unable to connect to linux machine through socket

Question

I have aa server running on a linux machine with centos 7. On the machine I run a code the manages client connections to the server. Here is my code:

public class ServerMain_mng {
final static int nPort = 3333;

public static void main(String[] args) throws IOException {
    new ServerMain_mng();
}

public ServerMain_mng(){
    try {
        ServerSocket sSocket = new ServerSocket(3333);
        System.out.println("Server started at: " + new Date());
        System.out.println("===============================================\n");

        while(true) {
            System.out.println("waiting for connection");
            //Wait for a client to connect
            Socket socket = sSocket.accept();
            socket.setSoTimeout(30000);
            //Create a new custom thread to handle the connection
            ClientThread cT = new ClientThread(socket, nPort);
            //Start the thread!
            new Thread(cT).start();  
        }
    } 
    catch(IOException ex) {ex.printStackTrace();}
}}

The problem is that the code does not get past the line Socket socket = sSocket.accept(); when a client tries to connect to the server.

I should note that i run the same code on my laptop, connecting as a client from a local host and it works fine. I checked the port forwarding in the router and the specified ports are open.

What could be the problem? Any ideas how to fix it? any help would be appreciated.

Answer 1

sSocket.accept() is a blocking call, it is supposed to remain blocked untill some client connects to it using the same port where it is listening.

 public class Client {
         final static int nPort = 3333;
         public static void main(String[] args) throws IOException {
         Socket sock=new Socket(IP of Server, nPort)
         System.out.println("connected to: +sock.getRemoteSocketAddress())
      //send additional data needed for the server using the socket's outputputStream
            }
            }

At the server,

 ClientThread cT = new ClientThread(socket);
  //Start the thread!
  new Thread(cT).start();