PortScanner

import java.net.*;



class PortScanner

{

    public static void main(String [] args)

    {

        int start = 0;

        int end = 65535;

        String hostname = "localhost";



        if(args.length > 0)

            hostname = args[0];



        if(args.length > 1)

            start = Integer.parseInt(args[1]);



        if(args.length > 2)

            end = Integer.parseInt(args[2]);



        for(int port = start; port <= end; port++)

        {

                try

                {

                Socket socket = new Socket();

                socket.connect(new InetSocketAddress(hostname, port), 1);

                socket.close();

                System.out.println("Port " + port + " is open.");

                }



                catch (Exception ex)

                {

            }

        }

    }

}