Issue connecting a client to localhost using Java

Question

I'm trying to setup a protected client and protected server connection using sockets. Whenever I run the program I receive a connection error saying the connection was refused. I'm using Java in Eclipse IDE running on MAC OS. Any ideas why this code cannot connect to my localhost?

Protected Client:

public static void main(String[] args) throws Exception 
    {
        String host = "localhost";
        int port = 7999;
        String user = "George";         
        String password = "abc123";     
        Socket s = new Socket(host, port);

        ProtectedClient client = new ProtectedClient();
        client.sendAuthentication(user, password, s.getOutputStream());

        s.close();
    }

Protected Server

public static void main(String[] args) throws Exception 
{
    int port = 7999;    //7999
    ServerSocket s = new ServerSocket(port);
    Socket client = s.accept();

    ProtectedServer server = new ProtectedServer();

    if (server.authenticate(client.getInputStream()))
      System.out.println("Client logged in.");
    else
      System.out.println("Client failed to log in.");

    s.close();
}

When I run the program I receive the following error:

Exception in thread "main" java.net.ConnectException: Connection refused
    at java.net.PlainSocketImpl.socketConnect(Native Method)
    at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:382)
    at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:241)
    at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:228)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:431)
    at java.net.Socket.connect(Socket.java:527)
    at java.net.Socket.connect(Socket.java:476)
    at java.net.Socket.<init>(Socket.java:373)
    at java.net.Socket.<init>(Socket.java:216)
    at ProtectedClient.main(ProtectedClient.java:36)

Have you started your server? Also, it looks like your server will close after one client. — Elliott Frisch
– Elliott Frisch, Commented Nov 19, 2013 at 20:17
@constantlearner there's no usage of proxy in connecting to loopback interface such as localhost — Maciej Dobrowolski
– Maciej Dobrowolski, Commented Nov 19, 2013 at 20:26
It would be good practice to remove the throws Exception from the main method and handle the Exceptions where they occur — JamoBox
– JamoBox, Commented Nov 19, 2013 at 20:46

DoubleDouble · Accepted Answer · 2013-11-19 20:45:04Z

1

I have gotten this error before when using particular sockets. Try a different socket like 5687. (Or if you need that particular socket, try making sure your firewall allows it).

Make sure you call client.close() on the server as well. ~~If your program worked once it might be blocking that port.~~

edited Nov 19, 2013 at 20:45

answered Nov 19, 2013 at 20:38

DoubleDouble

1,49310 silver badges25 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

JamoBox Over a year ago

If that was the case a BindException would be thrown rather than a generic Exception. However, this is still good practice.

KellerCL Over a year ago

Thank you for the client.close() suggestion. I am now receiving "Client logged in." print line.

Collectives™ on Stack Overflow

Issue connecting a client to localhost using Java

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related