FastPortScanner

import java.util.*;


public class FastPortScanner {

    public static void main (String[] args) {


        int start_port = 0, end_port = 0, timeout = 0;
        double init_time = 0, end_time = 0;
        String host_name = "";
        PortScanner port_scanner = null;

        // checking if the user needs help
        if (Arrays.binarySearch(args,"-h") >= 0 || Arrays.binarySearch(args, "--help") >= 0){
            printUsage();
            System.exit(0);
        }
        // checking argument number
        if (args.length < 3 || args.length > 4) {
            System.err.println("[!!!] ERROR: wrong parameters");
            printUsage();
            System.exit(0);
        }

        // setting properties
        try {
            host_name = args[0];
            start_port = Integer.parseInt(args[1]);
            end_port = Integer.parseInt(args[2]);
        } catch (Exception e) {
            System.err.println("[!!!] ERROR: wrong parameters");
            printUsage();
            System.exit(0);
        }

        // setting optional socket's timeout
        try {
            timeout = Integer.parseInt(args[3]);
        } catch (Exception e) {
            // do nothing
        }

        System.out.println("-- Start scanning " + host_name + " from " + start_port + " to " + end_port);
        init_time = System.nanoTime();
        try {
            port_scanner = new PortScanner(start_port, end_port, host_name);
            port_scanner.setTimeout(timeout);
            port_scanner.startScan();
        } catch (HostException | PortException e) {
            port_scanner.stopScan();
            System.err.println("[!!!] ERROR: Port scanner failure");
            System.exit(1);
        }
        end_time = System.nanoTime();
        System.out.println("-- Scan ended --");
        System.out.println("Elapsed time: " + (end_time - init_time) / 1000000000.0 + " seconds");

    }

    public static void printUsage() {
        System.out.println("\n-- Multithreaded port scanner --");
        System.out.println("Usage:");
        System.out.println("java FastPortScanner [host name: string] [start port: int] [end port: int] [timeout: int]");
        System.out.println("n.b. timeout is an optional parameter, by default its value is zero");
    }

}