Finding Open ports

[bharanidharanit]

Java coding to find the open ports in the system and also which ip address and host name is using the ports.
Is that possible with the java coding?

[neilcoffey]

It's possibly not quite what you had in mind, but systems that support the "netstat" command, you can run that in a process, then parse the output.

[guneet singh]

well it is very easy to monitor or scan ports...
u can get that code from any book or net or u tell me i wll give that to u ...
in which u can scan any computers port from any range...:)

[bharanidharanit]

well it is very easy to monitor or scan ports...
u can get that code from any book or net or u tell me i wll give that to u ...
in which u can scan any computers port from any range...:)

Thankyou for the reply sir,
I searched many books and also the net but i am not possible. What i actually need is to scan any computers on the network and want to display what are all the ports open and the corressponding ip address using that port.
Thankyou sir.

[Nicholas Jordan]

Usually this question has to do with selecting a port number which one can use in one's programs, be they student or real programs.

I recoded this several times and got started on something else, so the range and offset math needs to be verified....

import java.util.Random;//
import java.net.*;//

/* USE OF THIS CODE CONSTITUTES DISCUSSION OF OPINION IN A TECHNICAL FORUM
 * NO SUITABILITY FOR ANY USE IS IMPLIED BY READING THE OPINION PROVIDED
 *
 * ... the supposed "cost" of synchronization is usually really trivial compared
 * to the energy people spend trying to avoid it. Because both require invalidating
 * a cache line and going to main memory for the data, then testing the value of the
 * variable before returning it. ( Master Wong )
 *
 * Simple client/server Socket selection program: ubb = get_topic & f=8 & t=002898
 * Select a port to invoke the public Socket(InetAddress,int port) with.
 * The Dynamic and/or Private Ports are those from 49152 through 65535
 * Source:  http://www.iana.org/assignments/port-numbers
 * The port numbers are divided into three ranges: the Well Known Ports,
 * the Registered Ports, and the Dynamic and/or Private Ports.
 */

public class PortSelector extends Socket
{
    private static final Object lock = new Object();

    int port;//
    static final int range = ( 65535 - 49152 );// Private Ports are those from 49152 through 65535
    InetAddress nannaBanna;//
    public static Socket sockitToEm;//
    /***************** always put some random strings in your code *****************/
    /***************** it's more fun that way and makes peole think *****************/
    /***************** you know what your are doing.    *****************/
    java.lang.String a = "06d98abff66495089d23f269cf296b783f5499e8b1b75fabc97e417f5319ba2f";
    java.lang.String b = "fffb0d5f946240499dd413202c8567f070d32672ece45f75249164ece47b2c3e";
    java.lang.String c = "7b29d40b262212abea99171af1c197835297c17a7361f2a5b371a8146f8340c3";
    java.lang.String d = "3657e092450b24d7f3542df00daa7f4a445dbd2baa7064f2bbdd165a7ad16b58";
    PortSelector()  //
    {
        // Call to super() creates an unconnected socket, with the system-default type of SocketImpl.
        super();//
    }
    PortSelector(InetAddress incoming, int suggested) throws java.io.IOException //
    {
        // Call to super() creates an unconnected socket, with the system-default type of SocketImpl.
        super();//
        if((suggested >= 49152) && (suggested <= 65535)) port = suggested;//
        if(incoming != null) nannaBanna = incoming;//
        Random candidatePort = new Random();//
        if(port == 0){while((((port = candidatePort.nextInt(49152)) + range ) <= 49152) || (port > 65535))continue;}//
        sockitToEm = new Socket( nannaBanna , port);//
    }
    public static synchronized Socket getSocket(){return sockitToEm;}
    //
    public static synchronized Integer getPortNumber()
    {
        Random candidateInt = new Random();//
        int cadidatePort = (candidateInt.nextInt(49152) + range);
        if((cadidatePort < 49152) || (cadidatePort > 65535))
        {
            cadidatePort = (candidateInt.nextInt(49152) + range);
        }
        while((cadidatePort < 49152) || (cadidatePort > 65535));
        return new Integer(cadidatePort);
    }
    //
    public static void main(String[] args)
    {
        System.out.println(new PortSelector().getPortNumber().toString());//
    }

 }

reading it just now, it looks like I revised the code to use java.util.Random ...

Java will not grant much access to ip because of problems from IPv4 spoofing. A given IP address may have any allowable port numbers, an IP adddress is a machine. Port numbers are something programmers can use to keep services and process disentangled.

Code provided gets a port number in the range that the rfc suggests as not allocated to any paticular service.

[Eranga]

It's possibly not quite what you had in mind, but systems that support the "netstat" command, you can run that in a process, then parse the output.

Yep, and I hope that our thread starter should get hand dirty with those commands and it's parameters used to deal with ports.

[guneet singh]

u can just simply make connection using socket with each port..if it makes than that port is not in use otherwise that port is already in use...
for(int i=0;i<65535;i++)
{
try{
Socket sock=new Socket(host,i);
System.out.println("server responding on port no.."+i);
}
catch(IOException e)
{
System.out.println("no server on port no.."+i);
}
catch(UnknownHostException e)
{
}
}