Problemas com alocação de porta via ServerSocket no Linux

public class Server {

	public static void main(String[] args) {

		try {
			ServerSocket ss = new ServerSocket(8000);

			while (true) {
				System.out.println("\nServidor esperando requisição...");
				Socket socket = ss.accept();
				ObjectInputStream objectInputStream = new ObjectInputStream(socket.getInputStream());				
				Task task = (Task)objectInputStream.readObject();

				Principal principal = new Principal();
				principal.executeRobot();				
				
				task.setValue(socket.getInetAddress().toString());
				
				ObjectOutputStream objectOutputStream = new ObjectOutputStream(socket.getOutputStream());
				objectOutputStream.writeObject(task);
				objectOutputStream.close();

				objectInputStream.close();
				socket.close();

			}

		} catch (Exception e) {
			e.printStackTrace();
		}

	}
	
	
}

public class Client {

	private static final int PORTA_SERVIDOR = 8000;

	public static void main(String[] args) {
		
		try {
			ArrayList<String> ips = new ArrayList<String>();
			ips.add("192.168.99.164");
			//ips.add("192.168.99.150");
			
			Thread.sleep(2000);
				
			for (String ip : ips) {
				AccessServer accessServer = new AccessServer(ip, PORTA_SERVIDOR);
				Thread t = new Thread(accessServer);
				t.start();
			}
				

		} catch (Exception e) {
			System.out.println(e);
			e.printStackTrace();
		}

	}

}

Connection refused: connect

java -jar Server.jar