Retrieving IP and mac addresses

Question

I want to get IP Address and MAC address of my pc. I used the following code to do so:

InetAddress ip; try { ip = InetAddress.getLocalHost(); System.out.println("Current IP address : " + ip.getHostAddress()); NetworkInterface network = NetworkInterface.getByInetAddress(ip); byte[] mac = network.getHardwareAddress(); System.out.print("Current MAC address : "); StringBuilder sb = new StringBuilder(); for (int i = 0; i < mac.length; i++) { sb.append(String.format("%02X%s", mac[i], (i < mac.length - 1) ? "-" : "")); } System.out.println(sb.toString()); } catch (UnknownHostException e) { e.printStackTrace(); } catch (SocketException e){ e.printStackTrace(); }

It worked too, but some times the same code prints IP as 127.0.0.1 and doesn't print any mac address. How come?

this code is running on a applet or java app at client or on your server? — tgkprog
– tgkprog, Commented Sep 10, 2013 at 8:59

SJuan76 · Accepted Answer · 2013-09-09 16:26:54Z

127.0.0.1 is the loopback address which always exists (*).

A better way of getting the value would be getting all the network interfaces (http://docs.oracle.com/javase/6/docs/api/java/net/NetworkInterface.html#getNetworkInterfaces()) and filtering out the ones whose IP begins with 127.

(*) Except on windows machines where the network cable is disconnected...

i want to identify client's pc... here i m getting mac address from ip i got InetAddress.getLocalHost().. which is sometimes giving loopback address.... is there any way of gettig mac without ip

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