I was reading through the thread on this topic towards the end of
march. It was mentioned that when he author multi-threads his ping
program one thread may get the response from another.  It was said this
was expect since ICMP doesn't use ports so the framework can't
determine who sent the original packet.  The proposed solution was to
check and make sure that the incoming source IP matches the thread that
sent it.  I tried implementing this but cannot seem to get it to work.
In my code below when I try to check for the endpoint who sent the
reply I always get an exception.  Any suggestions?
Thanks,
Mark

Here is the code section:
if (ClientSocket.SendTo(sendBuffer, remoteEP) <= 0)
   throw new SocketException();
ClientSocket.BeginReceiveFrom(new byte[sendBuffer.Length + 20], //
Receive byte array
   0,  // offset in byte array
   sendBuffer.Length + 20,   //size to receive
   SocketFlags.None,   //Socket flages
   ref remoteEP,   // endpoint
   new AsyncCallback(RecvCallback),   // Asyn callback
   null);  // object that contains state info

private void RecvCallback(IAsyncResult ar)
{
   int bytesReceived = 0;

   try
   {
       Console.WriteLine(ClientSocket.RemoteEndPoint.ToString());
       bytesReceived = ClientSocket.EndReceiveFrom(ar, ref remoteEP);

       //were any bytes received?
       if (bytesReceived > 0) //Yes
           ResponseTime = s.Peek();
   }

   catch (Exception ex)
   {
       Console.WriteLine(ex.Message);
   }
}

This exception is generated when it hits the line has the
ClientSocket.RemoteEndPoint:
A request to send or receive data was disallowed because the socket is
not connected and (when sending on a datagram socket using a sendto
call) no address was supplied