CODEWITHSUNDEEP
java
MItch Branting
MItch Branting

Reputation: 613

How to check if an IP address is the local host on a multi-homed system?

For a machine with multiple NIC cards, is there a convenient method in Java that tells whether a given IP address is the current machine or not. e.g.

boolean IsThisMyIpAddress("192.168.220.25");

Upvotes: 41

Views: 32253

Answers (1)

Kevin Brock
Kevin Brock

Reputation: 8944

If you are looking for any IP address that is valid for the local host then you must check for special local host (e.g. 127.0.0.1) addresses as well as the ones assigned to any interfaces. For instance...

public static boolean isThisMyIpAddress(InetAddress addr) {
    // Check if the address is a valid special local or loop back
    if (addr.isAnyLocalAddress() || addr.isLoopbackAddress())
        return true; // Was local sub-net.

    // Check if the Non-local address is defined on any Local-interface.
    try {
        return NetworkInterface.getByInetAddress(addr) != null;
    } catch (SocketException e) {
        return false;
    }
}

With a string, indicating the port, call this with:

boolean isMyDesiredIp = false;
try
{
    isMyDesiredIp = isThisMyIpAddress(InetAddress.getByName("192.168.220.25")); //"localhost" for localhost
}
catch(UnknownHostException unknownHost)
{
    unknownHost.printStackTrace();
}

Upvotes: 73

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