For the record, here's the solution.
yum install nss-mdns
Now, this is an x86_64 machine, and the 64-bit version of the library
was already installed, but not the 32 bit version. The installation of
the 32 bit version was the fix.
Evidently JVM is running in 32 bit.
As to why the 32 bit library was not installed, I don't know.
The yum.log shows only the 64 bit version being installed, until I installed
the 32 bit one by hand.
Can anybody shed more light on this?
Cheers!
On 2.11.10, Steve White wrote:
> Hi again,
>
> I just came across a huge clue. A friend had me look again at the java.net
> properties. This one makes the test program work:
> -Djava.net.preferIPv4Stack=true
>
> Now, as to why suddenly Java was preferring the IPv6 stack, I have no idea.
>
> On 2.11.10, Steve White wrote:
> > Hi,
> >
> > A Java networking problem has arisen very recently on one of our servers,
> > an Opeteron with Scientific Linux 5.5, running the distro Java without
> > problems--until a week or so ago.
> >
> > The effect is that all Java apps have become unable to do DNS host name
> > resolution, and throw an UnknownHostException. However nothing seems
> > otherwise amiss with networking on this machine. All non-Java programs
> > resolve outside host names fine.
> >
> > I wrote a small test program, attached. It works fine on other machines
> > here. Fails on the server, with an IP address. But if I give it a valid
> > IP number, or the name of the server itself, it succeeds.
> >
> > I have done security updates fairly regularly; this may have something to
> > do with the problem, but I really don't know for sure.
> >
> > Also tried:
> >
> > * Cut the hosts file down to the bare minimum, and also the resolv.conf
> > file and re-started networking. No improvement.
> >
> > * Logged in as various users. All show the same problem.
> >
> > * Cut down and exported all related environment variables to bare minimum
> > (JAVA_HOME, PATH, *LIBRARY_PATH, etc),
> > No effect.
> >
> > * Reversed the updates from last week, and re-booted with the
> > previous kernel. No improvement.
> >
> > * Fiddled with various Java system properties, as in
> > http://download.oracle.com/javase/6/docs/technotes/guides/net/properties.html
> > Nothing seemed to help.
> >
> > * Installed a Java 1.5, built the test program with it, ran the test program
> > under that. It failed just like the distro version.
> >
> > Any ideas?
> >
> > =========================================================
> > To run the attached test
> > javac nettest.java
> > java nettest <hostname> <optional-port-number>
> >
> > | - - - - - - - - - - - - - - - - - - - - - - - - -
> > import java.net.Socket;
> >
> > public class
> > nettest
> > {
> > public static void
> > main( String [] a )
> > {
> > if( a.length > 0 )
> > {
> > String host = a[0];
> > int port = 80;
> > if( a.length > 1 )
> > {
> > port = Integer.parseInt( a[1] );
> > }
> > try
> > {
> > Socket si = new Socket( host, port );
> > System.out.println( "Success connecting to "
> > + host );
> > }
> > catch( Exception e )
> > {
> > System.err.println( e.toString() );
> > e.printStackTrace();
> > }
> > }
> > else
> > {
> > System.err.println( "please provide host string" );
> > }
> > }
> > }
>
--
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| Steve White +49(331)7499-202
| E-Science Zi. 27 Villa Turbulenz
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| Astrophysikalisches Institut Potsdam (AIP)
| An der Sternwarte 16, D-14482 Potsdam
|
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