/*author: _where
  * A port scanner that takes in three arguments, a host, a starting number for the port range, and the ending number in the range
  * tried this with the arguments - 10.199.212.2, 8079, 8081, and was connected to 8080.
  */
import java.io.*;
import java.net.*;
public class PortScanner {
    public static void main(String[] args) throws FileNotFoundException
    {
        Socket connect = null; long t = 0; PrintStream output = new PrintStream("output.log");
        for (int i = Integer.parseInt(args[1]); i < Integer.parseInt(args[2]); i++)
        {
            try
            {
                t = System.currentTimeMillis(); connect = new Socket(InetAddress.getByName(args[0]), i);
            }
            catch(IOException e)
            {
                output.println("Connection could not be established on port - " + i + " after " + (System.currentTimeMillis() - t) + " ms");
                continue;
            }
            output.println("Connection established on port - " + i + " after " + (System.currentTimeMillis() - t) + " ms");
            try {
                if (connect != null)
                    connect.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
}