// This constructor arbitrarily assigns the local port number.
UdpClient udpClient = new UdpClient(11000);
try{
udpClient.Connect("www.contoso.com", 11000);

// Sends a message to the host to which you have connected.
Byte[] sendBytes = Encoding.ASCII.GetBytes("Is anybody there?");

udpClient.Send(sendBytes, sendBytes.Length);

// Sends a message to a different host using optional hostname and port parameters.
UdpClient udpClientB = new UdpClient();
udpClientB.Send(sendBytes, sendBytes.Length, "AlternateHostMachineName", 11000);

//IPEndPoint object will allow us to read datagrams sent from any source.
IPEndPoint RemoteIpEndPoint = new IPEndPoint(IPAddress.Any, 0);

// Blocks until a message returns on this socket from a remote host.
Byte[] receiveBytes = udpClient.Receive(ref RemoteIpEndPoint);
string returnData = Encoding.ASCII.GetString(receiveBytes);

// Uses the IPEndPoint object to determine which of these two hosts responded.
Console.WriteLine("This is the message you received " +
returnData.ToString());
Console.WriteLine("This message was sent from " +
RemoteIpEndPoint.Address.ToString() +
" on their port number " +
RemoteIpEndPoint.Port.ToString());

udpClient.Close();
udpClientB.Close();

}
catch (Exception e ) {
Console.WriteLine(e.ToString());
}