Methodo que faz ping

import java.io.*;  
import java.net.*;  
  
public class Ping {  
  static final int DEFAULT_PORT = 7;  
  static final int UDP_HEADER = 20 + 8;  
  static final int BACKSPACE = 8;  
  
  public static void main (String[] args) throws IOException {  
    parseArgs (args);  
    init ();  
    for (int i = 0; (i < count) || (count == 0); ++ i) {  
      long past = System.currentTimeMillis ();  
      ping (i, past);  
      try {  
        pong (i, past);  
      } catch (InterruptedIOException ignored) {  
      }  
    }  
    socket.close ();  
    printStats ();  
  }  
  
  static String host = null;  
  static int port, count = 32, delay = 1000, size = 64;  
  static boolean flood = false;  
  
  static void parseArgs (String args[]) {  
    for (int i = 0; i < args.length; ++ i) {  
      if (args[i].startsWith ("-")) {  
        if (args[i].equals ("-c") && (i < args.length - 1))  
          count = Integer.parseInt (args[++ i]);  
        else if (args[i].equals ("-i") && (i < args.length - 1))  
          delay = Math.max (10, Integer.parseInt (args[++ i]));  
        else if (args[i].equals ("-s") && (i < args.length - 1))  
          size = Integer.parseInt (args[++ i]);  
        else if (args[i].equals ("-f"))  
          flood = true;  
        else  
          syntaxError ();  
      } else {  
        if (host != null)  
          syntaxError ();  
        int colon = args[i].indexOf (":");  
        host = (colon > -1) ? args[i].substring (0, colon) : args[i];  
        port = ((colon > -1) && (colon < args[i].length () - 1)) ?  
          Integer.parseInt (args[i].substring (colon + 1)) : DEFAULT_PORT;  
      }  
    }  
    if (host == null)  
      syntaxError ();  
  }  
  
  static void syntaxError () {  
    throw new IllegalArgumentException  
      ("Ping [-c count] [-i wait] [-s packetsize] [-f]<hostname>[:<port>]");  
  }  
  
  static DatagramSocket socket;  
  static byte[] outBuffer, inBuffer;  
  static DatagramPacket outPacket, inPacket;  
  
  static void init () throws IOException {  
    socket = new DatagramSocket ();  
    outBuffer = new byte[Math.max (12, size - UDP_HEADER)];  
    outPacket = new DatagramPacket (outBuffer, outBuffer.length,  
                                    InetAddress.getByName (host), port);  
    inBuffer = new byte[outBuffer.length];  
    inPacket = new DatagramPacket (inBuffer, inBuffer.length);  
  }  
  
  static int sent = 0;  
  
  static void ping (int seq, long past) throws IOException {  
    writeInt (seq, outBuffer, 0);  
    writeLong (past, outBuffer, 4);  
    socket.send (outPacket);  
    ++ sent;  
    if (flood) {  
      System.out.write ('.');  
      System.out.flush ();  
    }  
  }  
  
  static final void writeInt (int datum, byte[] dst, int offset) {  
    dst[offset] = (byte) (datum >> 24);  
    dst[offset + 1] = (byte) (datum >> 16);  
    dst[offset + 2] = (byte) (datum >> 8);  
    dst[offset + 3] = (byte) datum;  
  }  
  
  static final void writeLong (long datum, byte[] dst, int offset) {  
    writeInt ((int) (datum >> 32), dst, offset);  
    writeInt ((int) datum, dst, offset + 4);  
  }  
  
  static int received = 0;  
  
  static void pong (int seq, long past) throws IOException {  
    long present = System.currentTimeMillis ();  
    int tmpRTT = (maxRTT == 0) ? 500 : (int) maxRTT * 2;  
    int wait = Math.max (delay, (seq == count - 1) ? tmpRTT : 0);  
    do {  
      socket.setSoTimeout (Math.max (1, wait - (int) (present - past)));  
      socket.receive (inPacket);  
      ++ received;  
      present = System.currentTimeMillis ();  
      processPong (present);  
    } while ((present - past < wait) && !flood);  
  }  
  
  static long minRTT = 100000, maxRTT = 0, totRTT = 0;  
  
  static void processPong (long present) {  
    int seq = readInt (inBuffer, 0);  
    long when = readLong (inBuffer, 4);  
    long rtt = present - when;  
    if (!flood) {  
      System.out.println  
        ((inPacket.getLength () + UDP_HEADER) +  
         " bytes from " + inPacket.getAddress ().getHostName () +  
         ": seq no " + seq + " time=" + rtt + " ms");  
    } else {  
      System.out.write (BACKSPACE);  
      System.out.flush ();  
    }  
    if (rtt < minRTT) minRTT = rtt;  
    if (rtt > maxRTT) maxRTT = rtt;  
    totRTT += rtt;  
  }  
  
  static final int readInt (byte[] src, int offset) {  
    return (src[offset] << 24) | ((src[offset + 1] & 0xff) << 16) |  
      ((src[offset + 2] & 0xff) << 8) | (src[offset + 3] & 0xff);  
  }  
  
  static final long readLong (byte[] src, int offset) {  
    return ((long) readInt (src, offset) << 32) |  
      ((long) readInt (src, offset + 4) & 0xffffffffL);  
  }  
  
  static void printStats () {  
    System.out.println  
      (sent + " packets transmitted, " + received + " packets received, " +  
       (100 * (sent - received) / sent) + "% packet loss");  
    if (received > 0)  
      System.out.println ("round-trip min/avg/max = " + minRTT + '/' +  
                          ((float) totRTT / received) + '/' + maxRTT + " ms");  
  }  
}

InetAddress.getByName(host).isReachable(timeOut)