Try to extract a hardware MAC address from a given IP address using the ARP cache (/proc/net/arp). We assume that the file has this structure: IP address HW type Flags HW address Mask Device 192.168.18.11 0x1 0x2 00:04:20:06:55:1a * eth0 192.168.18.36 0x1 0x2 00:22:43:ab:2a:5b * eth0 - Android Wifi

Android examples for Wifi:Wifi Address

  1. HOME
  2. Android
  3. Wifi
  4. Wifi Address

Description

Try to extract a hardware MAC address from a given IP address using the ARP cache (/proc/net/arp). We assume that the file has this structure: IP address HW type Flags HW address Mask Device 192.168.18.11 0x1 0x2 00:04:20:06:55:1a * eth0 192.168.18.36 0x1 0x2 00:22:43:ab:2a:5b * eth0

Demo Code


//package com.java2s;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

public class Main {
    /**/*from www .  j  a va  2s .  c  om*/
     * Try to extract a hardware MAC address from a given IP address using the
     * ARP cache (/proc/net/arp).<br>
     * <br>
     * We assume that the file has this structure:<br>
     * <br>
     * IP address HW type Flags HW address Mask Device 192.168.18.11 0x1 0x2
     * 00:04:20:06:55:1a * eth0 192.168.18.36 0x1 0x2 00:22:43:ab:2a:5b * eth0
     *
     * @param ip
     * @return the MAC from the ARP cache
     */
    public static String getMacFromArpCache(String ip) {
        if (ip == null)
            return null;
        BufferedReader br = null;
        try {
            br = new BufferedReader(new FileReader("/proc/net/arp"));
            String line;
            while ((line = br.readLine()) != null) {
                String[] splitted = line.split(" +");
                if (splitted != null && splitted.length >= 4
                        && ip.equals(splitted[0])) {
                    // Basic sanity check
                    String mac = splitted[3];
                    if (mac.matches("..:..:..:..:..:..")) {
                        return mac;
                    } else {
                        return null;
                    }
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                br.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return null;
    }

    public static String getMacFromArpCache(int ip) {
        byte[] i = new byte[4];
        i[0] = (byte) ((byte) ip & 0xff);
        i[1] = (byte) ((byte) (ip >> 8) & 0xff);
        i[2] = (byte) ((byte) (ip >> 16) & 0xff);
        i[3] = (byte) ((byte) (ip >> 24) & 0xff);
        String ipString = String.format("%d.%d.%d.%d", i[0], i[1], i[2],
                i[3]);
        return getMacFromArpCache(ipString);
    }
}

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