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Thread: Client / Server connection not working except localhost

  1. #1
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    Default Client / Server connection not working except localhost

    I created a server and a client and it's working with localhost. But when using any IP except localhost for the client it won't work. I tested it with both LAN and Hamachi. When using my own Hamachi IP it also won't work, that's why I think it has nothing to do with port forwarding or something like that.


    This is the initialisation code for my server:

    public static void init()
        	{
        		try
        		{	
        			serverSocket = new ServerSocket(port, 4, InetAddress.getByName("localhost"));
        			new ClientThread(serverSocket); // The thread that's sending the data, not important for my problem, because I can't even connect to the server
        		}
        		catch (IOException e)
        		{
        			e.printStackTrace();
        		}
        	}

    And the client code:

    public static void init()
        	{
        		try
        		{
        			clientSocket = new Socket(serverIP, port);
        			System.out.println("Connected!\nBuffering...");
        			in = new ObjectInputStream(clientSocket.getInputStream());
        			out = new ObjectOutputStream(clientSocket.getOutputStream());
        			String name = "Client "+new Random().nextLong();
        			Client.name = name;
        			System.out.println("Buffered\nPinging for 256 bytes...");
        			out.writeObject(name.getBytes());
        			out.flush();
        			long latency = in.readLong();
        			System.out.println("Latency: "+(System.currentTimeMillis()-latency));
     
        			System.out.println("Starting threads...");
        			new ThreadSend(out);
        			new ThreadReceive(in);
        		}
        		catch (IOException e)
        		{
        			e.printStackTrace();
        		}
        	}

    Are there any errors in my code or is it something else?


  2. #2
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    Default Re: Client / Server connection not working except localhost

    Quote Originally Posted by Bingo90 View Post
    But when using any IP except localhost for the client it won't work. I tested it with both LAN and Hamachi. When using my own Hamachi IP it also won't work, that's why I think it has nothing to do with port forwarding or something like that.
    If the server is on a distinct machine from the client, there are (at 99,9%) certainly some administrative issues about ports, firewalls and so on.
    You must assure that the "path" up to your server software is "open" and not blocked by some sw/hw entity. This has nothing to do with programming.
    Andrea, www.andbin.net SCJP 5 (91%) SCWCD 5 (94%)

    Useful links for Java beginners My new project Java Examples on Google Code

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    Default Re: Client / Server connection not working except localhost

    Server and client are on the same computer.

    EDIT: Problem somehow solved itself
    Last edited by Bingo90; March 6th, 2014 at 09:03 AM.

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    Default Re: Client / Server connection not working except localhost

    Quote Originally Posted by Bingo90 View Post
    Server and client are on the same computer.
    If the client connects to "localhost" there are certainly (at 99,9%) no problems. And if your client/server works well in this situation you have done your job as programmer.
    If the client connects to an address that resolves to another machine or even, in the end, arrives at the same client machine but in a way that the connection "enters" from the outside (or at least triggers the local sw firewall) ..... here you can have problems. And here starts your job as network administrator.
    Point.
    Andrea, www.andbin.net SCJP 5 (91%) SCWCD 5 (94%)

    Useful links for Java beginners My new project Java Examples on Google Code

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