Android Client, Pc Server Socket d'ont work over 3g

Question

I try to create a client server socket beetwen my droid(client) and my PC(server), when i am in local(over wifi) it work perfectely, but when il try over 3G i get this exception when the server try to get clientsocket.getOutputStream()

at java.lang.Thread.run(Unknown Source)
java.net.SocketException: Connection reset
at java.net.SocketInputStream.read(Unknown Source)
at java.net.SocketInputStream.read(Unknown Source)
at java.io.DataInputStream.readUnsignedShort(Unknown Source)
at java.io.DataInputStream.readUTF(Unknown Source)
at java.io.DataInputStream.readUTF(Unknown Source)

What's the probleme, do eny one know the solution of this? help please :-(

The Server

public class Server {

ServerSocket serverSocket;
public LinkedBlockingQueue<CDRecCourseDisplay> recCours;
public LinkedList<ClientMail> clientMails;
static Server server;

public static Server getInstance(){
    if(server == null){
        server = new Server();
    }
    return server;
}

Server() {
    // TODO Auto-generated constructor stub
    try {
        serverSocket = new ServerSocket(54444);
        recCours = new LinkedBlockingQueue<CDRecCourseDisplay>(10);
        clientMails = new LinkedList<ClientMail>();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    this.start();
}

private void start(){
    new Thread(new Runnable() {
        @Override
        public void run() {
            // TODO Auto-generated method stub
            while (true){
                try {
                    Socket socket = serverSocket.accept();
                    new Thread(new Client(socket)).start();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }

            }
        }
    }).start();
}

class Client implements Runnable{

    Socket socket;
    DataInputStream in;
    DataOutputStream  out;

    public Client(Socket socket) {
        // TODO Auto-generated constructor stub
        this.socket = socket;
        if(socket == null) return;
        try {
            InputStream i = socket.getInputStream();
            OutputStream o = socket.getOutputStream();
            in = new DataInputStream(i);
            out = new DataOutputStream(o);

        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    @Override
    public void run() {
        // TODO Auto-generated method stub
        new Thread(new Runnable() {

            @Override
            public void run() {
                // TODO Auto-generated method stub
                while(true){
                    try {
                        out.writeUTF("Test Message");
                    } catch (InterruptedException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    } 
                }
            }
        }).start();

        new Thread(new Runnable() {

            @Override
            public void run() {
                // TODO Auto-generated method stub
                while(true){
                    try {
                        String buf = in.readUTF();  
                        Log.d("MESSAGE", buf);
                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    } 
                }
            }
        }).start();
    }

}

}

and the client

class Client implements Runnable{

    Socket socket;
    DataInputStream in;
    DataOutputStream  out;

    public void run() {
        // TODO Auto-generated method stub
        boolean conected = false;
        while(!conected){
            try {
                Thread.sleep(500);
                socket = new Socket("213.233.216.25", 54444);
                in = new DataInputStream(socket.getInputStream());
                out = new DataOutputStream(socket.getOutputStream());
                conected = true;
            } catch (UnknownHostException e) {
                // TODO Auto-generated catch block
                Log.e("ERROR :", e.getMessage());
            } catch (IOException e) {
                // TODO Auto-generated catch block
                Log.e("ERROR :", e.getMessage());
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                Log.e("ERROR :", e.getMessage());
            }
        }

        new Thread(new Runnable() {

            public void run() {
                // TODO Auto-generated method stub
                while(true){
                    try {
                        String buf = in.readUTF();
                        log.d("MESSAGE", buf);
                        }
                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                }
            }
        }).start();


        new Thread(new Runnable() {

            public void run() {
                // TODO Auto-generated method stub
                while(true){
                    try {
                        out.writeUTF("Test message from the phone");
                    } catch (InterruptedException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                }
            }
        }).start();
    }
}

Add the code you have. This may be a firewall issue? – sealz Jul 19 '11 at 14:12 — sealz, Jul 19 '11 at 14:12

score 2 · Accepted Answer · answered Jul 19 '11 at 14:12

2

Most networks (Wifi and 3G) use NAT. NAT allows outbound connections, but prevents inbound (internet to device) connections.

When your server and device are both on the same network, as in your case, then this works as you are not traversing NAT gateway.

Rationale: what you are trying to do (connecting from internet to device) will not work in most networks.

answered Jul 19 '11 at 14:12

Peter Knego

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1

Hey Peter, thank you for response, do you have something to suggest to me? – user820688 Jul 19 '11 at 14:19
1

In practice NAT is hard to overcome. You might try some form of NAT traversal: http://en.wikipedia.org/wiki/NAT_traversal Mostly it requires you to have a separate server server that helps two parties in establishing a direct (p2p) connection. – Peter Knego Jul 19 '11 at 14:23

Android Client, Pc Server Socket d'ont work over 3g

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