Does anyone know a java component to check if IP address is from particular network/netmask?

I need to determine if given IP address is from some special network i must authenticate automatically.

From stackoverflow

• You can use the java network interface like so:

  Enumeration<NetworkInterface> nets = NetworkInterface.getNetworkInterfaces();
      for (NetworkInterface netint : Collections.list(nets)){
          Enumeration<InetAddress> inetAddresses = netint.getInetAddresses();
          for (InetAddress inetAddress : Collections.list(inetAddresses)) {
              //check if inetAddress is from particular address
          }
      }
  

  Eddie : I don't think that miceuz is asking to see if a given IP address represents a local network interface, so this probably won't help.

• Jakarta Commons Net has org.apache.commons.net.util.SubnetUtils that appears to satisfy your needs. It looks like you do something like this:

  SubnetInfo subnet = (new SubnetUtils("10.10.10.0", "255.255.255.128")).getInfo();
  boolean test = subnet.isInRange("10.10.10.10");
  

  Note, as carson points out, that Jakarta Commons Net has a bug that prevents it from giving the correct answer in some cases. Carson suggests using the SVN version to avoid this bug.

  carson : Be careful using this. There is a bug that will keep it from working correctly. You may want to pull it out of SVN. http://mail-archives.apache.org/mod_mbox/commons-issues/200902.mbox/%3C2039253761.1233796319684.JavaMail.jira@brutus%3E

  Eddie : @carson: Thanks for the warning. I edited my answer to include this information.

• You can also try

  boolean inSubnet = (ip & netmask) == (subnet & netmask);
  

  or shorter

  boolean inSubnet = (ip ^ subnet) & netmask == 0;