In this C# tutorial we're going to learn how to ping a host over a network or the Internet using C#.Furthermore the ping is going to be executed asynchronously so that our application doesn't have to wait for the ping.

Designing the applicationStart Visual Studio 2005 or whatever you prefer to use, and put up a form similar to the one below.The important controls are the TextBoxes txtIP,txtResponse (multiline) and a Button btnPing.

using System.Threading;
using System.Net.NetworkInformation;

Inside the class declare these two objects that we'll want accessible later from inside the methods:

// Counts the pings
private int pingsSent;
// Can be used to notify when the operation completes
AutoResetEvent resetEvent = new AutoResetEvent(false);

Now we can move onto coding.

Writing the codeWe'll start with the Click event of btnPing where everything starts:

private void btnPing_Click(object sender,EventArgs e)
{
     // Reset the number of pings
     pingsSent = 0;
     // Clear the textbox of any previous content
     txtResponse.Clear();
     txtResponse.Text  += "Pinging" + txtIP.Text + " with 32bytes of
     data:\r\n\r\n";
     // Send the ping
     SendPing();
}

There we prepare things up,and call the SendPing() method:

private void SendPing()
{
     System.Net.NetworkInformation.PingpingSender = new
                        System.Net.NetworkInformation.Ping();
     // Create an event handler for ping complete
     pingSender.PingCompleted += new
                        PingCompletedEventHandler(pingSender_Complete);
     // Create a buffer of 32 bytes of data to be transmitted.
     byte []packetData = 
                        Encoding.ASCII.GetBytes("................................");
     // Jump though 50 routing nodes tops, and don't fragment the packet
     PingOptions packetOptions = new PingOptions(50, true);
     // Send the ping asynchronously
     pingSender.SendAsync
                                    (txtIP.Text,5000,packetData,packetOptions,resetEvent);
}

First of all you probably noticed that we still declare the Ping object using its full namespace.That's because otherwise the compiler will confuse it with the Ping namespace.On the line following that,we set an event handler for PingCompleted to pingSender_Complete,and that's where our next chunk of code will be located. The event will fire,as you might've guessed, when the packet comes back,or when it doesn't and the request has timed out. packetData is the content of the package.We made it 32 bytes in size by having 32 characters in it.It doesn't matter what the characters are, so you can put it your little easter egg in there if you wish to. We don't want the packet to be defragmented, since the returned result would not be a true number of milliseconds that the packet took to go to the destination and back.Finally the last method sends the ping to the desired host (IP address or host name),with a timeout of 5000 milliseconds and the options specified earlier (should not exceed 50 routing nodes,and should not be fragmented.)

This moves us to our next piece of code,which is the pingSender_Complete event:

private void pingSender_Complete(object sender, PingCompletedEventArgs e)
{
     // If the operation was canceled, display a message to the user.
     if (e.Cancelled)
     {
          txtResponse.Text += "Ping was canceled...\r\n";
          // The main thread can resume
          ((AutoResetEvent)e.UserState).Set();
     }
     else if (e.Error != null)
     {
          txtResponse.Text += "An error occured: " + e.Error + "\r\n";
          // The main thread can resume
          ((AutoResetEvent)e.UserState).Set();
     }
     else
     {
          PingReply pingResponse = e.Reply;
          // Call the method that displays the ping results,and pass the
          information with it
          ShowPingResults(pingResponse);
     }
}

This piece of code fires when the package got back or when the timeout arrived.Depending on the response,we either show the negative result and tell the main thread it can resume,or call the method that displays the results,which is ShowPingResults():

public void ShowPingResults(PingReply pingResponse)
{
     if(pingResponse == null)
     {
          // We got no response
          txtResponse.Text += "There was no response.\r\n\r\n";
          return;
     }
     else if (pingResponse.Status == IPStatus.Success)
     {
          // We got a response, let's see the statistics
          txtResponse.Text += "Reply
                                          from"+pingResponse.Address.ToString()
                                          +":bytes="+pingResponse.Buffer.Length+"
                                          time=" + pingResponse.RoundtripTime+
                                          " TTL=" + pingResponse.Options.Ttl + "\r\n";
     }
     else
     {
          // The packet didn't get back as expected, explain why
          txtResponse.Text += "Pingwasunsuccessful:" +pingResponse.Status +
                                          "\r\n\r\n";
     }
     // Increase the counter so that we can keep track of the pings sent
     pingsSent++;
     // Send 4 pings
     if (pingsSent < 4)
     {
          SendPing();
     }
}

Here we do some additional checking.First we make sure that we got the parameter passed in correctly - pingResponse of type PingReply - since it holds all the information about how the package got back.We display that information much like MS-DOS displays it when using the ping command but without the final statistics.However,just like the MS-DOS ping command works by default, we do run 4 pings per each request,so at the end of ShowPingResults() we call the SendPing() method all over again,unless we already did that 4 times.

You're now ready to compile,run and do some pinging!The example below pinged the yahoo.com server IP. Just don't do it too much or you might take the Yahoo server down.