C#

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

public class UdpSrvrSample
{
    public static void Main()
    {
        byte[] data = new byte[1024];
        IPEndPoint ipep = new IPEndPoint(IPAddress.Any, 7557);
        UdpClient newsock = new UdpClient(ipep);

        Console.WriteLine("Waiting for a client...");

        IPEndPoint sender = new IPEndPoint(IPAddress.Any, 0);

        data = newsock.Receive(ref sender);

        Console.WriteLine("Connection received from {0}", sender.ToString());

        string welcome = "OpticVPS Remote Administration";
        data = Encoding.ASCII.GetBytes(welcome);
        newsock.Send(data, data.Length, sender);

        while (true)
        {
            data = newsock.Receive(ref sender);

            Console.WriteLine(Encoding.ASCII.GetString(data, 0, data.Length));
   

            
            newsock.Send(data, data.Length, sender);

        }
    }
}