Get interface's hardware address (MAC address)

This example gets a list of interfaces then iterates through the list. For each interface it acquires MAC address, formats it and prints it out. The example skips any interfaces that do not have a MAC address assigned such as loop interfaces non datalink interfaces.

Source code: GetInterfaceHardwareAddress.java

package org.jnetpcap.examples;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.jnetpcap.Pcap;
import org.jnetpcap.PcapIf;

public class GetInterfaceHardwareAddress {

  public static void main(String[] args) throws IOException {

    List<PcapIf> alldevs = new ArrayList<PcapIf>(); // Will be filled with NICs
    StringBuilder errbuf = new StringBuilder(); // For any error msgs

    /***************************************************************************
     * First get a list of devices on this system
     **************************************************************************/
    int r = Pcap.findAllDevs(alldevs, errbuf);
    if (r == Pcap.NOT_OK || alldevs.isEmpty()) {
      System.err.printf("Can't read list of devices, error is %s", errbuf
        .toString());
      return;
    }

    /***************************************************************************
     * Second iterate through all the interface and get the HW addresses
     **************************************************************************/
    for (final PcapIf i : alldevs) {
      final byte[] mac = i.getHardwareAddress();
      if (mac == null) {
        continue; // Interface doesn't have a hardware address
      }
      System.out.printf("%s=%s\n", i.getName(), asString(mac));
    }
  }

  private static String asString(final byte[] mac) {
    final StringBuilder buf = new StringBuilder();
    for (byte b : mac) {
      if (buf.length() != 0) {
        buf.append(':');
      }
      if (b >= 0 && b < 16) {
        buf.append('0');
      }
      buf.append(Integer.toHexString((b < 0) ? b + 256 : b).toUpperCase());
    }

    return buf.toString();
  }
}