int recv;
byte[] data = new byte[1024];
IPEndPoint ipep = new IPEndPoint(IPAddress.Any, 9050);//定义一网络端点
Socket newsock = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);//定义一个Socket
newsock.Bind(ipep);//Socket与本地的一个终结点相关联
Console.WriteLine("Waiting for a client..");

IPEndPoint sender = new IPEndPoint(IPAddress.Any, port);//定义要发送的计算机的地址
EndPoint Remote = (EndPoint)(sender);//
recv = newsock.ReceiveFrom(data, ref Remote);//接受数据           
Console.WriteLine("Message received from{0}:", Remote.ToString());
Console.WriteLine(Encoding.ASCII.GetString(data, 0, recv));

string welcome = "Welcome to my test server!";
data = Encoding.ASCII.GetBytes(welcome);
newsock.SendTo(data, data.Length, SocketFlags.None, Remote);
while (true)
{
data = new byte[1024];
recv = newsock.ReceiveFrom(data, ref Remote);
Console.WriteLine(Encoding.ASCII.GetString(data, 0, recv));
newsock.SendTo(data, recv, SocketFlags.None, Remote);
}