Question

I am using a simple program to connect to a server:

Here is it:

    public static void main(String[] args) throws Exception {
        String sentence;
        String modsent;

        //input Stream
        BufferedReader fromclient = new BufferedReader(new InputStreamReader(System.in));
        //client Socket
        Socket clientsock = new Socket("stockholm.serverdhse2.se", 9000);
        //output Stream attached to socket
        DataOutputStream serverout = new DataOutputStream(clientsock.getOutputStream());
        //input from Server
        BufferedReader fromserver = new BufferedReader(new InputStreamReader(clientsock.getInputStream()));

        sentence = fromclient.readLine();

        serverout.writeBytes(sentence + "\n");

        modsent = fromserver.readLine();

        System.out.println("From Server: " + modsent);

        clientsock.close();
    }

}

But right now I get the exception:

Exception in thread "main" java.net.ConnectException: Connection refused: connect
    at java.net.DualStackPlainSocketImpl.connect0(Native Method)
    at java.net.DualStackPlainSocketImpl.socketConnect(Unknown Source)
    at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)
    at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)
    at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
    at java.net.PlainSocketImpl.connect(Unknown Source)
    at java.net.SocksSocketImpl.connect(Unknown Source)
    at java.net.Socket.connect(Unknown Source)
    at java.net.Socket.connect(Unknown Source)
    at java.net.Socket.<init>(Unknown Source)
    at java.net.Socket.<init>(Unknown Source)
    at register.main(register.java:22)

What could be the problem?

Answer 1

maybe its only reachable form a range dns server in your network , check with nmap:

nmap -A stockholm.serverdhse2.se -p 9000

wich give me a :

Failed to resolve given hostname/IP: stockholm.serverdhse2.se.

to make sure its a dns issue, try with the ip.
If connects successfully with the ip you got it: “dns problem”