View Thread·PermaLink	2.00/5 (1 vote)

commercial use

harmjonker

7:19 14 Jul '08

Hi Valer, what are the conditions to use your code in commercial environments ? Harm Jonker
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Re: commercial use

Valer BOCAN

23:47 14 Jul '08

Send me a message from my blog at www.dataman.ro. Regards, Valer Delta Forth .NET (www.dataman.ro) World's first Forth compiler for the .NET platform
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Daylight Time saving

XadhoomGrglblstr

23:47 6 Apr '08

Has anyone experienced any problems getting the correct time if the device/computer if the querying computer is set wrongly in another daylight savings period? i.e. if my computer clock is set to Jan 7th 2008 08:00, and i run the code on April 7th 08:00 - my clock will be set to April 7th 09:00 - one hour off. This does not happen if i run this in a date in the same daylight savings period. Alex
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Re: Daylight Time saving [modified]

Geoff Low (NZ)

16:56 5 Jun '08

Hi Alex

Yes I have just had the same problem. It turns out when the code is correcting the date/time for the different time zone it is using the current date/time of the querying computer. If the querying computer is in a different time zone then the offset can be out by 1 hour.

The problem can be solved by replacing the calls to GetUtcOffset() as below:

Replace:
// Take care of the time zone
TimeSpan offspan = TimeZone.CurrentTimeZone.GetUtcOffset(DateTime.Now);
return time + offspan;

With:
// Take care of the time zone
TimeZone currentTimeZone = TimeZone.CurrentTimeZone;
return currentTimeZone.ToLocalTime( time );

This now converts the UTC time to the local time without using the querying computers clock.

Regards
Geoff

modified on Friday, June 6, 2008 12:18 AM

The program block

NanakiFire

4:34 2 Apr '08

The program block, when I compile in debug, it's at line : NTPData = TimeSocket.Receive(ref EPhost); because I recieve nothing from the serveur... Someone have an idea ?
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NTP in Compact Framework

IowaEric

6:56 8 Jun '07

I think someone has already mentioned this, but to use this in Compact Framework, you'll need to change kernel32 to coredll.dll. Also, I found that Active Sync would block NTP. It took me a while to figure that problem out, so I hope it helps somebody else.
Sign In·View Thread·PermaLink	1.69/5 (4 votes)

Re: NTP in Compact Framework

IowaEric

16:51 24 Oct '07

The way that I handled this was to not have the device Active Sync'ed when I called NTP. This wasn't an issue for me because for this project, the devices were never Active Sync'ed after development. I supppose, and when I say suppose, I mean wild guess. If you really had to get around this, you could write an app that was both server and client with a normal port on the client side, and a variable port on the server side so you could find a port that was open. That would be a pretty big project. If the time doesn't need to be so exact, you could probably just do it over a web service.

I should also point out that in Compact Framework, the UDPClient has no timeout. I tried running this in a seperate thread, but we ended up just running NTP in a seperate exe so the main app didn't run out of threads.

Good luck.

NIce article

Vikas Salvi

3:21 3 Mar '07

Really a great class 2 use.Good work buddy btw how can i change the system time through code? bcoz as far as i know we can only read system time in c# Vikas Salvi Programmer Analyst
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Re: NIce article

NetDave

7:48 25 Apr '07

I agree! This is really handy code. As old as this article is, it is still very useful and exactly what I was looking for. A big 5 from me. Vikas Salvi wrote: btw how can i change the system time through code? It's right there in the code - the interop call to SetLocalTime() *QRZ? de WAØTTN*
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Execution on Pocket PC Emulator

Rashmi C

2:16 13 Dec '06

The SNTP C# code works on desktop PC. But while trying it on Pocket PC emulator am unable to receive any packets from the server. Found that Active Sync does not support UDP. Therefore, installed Virtual Machine Network Driver and VMWare. Yet the code does not work. Please help me execute the code on Pocket PC. It is urgent. rashmi chinchkar
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Get Server time

try.kret

18:14 8 Oct '06

This is a good article. I am developing a software that needs synchronization of time from server. But i dont see the way to get server time by using your class. Could you please tell me how? I look forward to hearing from you. Try
Sign In·View Thread·PermaLink	1.00/5 (1 vote)

Re: Get Server time

Valer BOCAN

18:23 8 Oct '06

That is pretty simple. Read the manual You need to instantiate the NTPClient class, then "connect" to the server. After that, have a look at how the ToString() method is implemented. Everything is there. Delta Forth .NET (www.dataman.ro) World's first Forth compiler for the .NET platform
Sign In·View Thread·PermaLink	5.00/5 (1 vote)

Re: Get Server time

try.kret

18:49 8 Oct '06

Yeah, you are right. But to get server time is to call the method ReceiveTimestamp? I notice that both server and local time are the same. Or any other way to get server time?
Sign In·View Thread·PermaLink	3.00/5 (1 vote)

Re: Get Server time

try.kret

16:32 9 Oct '06

Sorry for misunderstanding. I can manage things right now. Thank alot for your nice class and your reply. Try
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Urgent:- Implementation of the Network Time protocol (RFC 13905) in C++

Kulkarni Abhijit

1:49 27 Jul '06

Hi All, Can anybody provide me sample code in C++ for changing the client machine time from TIME SERVER? This is very urgent.. Abhijit
Sign In·View Thread·PermaLink	1.00/5 (1 vote)

Thanks!!

