How to get remote machines mac addresses java

Question

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Query ARP cache to get MAC ID

I need to get the mac addresses of all the remote machines connected to my home network. i can read the mac address of my own machine using this code below but i don't know how to get the mac addresses of other machines on my network. or is it possible or not.

import java.net.InetAddress;
import java.net.NetworkInterface;
class Test {
public static void main(String[] args) throws Exception {
InetAddress address = InetAddress.getLocalHost();

NetworkInterface ni = NetworkInterface.getByInetAddress(address);
byte[] mac = ni.getHardwareAddress();

for (int i = 0; i < mac.length; i++) {
  System.out.format("%02X%s", mac[i], (i < mac.length - 1) ? "-" : "");
}
}
}

output (MyComputer's 6byte mac address)
30-60-77-12-cd-99

For what purpose? There's nothing useful you can do with a MAC address in Java except display it. — user207421, Dec 28 '12 at 09:02

score 1 · Accepted Answer · answered Dec 28 '12 at 02:46

How to get remote machines mac addresses

You cannot do that - not in the general case. MAC addresses are only available for machines in the same physical network segment. Those machines communicate directly with each other using the ARP protocol to "translate" IP addresses to physical (MAC) addresses.

As soon as an IP router or any other Layer-3 device is crossed, any MAC information is generally lost.

Bottom line: you cannot get the MAC address of a remote node over the Internet - you cannot even do that in any moderately sized private network, as implemented in e.g. most medium to large companies.

This is also why wake-on-LAN packets need to come from a machine in the same physical net segment. — Thorbjørn Ravn Andersen, Jul 20 '13 at 06:50

How to get remote machines mac addresses java

1 Answers1