Dmitry Dmitry - 7 months ago 33
Java Question

Converting CIDR address to subnet mask and network address

Given a CIDR address, e.g.

192.168.10.0/24



  • How to determine mask length? (
    24
    )

  • How to determine mask address? (
    255.255.255.0
    )

  • How to determine network address? (
    192.168.10.0
    )


Answer

It is covered by apache utils.

See this URL: http://commons.apache.org/proper/commons-net/apidocs/org/apache/commons/net/util/SubnetUtils.html

String subnet = "192.168.0.3/31";
SubnetUtils utils = new SubnetUtils(subnet);

utils.getInfo().isInRange(address)

Note: For use w/ /32 CIDR subnets, for exemple, one needs to add the following declaration :

utils.setInclusiveHostCount(true);