Micah Wedemeyer

5:24 23 Dec '05

Just wanted to say thanks for writing this. I think it will come in handy in my current project.
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Using IP addresses rather than hostnames

MrEyes

6:46 27 May '05

Firstly let me say that this is an excellent class an extremely useful.

That being said, I am encountering a small problem that hopefully somebody could shed some light on.

If I pass an IP address to the SNTPClient constructor it always returns succesful, even if the IP doesnt exist. As an example:


client = new SNTPClient("172.96.211.41"); //this ip doesnt exist and cannot be pinged or telnetted to port 123
client.Connect(true);
Console.Writeline(client.ToString());

Doesnt throw any exceptions and returns this


Leap Indicator: No warning
Version number: 3
Mode: Server
Stratum: Secondary Reference
Local time: 27/05/2005 16:29:39
Precision: 9.5367431640625E-07 s
Poll Interval: 1 s
Reference ID: skylar.fbamedia.co.uk (80.253.108.112)
Root Delay: 34.912109375 ms
Root Dispersion: 90.972900390625 ms
Round Trip Delay: 1 ms
Local Clock Offset: 0 ms

I have to admit, I have no idea where the reference ID is coming from.

If I use a non existant host name (e.g. foobar) it does throw an exception.

post.mode = postmodes.signature;
SELECT everything FROM everywhere WHERE something = something_else;
> 1 Row Returned
> 42

2.00/5 (1 vote)

Need urgent Help

PShweta

0:59 7 Oct '04

Hi!

Indeed a good article. Great job. I was searching for this functionality on net for quiet some time (to access a time server, as this is needed in my project).

I downloaded the source code and rebuilt it. But the app. is not running on my system. It throws an SocketException with Message : "No such Host is known" and Error code : 11001.
I tried to change the Time Server URL but with no succcess. The Exception is thrown while resolving the IP Address from URL in the line

IPHostEntry hostadd = Dns.Resolve(TimeServer);

of NTPClient.cs's Connect function.

Later I read about ur latest NTPClient app in the discussion board. But I'm facing the same problem.
I guess problem is that I'm using a proxy Server, and app is not able to bypass it. I tried to search ways to bypass the proxy server but again no success.

I would be really greatful to you if you could help me in solving this problem, as I need this functionality to access the Time Server to get the current time of any given location, for eg. London, France etc.

With Regards
and lots of thanks in advance
Shweta

1.00/5 (1 vote)

Re: Need urgent Help

Valer BOCAN

1:53 7 Oct '04

Ask the sysadmin to open the port 123 for your machine. The same happens in my office. If I connect to Internet from home, the program works ok. Delta Forth .NET (www.dataman.ro) World's first Forth compiler for the .NET platform
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minor bug : Peer clock precision calculation

EzekielDA

12:40 10 Jun '04

This part of the code :

// Precision (in milliseconds)
public double Precision
{
	get
	{
		return (1000 * Math.Pow(2, NTPData[3]));
	}
}

is wrong; it assumes the precision given in the received data is an unsigned byte instead of a signed byte which leads to abnormal results.

// Precision (in milliseconds)
public double Precision
{
	get
	{
		return (Math.Pow(2, (sbyte)NTPData[3]));
	}
}

should work much better Smile

Re: minor bug : Peer clock precision calculation

Valer BOCAN

7:02 14 Jun '04

The issue was already addressed around September 2003, see the latest version at http://www.dataman.ro/sntp. Thanks for reminding me that I need to update the article on CP. Delta Forth .NET (www.dataman.ro) World's first Forth compiler for the .NET platform
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Doesn't Run on WinXP Pro

sandman_max

3:36 4 May '04

I downloaded the source code and rebuilt it with .NET2003. It runs fine on my Win2000 machine but under WinXP Professional, I get the same exception "An existing connection was forcibly closed by the remote host" that somebody else mentioned. It's socket error code 10054 (WSACONNRESET) if that helps. Does anybody know what's going on?
Sign In·View Thread·PermaLink	3.00/5 (3 votes)

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