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

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            Server(10086); //监听10086端口
        }

        /// <summary>
        /// 服务器端
        /// </summary>
        /// <param name="port"></param>
        static void Server(int port)
        {
            try
            {
                UdpClient udpclient = new UdpClient(port);
                while (true)
                {                    
                    IPEndPoint ipendpoint = null;
                    byte[] bytes = udpclient.Receive(ref ipendpoint); //停在这等待数据
                    string data = Encoding.Default.GetString(bytes, 0, bytes.Length);                    

                    Console.WriteLine("{0:HH:mm:ss}->接收数据(from {1}:{2})：{3}", DateTime.Now, ipendpoint.Address, ipendpoint.Port, data);
                }
                udpclient.Close();
            }
            catch (Exception ex)
            {
                Console.WriteLine("{0:HH:mm:ss}->{1}", DateTime.Now, ex.Message);
            }
            Console.ReadKey();
        }
    }
}

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

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            Client("42.121.105.222", 10086, "mzwu.com"); //发送数据
        }

        /// <summary>
        /// 客户端
        /// </summary>
        /// <param name="ip"></param>
        /// <param name="port"></param>
        /// <param name="message"></param>
        static void Client(string ip, int port, string message)
        {
            try
            {
                UdpClient udpclient = new UdpClient();
                IPEndPoint ipendpoint = new IPEndPoint(IPAddress.Parse(ip), port);
                byte[] data = Encoding.Default.GetBytes(message);
                udpclient.Send(data, data.Length, ipendpoint);
                udpclient.Close();

                Console.WriteLine("{0:HH:mm:ss}->发送数据(to {1})：{2}", DateTime.Now, ip, message);
            }
            catch (Exception ex)
            {
                Console.WriteLine("{0:HH:mm:ss}->{1}", DateTime.Now, ex.Message);
            }
            Console.ReadKey();
        }
    }
}