Fwd: InetAddress.getAllByName()/getByName() fails to resolve IPv6 via ssh

[Kurchi Hazra]

Forwarding to net-dev

Hi Charis,

     I tried to recreate this,  I ran your code remotely (from both 
Linux and Windows onto a Linux machine) but could not
get an UnkownHostException if the code works without an exception when 
run locally on a machine.
Can you be more specific about the operating systems running on both 
systems?

Thanks,
Kurchi


-------- Original Message --------
Subject: 	InetAddress.getAllByName()/getByName() fails to resolve IPv6 
via ssh
Date: 	Mon, 17 Dec 2012 21:55:40 -0800 (PST)
From: 	charis <charis.charitsis at oracle.com>
To: 	nio-dev at openjdk.java.net



I am facing the following issue:
Say there is a simple standlone code Test.java which just calls
InetAddress.getAllByName() :

*
import java.net.Inet4Address;
import java.net.Inet6Address;
import java.net.InetAddress;
import java.net.UnknownHostException;


public class TestNameResolution {
     public static void main(String args[])  {
         String name = args[0];
         System.out.println("Trying to resolve name \"" + name + "\" to IP
addresses");
         try {
             InetAddress[] addresses = InetAddress.getAllByName(name);

             for (int i = 0; i<  addresses.length; i++) {
                 if (addresses[i] instanceof Inet4Address) {
                      System.out.println("IPv4 address -->" +
addresses[i].getHostAddress());
                 }
                 else if (addresses[i] instanceof Inet6Address) {
                      System.out.println("IPv6 address -->" +
addresses[i].getHostAddress());
                 }
             }
         }
         catch (UnknownHostException uhe) {
             System.out.println("Cannot resolve name \"" + name + "\"");
         }
     }
}
*

I run this via a simple single-line script 'run':
*
java -classpath<absolute path of TestNameResolution.class>
TestNameResolution<ipv6-name-to-resolve>
*

When try this locally it resolves the name to its IPv6 address as expected.
However, when from a different machine to execute this via ssh (i.e.,  ssh
<my machine name>  <path to 'run' script>) I often get the following output:

/
Trying to resolve name "<ipv6-name-to-resolve>" to IP addresses
Cannot resolve name "<ipv6-name-to-resolve>"
java.net.UnknownHostException:<ipv6-name-to-resolve>
at java.net.Inet4AddressImpl.lookupAllHostAddr(Native Method)
at java.net.InetAddress$1.lookupAllHostAddr(InetAddress.java:849)
at
java.net.InetAddress.getAddressFromNameService(InetAddress.java:1202)
at java.net.InetAddress.getAllByName0(InetAddress.java:1153)
at java.net.InetAddress.getAllByName(InetAddress.java:1083)
at java.net.InetAddress.getAllByName(InetAddress.java:1019)
at TestNameResolution.main(TestNameResolution.java:14
/

Note:
- I tried the java command that invokes the standalone also with i)
'-Djava.net.preferIPv6Stack=true' , ii) and
'-Djava.net.preferIPv6Addresses=true' and iii) with both of them at the same
time.
Still, the output is the same
- The same standalone succeeds in resolving a name which maps to IPv4 giving
the same (correct) output on the local and the remote node (where the ssh is
initiated)

Java environment details:
$ java -version
java version "1.6.0_37"
Java(TM) SE Runtime Environment (build 1.6.0_37-b06)


Is there any known issue with IPv6 name resolution via ssh? Any ideas what
may be causing this?



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