private NetworkInterface getDevice() throws Exception {
devices = JpcapCaptor.getDeviceList();
device = devices[0];
jpcap = JpcapCaptor.openDevice(device, 2000, false, 10000);
jpcap.setFilter("ip", true);
// sender = jpcap.getJpcapSenderInstance();
jpcap.loopPacket(-1, new PacketReceiverImpl());
return device;
}
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(bip, bif)) {
device = d;
break loop;
}
}
}
if (device == null) throw new IllegalArgumentException(ip + " is not a local address");
// open Jpcap
JpcapCaptor captor = JpcapCaptor.openDevice(device, 2000, false, 3000);
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_protoaddr, srcip.getAddress())) {
return p.sender_hardaddr;
}
}
}
