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Thread: How to Find machines connected to a network

  1. #1
    mmm.. coffee JavaPF's Avatar
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    Post How to Find machines connected to a network

    This code will effectively ping an IP range looking for machines on a network.

    It isn't the fastest method but works none the less.

    import java.io.IOException;
    import java.net.InetAddress;
     
    public class NetworkPing {
     
        /**
         * JavaProgrammingForums.com
         */
        public static void main(String[] args) throws IOException {
     
            InetAddress localhost = InetAddress.getLocalHost();
            // this code assumes IPv4 is used
            byte[] ip = localhost.getAddress();
     
            for (int i = 1; i <= 254; i++)
            {
                ip[3] = (byte)i;
                InetAddress address = InetAddress.getByAddress(ip);
            if (address.isReachable(1000))
            {
                System.out.println(address + " machine is turned on and can be pinged");
            }
            else if (!address.getHostAddress().equals(address.getHostName()))
            {
                System.out.println(address + " machine is known in a DNS lookup");
            }
            else
            {
                System.out.println(address + " the host address and host name are equal, meaning the host name could not be resolved");
            }
            }
     
        }
    }
    Please use [highlight=Java] code [/highlight] tags when posting your code.
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    Hallowed (April 8th, 2011)


  3. #2
    Junior Member friez's Avatar
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    Default Re: How to Find machines connected to a network

    great program sir;
    but will you please explain this part of code
    InetAddress localhost = InetAddress.getLocalHost();
    // this code assumes IPv4 is used
    byte[] ip = localhost.getAddress();

    for (int i = 1; i <= 254; i++)
    {
    ip[3] = (byte)i;
    InetAddress address = InetAddress.getByAddress(ip);
    if (address.isReachable(1000))
    for me. if you don't mind. I'm just novice with Java.
    Java means

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