import?java.net.Inet4Address;
import?java.net.InetAddress;
import?java.util.Arrays;

import?jpcap.*;
import?jpcap.packet.*;

public?class?ARP?{
	public?static?byte[]?arp（InetAddress?ip）?throws?java.io.IOException{
		//find?network?interface
		NetworkInterface[]?devices=JpcapCaptor.getDeviceList（）;
		NetworkInterface?device=null;

loop:	for（NetworkInterface?d:devices）{
			for（NetworkInterfaceAddress?addr:d.addresses）{
				if（!（addr.address?instanceof?Inet4Address））?continue;
				byte[]?bip=ip.getAddress（）;
				byte[]?subnet=addr.subnet.getAddress（）;
				byte[]?bif=addr.address.getAddress（）;
				for（int?i=0;i<4;i++）{
					bip[i]=（byte）（bip[i]&subnet[i]）;
					bif[i]=（byte）（bif[i]&subnet[i]）;
				}
				if（Arrays.equals（bipbif））{
					device=d;
					break?loop;
				}
			}
		}
		
		if（device==null）
			throw?new?IllegalArgumentException（ip+“?is?not?a?local?address“）;
		
		//open?Jpcap
		JpcapCaptor?captor=JpcapCaptor.openDevice（device2000false3000）;
		captor.setFilter（“arp“true）;
		JpcapSender?sender=captor.getJpcapSenderInstance（）;
		
		InetAddress?srcip=null;
		for（NetworkInterfaceAddress?addr:device.addresses）
			if（addr.address?instanceof?Inet4Address）{
				srcip=addr.address;
				break;
			}

		byte[]?broadcast=new?byte[]{（byte）255（byte）255（byte）255（byte）255（byte）255（byte）255};
		ARPPacket?arp=new?ARPPacket（）;
		arp.hardtype=ARPPacket.HARDTYPE_ETHER;
		arp.prototype=ARPPacket.PROTOTYPE_IP;
		arp.operation=ARPPacket.ARP_REQUEST;
		arp.hlen=6;
		arp.plen=4;
		arp.sender_hardaddr=device.mac_address;
		arp.sender_protoaddr=srcip.getAddress（）;
		arp.target_hardaddr=broadcast;
		arp.target_protoaddr=ip.getAddress（）;
		
		EthernetPacket?ether=new?EthernetPacket（）;
		ether.frametype=EthernetPacket.ETHERTYPE_ARP;
		ether.src_mac=device.mac_address;
		ether.dst_mac=broadcast;
		arp.datalink=ether;
		
		sender.sendPacket（arp）;
		
		while（true）{
			ARPPacket?p=（ARPPacket）captor.getPacket（）;
			if（p==null）{
				throw?new?IllegalArgumentException（ip+“?is?not?a?local?address“）;
			}
			if（Arrays.equals（p.target_protoaddrsrcip.getAddress（）））{
				return?p.sender_hardaddr;
			}
		}
	}
		
	public?static?void?main（String[]?args）?throws?Exception{
		if（args.length<1）{
			System.out.println（“Usage:?java?ARP?“）;
		}else{
			byte[]?mac=ARP.arp（InetAddress.getByName（args[0]））;
			for?（byte?b?:?mac）
				System.out.print（Integer.toHexString（b&0xff）?+?“:“）;
			System.out.println（）;
			System.exit（0）;
		}
	}
}