networkJava.java

import java.io.IOException;
import java.lang.reflect.Array;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.UnknownHostException;
import java.util.ArrayList;

//import org.apache.log4j.Logger;


/**
 * Created by scott on 6/28/16.
 *
 */
public class networkJava {

//    private final static Logger logger = Logger.getLogger(networkJava.class);
    private int total_ips_scanned = 0;

//        String[] subnets = {"192.168.","10.0.","10.1.","10.10.","152.10.","200.200."};
//    String[] subnets = {"152.10."};
String[] subnets = {"192.168."};

    public static void main(String args[]) {
        networkJava nj = new networkJava();
        nj.searchHosts();
    }

    public ArrayList<String> searchHosts() {
        long startTime = System.currentTimeMillis();
        ArrayList<String> result = null;
        for (String subnet : subnets) {
            result = searchAllHosts(subnet);
            result.forEach(System.out::println);
            if (!result.isEmpty()) {
                break;
            }
        }
        long endTime = System.currentTimeMillis();
        System.out.println("That took " + (endTime - startTime) + " milliseconds");
        return result;
    }

    /**
     * Searches for all hosts
     * @return list of hosts found
     */
    public ArrayList<String> searchAllHosts(String ip) {
//        logger.info("Searching for host on subnet " + ip);
        ArrayList<String> allHosts;
        ArrayList<String> foundHosts = new ArrayList<>();
        for (int i=0;i<255;i++) {
            allHosts = findAllHosts(ip + i);
            if(!allHosts.isEmpty()) {
//                System.out.println("Network detected, stopping...");
//                System.out.println("All devices found: ");
                for (String allHost : allHosts) {
                    System.out.print("IP: " + allHost);
                    foundHosts.add(allHost);
                    InetAddress byName = null;
                    try {
                        byName = InetAddress.getByName(allHost);
                    } catch (UnknownHostException e) {
//                        logger.error("Error while scanning network");
//                        logger.error("Reason: " + e);
                        System.out.println("error");
                    }
                    assert byName != null;
                    String hostName = byName.getHostName();
                    System.out.println("Hostname: " + hostName);
                }
//                break;
            }
        }
//        for(String hostsFound : foundHosts) {
//            logger.info("Found host: " + hostsFound);
//        }

        return foundHosts;
    }

    /**
     *
     * @param subnet -
     * @return -
     */
    private ArrayList<String> findAllHosts(String subnet){
        int timeout=10;
        ArrayList<String> ips = new ArrayList<>();
        for (int i=1;i<255;i++){
            String host=subnet + "." + i;
//            System.out.println(host);
            setTotal_ips_scanned(getTotal_ips_scanned() + 1);
            try {
                if(isReachable(host,10)) {

//                }
//                if (InetAddress.getByName(host).isReachable(timeout)){
                    InetAddress byName = InetAddress.getByName(host);
                    String hostName = byName.getHostName();
//                    logger.info(hostName);
                    System.out.println(host);
                    if (hostName.contains("rpi")) {
//                        System.out.println(hostName);
                        ips.add(host);
                    }
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return ips;
    }

    /**
     *
     * @param ip -
     * @return -
     */
    public boolean ipIsReachable(String ip) {
        int timeout = 1000;
        boolean res = false;
        try {
            res = InetAddress.getByName(ip).isReachable(timeout);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return res;
    }

    private static boolean isReachable(String addr, int timeOutMillis) {
        // Any Open port on other machine
        // openPort =  22 - ssh, 80 or 443 - webserver, 25 - mailserver etc.
        try {
            try (Socket soc = new Socket()) {
                soc.connect(new InetSocketAddress(addr, 22), timeOutMillis);
            }
            return true;
        } catch (IOException ex) {
            return false;
        }
    }

    public void setTotal_ips_scanned(int total) {
        total_ips_scanned = total;
    }

    public int getTotal_ips_scanned() {
        return total_ips_scanned;
    }

}