How to enumerate IP addresses of all enabled NIC cards from Java?

Question

Short of parsing the output of ipconfig, does anyone have a 100% pure java way of doing this?

Answer 1

This is pretty easy:

try {   InetAddress localhost = InetAddress.getLocalHost();   LOG.info(" IP Addr: " + localhost.getHostAddress());   // Just in case this host has multiple IP addresses....   InetAddress[] allMyIps = InetAddress.getAllByName(localhost.getCanonicalHostName());   if (allMyIps != null && allMyIps.length > 1) {     LOG.info(" Full list of IP addresses:");     for (int i = 0; i < allMyIps.length; i++) {       LOG.info("    " + allMyIps[i]);     }   } } catch (UnknownHostException e) {   LOG.info(" (error retrieving server host name)"); }  try {   LOG.info("Full list of Network Interfaces:");   for (Enumeration<NetworkInterface> en = NetworkInterface.getNetworkInterfaces(); en.hasMoreElements();) {     NetworkInterface intf = en.nextElement();     LOG.info("    " + intf.getName() + " " + intf.getDisplayName());     for (Enumeration<InetAddress> enumIpAddr = intf.getInetAddresses(); enumIpAddr.hasMoreElements(); ) {       LOG.info("        " + enumIpAddr.nextElement().toString());     }   } } catch (SocketException e) {   LOG.info(" (error retrieving network interface list)"); } 

Answer 2

Some of this will only work in JDK 1.6 and above (one of the methods was added in that release.)

List<InetAddress> addrList = new ArrayList<InetAddress>(); for(Enumeration<NetworkInterface> eni = NetworkInterface.getNetworkInterfaces(); eni.hasMoreElements(); ) {    final NetworkInterface ifc = eni.nextElement();    if(ifc.isUp()) {       for(Enumeration<InetAddress> ena = ifc.getInetAddresses(); ena.hasMoreElements(); ) {         addrList.add(ena.nextElement());       }    } } 

Prior to 1.6, it's a bit more difficult - isUp() isn't supported until then.

FWIW: The Javadocs note that this is the correct approach for getting all of the IP addresses for a node:

NOTE: can use getNetworkInterfaces()+getInetAddresses() to obtain all IP addresses for this node