Question

Iam尝试从我的客户端向我的服务器发送消息（通过UDP）。服务器应回答此消息，如果客户端收到此答复，则应打印出消息。

如果我在本地网络上运行客户端和服务器，一切正常。如果我尝试通过互联网从我的网络外的另一台PC连接，服务器收到客户端的请求，发回答，但客户端永远不会收到这个答案。客户端和服务器都在NAT后面但是我在服务器的NAT端口转发了端口，服务器得到了自己的DNS。我已经尝试过NAT遍历，但是在接收到客户端的请求后，它给了我与服务器的IPEndPoint相同的IP和端口地址。

我不知道如何解决这个问题，所以我们非常感谢任何指导。

客户端

public static void Main()
{
    Thread receiveThread = new Thread(new ThreadStart(ReceiveData));
    receiveThread.Start();

    object[] oData = {1};
    sendData(oData, 0,0, "Li"); 

    while (true)
    {
        Console.ReadLine();
    }
}


private void receiveData()
{
    string receivePort = 8080;

    Socket client = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
    client.ReceiveTimeout = 1000;
    IPEndPoint end = new IPEndPoint(IPAddress.Any, receivePort);
    client.Bind(end);


    while (true)
    {
        try
        {
            byte[] data = new byte[1024];

            client.Receive(data, 0, data.Length, SocketFlags.None);

            object[] receivedObj = Deserialize(data);

            string sType = (string)receivedObj[3];

            if (sType == "Li")
            {
           console.WriteLine("received Li");
            }
         }
         catch (Exception err)
         {
                Console.WriteLine(err.ToString());
         }
     }
}

public static void sendData(object[] oData, int iFrom, int iTo, string sType)
{
    string sendPort = 17171;

    UdpClient client = new UdpClient();

    string IP = "ThisIsTheDNSofmyServer.com"; //ServerDNS
    //string IP = "192.168.xxx.xxx"; //serverIP in LAN 

    if (IP.StartsWith("T")) 
    {
        IP = (Dns.GetHostAddresses(IP))[0].ToString();
    }

    IPEndPoint remoteEndPoint = new IPEndPoint(IPAddress.Parse(IP), sendPort);

    oData[1] = iFrom;
    oData[2] = iTo;
    oData[3] = sType;

    Byte[] data = Serialize(oData);
    client.Send(data, data.Length, remoteEndPoint);

}

服务器的代码几乎相同：

public static void Main()
{
    Thread receiveThread = new Thread(new ThreadStart(ReceiveData));
    receiveThread.Start();

    while (true)
    {
        Console.ReadLine();
    }
}

private static void ReceiveData()
{
    int receivePort = 17171;
    UdpClient client = new UdpClient(receivePort);

    while (true)
    {
        try
        {
            IPEndPoint anyIP = new IPEndPoint(IPAddress.Any, 0);
            byte[] data = new byte[1024];

            data = client.Receive(ref anyIP);

            object[] receivedObj = Deserialize(data);

            //if I receive data send an Answer
            sendData(receivedObj, 0,0,"Li",anyIP.Address.ToString()); 

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

private static void sendData(object[] oData, int iFrom, int iTo, string sType, string IP)
{
    int sendPort = 8080;
    object[] paket = { oData, iFrom, iTo, sType };

    UdpClient client = new UdpClient();

    IPEndPoint remoteEndPoint = new IPEndPoint(IPAddress.Parse(IP), sendPort); 

    client.Send(data, data.Length, remoteEndPoint);

 }

Answer 1

我认为这是一个端口配置问题，

8080几乎可能被配置为备用http

“必须使用多播端口号” from MSDN

创建用于接收数据报的UdpClient

希望这会有所帮助，祝你好运

克里希纳

Answer 2

在您描述的设置中，您无需执行任何非常规的穿越NAT，您只需将其从服务器发送回客户端;具体来说：您必须发送回终点，即IP 和端口，您已收到它。

client.Send(data, data.Length, remoteEndPoint); // remoteEndPoint is the IPEndPoint you got the datagram on

C＃UDP服务器/客户端 - NAT

2 个答案: