import java.net.*;
import java.io.IOException;

public class LocalPortScanner {

  public static void main(String[] args) {
// first test to see whether or not we can bind to ports
// below 1024
  boolean rootaccess = false;
  for (int port = 1; port < 1024; port += 50) {
    try {
      ServerSocket ss = new ServerSocket(port);
// if successful
      rootaccess = true;
      ss.close();
      break;
    }
      catch (IOException e) {
    }
  }
  int startport = 1;
  if (!rootaccess) startport = 1024;
  int stopport = 65535;
    for (int port = startport; port <= stopport; port++) {
      try {
        ServerSocket ss = new ServerSocket(port);
        ss.close();
      }
      catch (IOException e) {
        System.out.println("Port " + port + " is occupied.");
      }
    }
  }
}