無法通過TCP連接到另一台計算機

Question

我正在一個通過TCP傳輸文件的項目。 它是用.NET 4.7編寫的。 客戶端在同一台計算機上的服務器上連接時，該程序可以運行，但是當我將其發送給朋友並嘗試連接時，出現錯誤：

連接嘗試失敗，因為一段時間后連接方未正確響應，或者建立連接失敗，因為連接的主機未能響應

目前，該程序僅發送有關將被復制的文件的一些信息，並且沒有加密任何內容，因為我什至無法發送這些信息。

這是服務器的代碼（使用Invoke是因為它在單獨的線程上運行）：

    private void Server_Start()
    {


        try
        {
            // Set port on 13000
            int port = 13000;

            //Get the ip adress for the server
            String localIp;

            using (var client = new WebClient())
            {
                // Try connecting to Google public DNS and get the local endpoint as IP
                // If failed to connect set IP as local IP
                if (CheckForInternetConnection())
                {
                    try
                    {
                        using (Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, 0))
                        {
                            socket.Connect("8.8.8.8", 65530);
                            IPEndPoint endPoint = socket.LocalEndPoint as IPEndPoint;
                            localIp = endPoint.Address.ToString();
                        }
                    }
                    catch (Exception e)
                    {
                        localIp = "127.0.0.1";
                    }
                }
                else
                {
                    localIp = "127.0.0.1";
                }
            }


            IPAddress IP = IPAddress.Parse(localIp);

            // Create listener and start listening 
            server = new TcpListener(IP, port);
            server.Start();

            // Buffer for data
            Byte[] bytes = new byte[256];
            String data = string.Empty;
            this.Invoke((MethodInvoker)(() => Log.Items.Add("Server started on ip: " + IP.ToString())));
            while (true)
            {

                // Accepting requests
                TcpClient client = server.AcceptTcpClient();

                // Get the stream object
                NetworkStream stream = client.GetStream();

                // Read length of file name
                byte[] nameLength = new byte[4];
                stream.Read(nameLength, 0, 4);
                int nameSize = BitConverter.ToInt32(nameLength, 0);

                // Read the name of file
                byte[] name = new byte[nameSize];
                stream.Read(name, 0, nameSize);
                String fileName = Encoding.UTF8.GetString(name);

                // Read size of file
                byte[] fileSizeB = new byte[4];
                stream.Read(fileSizeB, 0, 4);
                int fileSize = BitConverter.ToInt32(fileSizeB, 0);

                // Read start signal
                byte[] startB = new byte[9+1];
                stream.Read(startB, 0, 9);
                String start = Encoding.UTF8.GetString(startB);

                this.Invoke((MethodInvoker)(() => Log.Items.Add("Size of name: " + nameSize.ToString())));
                this.Invoke((MethodInvoker)(() => Log.Items.Add("Name of file: " + fileName)));
                this.Invoke((MethodInvoker)(() => Log.Items.Add("File size: " + fileSize.ToString())));
                this.Invoke((MethodInvoker)(() => Log.Items.Add("Start signal: " + start)));

                // Response to client
                byte[] message = Encoding.UTF8.GetBytes("Testmessage");
                stream.Write(message, 0, message.Length);
            }
            server.Stop();
            Log.Items.Add("Server started on ip: " + IP.ToString());
        }
        catch (Exception e)
        {
            this.Invoke((MethodInvoker)(() => Log.Items.Add(e)));
        }

    }

這是客戶端的代碼：

    private void button1_Click(object sender, EventArgs e)
    {
        IPAddress iP = IPAddress.Parse(ConnectIp.Text);
        int port = 13000;
        int buffersize = 1024;

        TcpClient client = new TcpClient();
        NetworkStream netStream;

        // Try to connect to server
        try
        {
            client.Connect(new IPEndPoint(iP, port));
        }
        catch(Exception ex)
        {
            this.Invoke((MethodInvoker)(() => Log.Items.Add(ex.Message)));
            return;
        }

        netStream = client.GetStream();

        String path = "D:\\testingEnv\\test1\\testing\\Matematika\\2017\\Školsko\\2017-SS-skolsko-B-1234-zad.pdf";

        String Filename = Path.GetFileName(path);

        // We wish to send some data in advance:
        // File name, file size, number of packets, send start and send end

        byte[] data = File.ReadAllBytes(path);

        // First packet contains: name size, file name, file size and "sendStart" signal
        byte[] nameSize = BitConverter.GetBytes(Encoding.UTF8.GetByteCount(Filename)); // Int
        byte[] nameB = Encoding.UTF8.GetBytes(Filename);
        byte[] fileSize = BitConverter.GetBytes(data.Length);
        byte[] start = Encoding.UTF8.GetBytes("sendStart");

        // Last packet constains: "sendEnd" signal to stop reading netStream
        byte[] end = Encoding.UTF8.GetBytes("sendEnd");

        // Creating the first package: nameSize, fileName, fileSize and start signal
        byte[] FirstPackage = new byte[4 + nameB.Length + 4 + 9];
        nameSize.CopyTo(FirstPackage, 0);
        nameB.CopyTo(FirstPackage, 4);
        fileSize.CopyTo(FirstPackage, 4 + nameB.Length);
        start.CopyTo(FirstPackage, 4 + nameB.Length + 4);

        // Send the first pckage
        netStream.Write(FirstPackage, 0, FirstPackage.Length);

        byte[] buffer = new byte[30];

        // Read the response
        netStream.Read(buffer, 0, 11);

        netStream.Close();



        client.Close();
    }

一位朋友試圖將端口13000向前移植，但也沒有起作用。 我們甚至嘗試過關閉防火牆，但一無所獲。 我在互聯網上進行搜索，但找不到解決該問題的任何方法。

要注意的一件事是兩個功能都在同一應用程序中。 我不知道這是否是問題的原因。

有人知道這是怎么回事嗎？

提前致謝

Answer 1

您是否嘗試過使用telnet連接到服務器？ “ telnet localhost 13000”或來自具有正確IP和地址nbr的其他計算機？ 調試服務器代碼時，請嘗試該操作。 如果telnet有效，則客戶端代碼有問題。