Java check if IPv4 or IPv6 address is in a given subnet

Question

How can I check if an IP address is in a given subnet? I was able to do this by using Apache Commons SubnetUtils (SubnetUtils.SubnetInfo.isInRange) but it does not support IPv6 yet.

Solution 1

edazdarevic's CIDRUtils supports both IPv4 and IPv6. The example does not mention boolean isInRange(String ipAddress), but it is implemented!

Another option is java-ipv6, but it does not support IPv4 and requires JDK7.

Solution 2

Use spring-security-web's IpAddressMatcher. Unlike Apache Commons Net, it supports both ipv4 and ipv6.

import org.springframework.security.web.util.matcher.IpAddressMatcher;
...

private void checkIpMatch() {
    matches("192.168.2.1", "192.168.2.1"); // true
    matches("192.168.2.1", "192.168.2.0/32"); // false
    matches("192.168.2.5", "192.168.2.0/24"); // true
    matches("92.168.2.1", "fe80:0:0:0:0:0:c0a8:1/120"); // false
    matches("fe80:0:0:0:0:0:c0a8:11", "fe80:0:0:0:0:0:c0a8:1/120"); // true
    matches("fe80:0:0:0:0:0:c0a8:11", "fe80:0:0:0:0:0:c0a8:1/128"); // false
    matches("fe80:0:0:0:0:0:c0a8:11", "192.168.2.0/32"); // false
}

private boolean matches(String ip, String subnet) {
    IpAddressMatcher ipAddressMatcher = new IpAddressMatcher(subnet);
    return ipAddressMatcher.matches(ip);
}

Remarks

If you're not willing to include Spring in your project, check out my other answer, here.

Solution 3

commons-ip-math provides support for both IPv4 and IPv6 addresses. Here is how you can check if an IP address is in a given subnet:

Ipv4Range.parse("192.168.0.0/24").contains(Ipv4.parse("10.0.0.1")) 
// false

Ipv6Range.parse("2001:db8::/32").contains(Ipv6.parse("2001:db8::4"))
// true

(disclaimer, I'm one of the maintainers of commons-ip-math)

Solution 4

The IPAddress Java library supports both IPv4 and IPv6 in a polymorphic manner and supports subnets, including methods that check for containment of an address or subnet in a containing subnet. The javadoc is available at the link. Disclaimer: I am the project manager of that library.

Example code:

contains("10.10.20.0/30", "10.10.20.3");
contains("10.10.20.0/30", "10.10.20.5");
contains("1::/64", "1::1");
contains("1::/64", "2::1");
contains("1::3-4:5-6", "1::4:5");       
contains("1-2::/64", "2::");
contains("bla", "foo");

static void contains(String network, String address) {
    IPAddressString one = new IPAddressString(network);
    IPAddressString two = new IPAddressString(address);
    System.out.println(one +  " contains " + two + " " + one.contains(two));
}

Output:

10.10.20.0/30 contains 10.10.20.3 true
10.10.20.0/30 contains 10.10.20.5 false
1::/64 contains 1::1 true
1::/64 contains 2::1 false
1::3-4:5-6 contains 1::4:5 true
1-2::/64 contains 2:: true
bla contains foo false

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Comments

[Vadzim]

Commons Net feature request to vote for: issues.apache.org/jira/browse/NET-405