How to Determine Internet Network Interface in Java

Question

How do you determine which network interface is connected to the internet using Java? For example, I run

InetAddress.getLocalHost().getHostAddress();
         


        

Answer 1

I was having the same problem, and came up with this solution (not as thorough as the answer, but I needed something that didn't try to connect to the internet.

Based on known OUI for mac addresses: http://standards-oui.ieee.org/oui.txt

I made a quick check (could be optimized with binary logic)

private static boolean isVmwareMac(byte[] mac) {
    byte invalidMacs[][] = {
            {0x00, 0x05, 0x69},             //VMWare
            {0x00, 0x1C, 0x14},             //VMWare
            {0x00, 0x0C, 0x29},             //VMWare
            {0x00, 0x50, 0x56}              //VMWare
    };

    for (byte[] invalid: invalidMacs){
        if (invalid[0] == mac[0] && invalid[1] == mac[1] && invalid[2] == mac[2])
            return true;
    }

    return false;
}