Java Socket Programming Exception

Question

I'm receiving java socket programming exception. This is a code from the Book "Java Complete reference Oracle"

import java.net.*;
import java.io.*;

public class Whois {
public static void main(String[] args)throws Exception{
    int c;

    Socket s = new Socket("whois.internic.net",43);

    InputStream in = s.getInputStream();
    OutputStream out = s.getOutputStream();

    String str = (args.length == 0 ? "OraclePressBooks.com" : args[0]) + "\n";
    byte buf[] = str.getBytes();


    out.write(buf);


    while((c=in.read())!=-1)
    {
        System.out.println((char)c);
    }
    s.close();
}
}

I'm getting following exception. But Why?

Exception in thread "main" java.net.ConnectException: Connection timed out: connect
at java.net.DualStackPlainSocketImpl.connect0(Native Method)
at java.net.DualStackPlainSocketImpl.socketConnect(Unknown Source)
at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)
at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)
at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
at java.net.PlainSocketImpl.connect(Unknown Source)
at java.net.SocksSocketImpl.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at java.net.Socket.<init>(Unknown Source)
at java.net.Socket.<init>(Unknown Source)
at Whois.main(Whois.java:8)

P.S. I'm using Eclipse Photon. I tried running eclipse "as administrator" and also without it.

I would suggest you attempt a trace route to determine where the connection attempts are being dropped. Unfortunately, as we cannot reproduce this issue, we cannot help you. — Joe C, Jul 15 '18 at 11:51
Okay fine. Can you just tell me what is code snippet is intending to do? Can you explain me what is purpose of this code actually? — Nitish Prajapati, Jul 15 '18 at 12:08
I understand that you got it from a book. The same book should be able to explain it to you. — Joe C, Jul 15 '18 at 12:12
You don't have network connectivity to the target. It is a configuration issue. It has nothing to do with this code. — user207421, Jul 15 '18 at 13:30

score 0 · Answer 1 · answered Jul 15 '18 at 14:05

You do not have network connectivity to remote TCP port 43.

But since you've written that you have "proper network connection" because you are "using WiFi", we may suppose you have at least a web access (through a transparent proxy, or direct connections).

Therefore, you can simply use a Whois web service to access Whois databases. Some registrars offer a RWS-DNRD endpoint, that is a RESTful Web Service for Domain Name Registration Data (https://tools.ietf.org/id/draft-sheng-weirds-icann-rws-dnrd-01.html). You will find many examples of RESTful clients, for instance here: https://www.javacodegeeks.com/2012/09/simple-rest-client-in-java.html

In your case, you want to access the Internic database, so you can simply query their web form, using a GET request, like that (Java 9):

URL u = new URL("https://reports.internic.net/cgi/whois?whois_nic=OraclePressBooks.com&type=domain");
try (InputStream in = u.openStream()) {
    return new String(in.readAllBytes(), StandardCharsets.UTF_8);
}

Java Socket Programming Exception

1 Answers1