Tcp intranet troubles with connection C#

Question

I'm having trouble establishing a TCP connection between two devices connected on the same wifi network (a PC and a mobile), the code seems to be fine, but the client (in my case, the phone) keeps trying to connect and the server (the pc ), wait for a connection and in the end nothing happens. I tried to configure my firewall on the PC, but it still doesn't work. I would like that these applications could work on other PCs without configuring so much and in a very simple way, since it is a tool to expose in the university.

I also gave him the permissions to connect to the internet to the mobile application

Here I leave the code of the pc:

class TcpServerCode
{
    IPEndPoint ipEnd;
    Socket sock;

    public TcpServerCode(int port)
    {
        ipEnd = new IPEndPoint(IPAddress.Any, port);
        sock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);
        sock.Bind(ipEnd);
    }

    public static string curMsg = "Stopped";

    public void StartServer()
    {
        try
        {
            curMsg = "Starting...";
            sock.Listen(100);
            curMsg = "Running and waiting to receive file.";
            Socket clientSock = sock.Accept();
            byte[] clientData = new byte[1024];
            int receivedBytesLen = clientSock.Receive(clientData);
            curMsg = "Receiving data...";
            int fileNameLen = BitConverter.ToInt32(clientData, 0);
            string getStr = Encoding.ASCII.GetString(clientData, 4, fileNameLen);

            Form1.Singletone.ConsoleLog(getStr);
            clientSock.Close();
        }
        catch (Exception ex)
        {
            curMsg = "Error.";
        }
    }
}

And here the mobile:

class TcpClientCode
{
    public static string curMsg = "Idle";

    public static void SendComand(string comand)
    {
        try
        {
            IPAddress[] ipAddress = Dns.GetHostAddresses("localhost");
            IPEndPoint ipEnd = new IPEndPoint(ipAddress[0], 5656);
            Socket clientSock = new Socket(AddressFamily.InterNetwork,
                SocketType.Stream, ProtocolType.IP);
            byte[] fileNameByte = Encoding.ASCII.GetBytes(comand);
            byte[] clientData = new byte[4 + fileNameByte.Length];

            curMsg = "Connection to server ...";
            clientSock.Connect(ipEnd);
            curMsg = "Command sending...";
            clientSock.Send(clientData);
            curMsg = "Disconnecting...";
            clientSock.Close();
            curMsg = "transferred.";
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }
    }
}

you are using "localhost" on the device, thus trying to connect to the device itself, and not your PC, use the PCs ip address — SushiHangover, Mar 14 '20 at 03:40
I already tried it and it still crashes when trying to connect with PC — Sergio Ribera, Mar 14 '20 at 04:00
Yes man, was that, do you know how I can get the correct ip of the machine? — Sergio Ribera, Mar 14 '20 at 04:14

score 0 · Accepted Answer · answered Mar 14 '20 at 04:24

For those who want to know, I solved it thanks to SushiHangover, and the problem was that I had to make my client connect to the server's IPv4, because it is in an intranet system.

And to get local Ip Address:

public static string GetLocalIPAddress()
{
    var host = Dns.GetHostEntry(Dns.GetHostName());
    foreach (var ip in host.AddressList)
    {
        if (ip.AddressFamily == AddressFamily.InterNetwork)
        {
            return ip.ToString();
        }
    }
    throw new Exception("No network adapters with an IPv4 address in the system!");
}

To check if you're connected or not:

System.Net.NetworkInformation.NetworkInterface.GetIsNetworkAvailable();

Information taken from Get local IP address

Tcp intranet troubles with connection C#

1 Answers1