how to detect broadcast ip in java

 How to detect Denial of Service attack

The project need jpcap.

import jpcap.*;
import jpcap.packet.ARPPacket;
import jpcap.packet.Packet;

class Tcpdump implements PacketReceiver {
public void receivePacket(Packet packet) {
if (packet instanceof ARPPacket) {
System.out.println(packet);
ARPPacket arp=(ARPPacket)packet;
// System.out.println(arp.hardtype=ARPPacket.HARDTYPE_ETHER);
// System.out.println(arp.prototype=ARPPacket.PROTOTYPE_IP);
// System.out.println(arp.prototype=ARPPacket.PROTOTYPE_IP);
// System.out.println(arp.operation=ARPPacket.ARP_REQUEST);
System.out.println("sender hardware address ----->" +arp.getSenderHardwareAddress());
System.out.println("Sender protocol address ----->"+arp.getSenderProtocolAddress());
System.out.println("target hardware address ----->"+arp.getTargetHardwareAddress());
System.out.println("target protocol address ----->"+arp.getTargetProtocolAddress());
System.out.println(" arp reply (short) ----->"+ arp.ARP_REPLY);
System.out.println(" arp request (short) ----->"+arp.ARP_REQUEST);
// System.out.println(" arp caplen (int) ----->"+arp.caplen);
// System.out.println(" arp hardtype (short) ----->"+arp.hardtype);
// System.out.println(" arp hlen (short) ------>"+arp.hlen);
// System.out.println(" arp packetlength (int) ------>"+arp.len);
// System.out.println(" arp operation (short) ----->"+arp.operation);
// System.out.println(" arp plen (short) ------>"+arp.plen);
// System.out.println(" arp prototype (short) ------>"+arp.prototype);
// System.out.println(" arp second (long) ------>"+arp.sec);
// System.out.println(" arp usec (long) ------>"+arp.usec);
// System.out.println(" arp hashcode (int) ------>"+arp.hashCode());
// System.out.println(" arp to string ------>"+ arp.toString());
// System.out.println(" arp hardtype ether(short) ------>"+arp.HARDTYPE_ETHER);
// System.out.println(" arp frame relay (short) ------>"+arp.HARDTYPE_FRAMERELAY);
// System.out.println(" arp hardtype ieee802(short) ---->"+arp.HARDTYPE_IEEE802);
// System.out.println(" arp inv reply (short)----->"+arp.INV_REPLY);
// System.out.println(" arp inv request (short)----->"+arp.INV_REQUEST);
// System.out.println(" arp prototype ip (short) ---->"+arp.PROTOTYPE_IP);
// System.out.println(" arp rarp reply (short)----->"+arp.RARP_REPLY);
// System.out.println(" arp rarp request (short)----->"+ arp.RARP_REQUEST);
// System.out.println(" arp data (byte[])---->"+arp.data);
// System.out.println(" arp datalink ( datalink)----->"+arp.datalink);
// System.out.println(" arp header (byte[]) ----->"+arp.header);
// System.out.println(" arp sender hardaddress (byte[])---->"+arp.sender_hardaddr);
// System.out.println(" arp sender proto address (byte[]) ---->"+arp.sender_protoaddr);
// System.out.println(" arp target hard address (byte[])---->"+arp.target_hardaddr);
// System.out.println(" arp target proto address (byte[])----->"+arp.target_protoaddr);
// System.out.println(" arp get class (class) ----->"+arp.getClass());
// System.out.println(" arp end of file ---->"+arp.EOF);
System.out.println(" ******************************************************* ");
String s=arp.getSenderProtocolAddress().toString();
System.out.println("string" +s);
if(s.endsWith("1"))
{
int l=s.length();
String sub=s.substring(1,l);
System.out.println(" sub string(ipaddr)"+sub);
}

System.out.println(" ******************************************************* ");



// arp.hlen=6;
// arp.plen=4;

}
}

public static void main(String[] args) throws Exception {
NetworkInterface[] devices = JpcapCaptor.getDeviceList();
// if(args.length<1){
// System.out.println("usage: java Tcpdump