Running WebEx on Linux

These instructions were written with reference to the Firefox browser, and Redhat Eterprise Linux 5 / CentOS 5. They are primarily for users of Bruker and Agilent NMR spectrometers who wish to allow someone from either of these companies to run their spectrometer remotely for testing purposes.

(Insert usual disclaimer - I’m not an expert and have not tried to investigate every possible way of getting WebEx going - this is just what works for me).

To use WebEx your browser must be able to run Java applications. Once Java has been set up, I have never experienced any other problems. Just wait for your friendly Bruker or Agilent representative to email you an invitation to a meeting, click on the link (or paste it into your browser if your browser doesn’t open it automatically) and accept the invitation to the meeting. As far as I am aware, no modifications to your firewall are necessary.

 

Is your browser already Java enabled?

To see if Java is enabled, point your browser here or here.
You might have to wait a minute to see the result.

If Java is not enabled you’ll probably need to

  1. download and install it. I’d suggest installing the Java runtime environment (JRE), not the Java development kit (JDK). The JDK includes the runtime environment, so I think that will do the job (haven’t tried it myself), but it also includes stuff for developing Java applications, which you don’t need.
  2. Create a symbolic link from your browser’s plugin directory to the file libnpjp2.so
  3. You’ll probably then need to restart the browser. This is usually enough, but if it still says Java is not enabled, follow the instructions in the Enabling the Plugin section of these notes.
These notes assume you have root access. If you don’t, you might still be able to get it running by downloading the tar.gz JRE archive, extracting it into a subdirectory of your home directory, and following the instructions below to create the symbolic link. If the Firefox plugins directory won’t let you create the symbolic link, you’ll have to download the tar.bz2 Firefox archive and install that under your home directory as well. Then you will need to create the symbolic link in this new Firefox, and test it to see if Java works on it.
Note: I have not tried this myself.


Checking to see if the Java Runtime Environment is installed on your computer.

There are two ways that the Java Runtime Environment (JRE) could have been installed on your computer (or which you can later use to install it).
  1. It could have been installed as a package that is part of the Red Hat / CentOS distribution.
    Red Hat / CentOS use the Redhat Package Manager (rpm) and Yellowdog Updater Modified (yum) to install and remove software. To check this, type the first line below.
    yum list installed |grep jre
    jre.i586                                1.7.0_09-fcs                   installed
    
    For the 64 bit version the response will be similar to...
    jre.x86_64                              1.6.0_29-fcs                   installed
    
    (Ignore any lines containing “jrefactory” - this is not the JRE).
    It might not have been installed using rpm, in which case it will not appear using the yum command.

  2. It could have been downloaded as an archive file (usually a file with a tar.gz extension) and untarred into any directory. This might make it difficult to check whether it has been installed because it could be anywhere on your system. However if the “locate” database is running (which it is by default) you can search for a file which is part of the distribution by typing
    locate libnpjp2.so
    
    This will probably also show files belonging to the JRE installation which is part of Topspin or VnmrJ. I have not had success linking to these files, but there’s no harm in trying them. Note that if they work at all, they will only work for 32 bit browsers.

    If "locate" doesn’t work on your system, have a look in /usr/local to see if there are any directories with names starting “jre”. If it hasn’t shown up at this stage, you can assume it’s not installed, and proceed with your own installation. Even if there is an old JRE sitting in an obscure directory, it should not affect us.
    However if you’re really keen to find an existing JRE installation, and don’t feel like getting “locate” working, type (as root)

    find / -name libnpjp2.so -print
    
    and go and have lunch while it searches through all the disks on your system
If the Java Runtime Environment is not installed on your system, check whether you need a 32 or 64 bit version as described below, then go to the Downloading the Java Runtime Environment section of these notes.
 

32 or 64 bit?

Your version of Linux could be either 32 bit or 64 bit. To check, open a terminal and use the uname command...
uname -a
Linux wolfgang 2.6.18-308.16.1.el5 #1 SMP Tue Oct 2 22:01:37 EDT 2012 i686 i686 i386 GNU/Linux
Linux russell 2.6.18-308.20.1.el5 #1 SMP Tue Nov 13 10:15:12 EST 2012 x86_64 x86_64 x86_64 GNU/Linux
The first response line above is from a 32 bit machine called wolfgang, and the second line is from a 64 but machine called russell.

A 32 bit machine can only run 32 bit software, so the version of Firefox must also be 32 it. A 64 bit machine can run either 32 bit or 64 bit software (assuming it has the necessary libraries installed), so you need to do a further test to see what version of Firefox is installed. Type about: in the address bar. At the bottom of the page that appears, you will see something like

Build identifier: Mozilla/5.0 (X11; Linux i686; rv:10.0.10) Gecko/20121026 Firefox/10.0.10
for a 32 bit version of Firefox, or

Build identifier: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.10) Gecko/20121025 Firefox/10.0.10
for a 64 bit version. (It’s the i686 or x86_64 part that interests us here).

 

The Plugins Directory

This should be
/usr/lib/mozilla/plugins   for 32 bit firefox, or
/usr/lib64/mozilla/plugins   for 64 bit firefox

Have a look here to check whether the link to the Java Runtime Environment exists.

cd  /usr/lib64/mozilla/plugins
ls -l
If it does, you’ll see something like
libnpjp2.so -> /usr/java/latest/lib/amd64/libnpjp2.so
or slightly different for 32 bit versions. If you see this, do
ls -l /usr/java/latest/lib/amd64/libnpjp2.so
to check that the symbolic link is really pointing at something that exists on disk, and has not been removed at some time.

 

Enabling the Plugin

If the plugin is there but the links at the top of this page say that Java is not enabled, look in the Tools menu in Firefox, and select Add-ons. If you see a Java(TM) Plug-in line with an Enable button, click on this button to enable Java.

 

Downloading the Java Runtime Environment

If the JRE is not installed on your system, point your browser at the Java Download site. Here you have a choice of 32 or 64 bit, and of rpm or tar.gz formats.

If you select the rpm format, you should see a popup window offering you the option to either save the file, or open it with the software installer. You can save the file and install it later if you like, but it might be simpler to run the software installer straight away. If you do this, you will get another popup asking for the root password. Once you have supplied this, you need to click on Apply in the next popup window, and installation will proceed. It won’t get very far before it warns you that it is unable to verify the software. This is because it didn’t come from the Red Hat or CentOS repositories. Click on "Install anyway".

 

You should soon see a "Software installed successfully" popup, possibly with some warnings.
The final graphic above shows the window to save the tar.gz version. Remember you need the rpm or the tar.gz version, not both.


 
If you elect to save the rpm version instead of running the software installer, you will get a file like jre-6u37-linux-i586-rpm.bin
(Of course the name will be slightly different for a 64 bit version).
Notice the .bin extension. You will need to extract the rpm file by making this executable and running it...
chmod 755 jre-6u37-linux-i586-rpm.bin
 ./jre-6u37-linux-i586-rpm.bin
Unpacking...
Checksumming...
Extracting...
UnZipSFX 5.50 of 17 February 2002, by Info-ZIP (Zip-Bugs@lists.wku.edu).
  inflating: jre-6u37-linux-i586.rpm
error: can’t create transaction lock on /var/lib/rpm/__db.000

Done.
The error above did not seem to affect anything.
You now have the file jre-6u37-linux-i586.rpm
It can be installed as follows:
# rpm -ivh jre-6u37-linux-i586.rpm
Preparing...                ########################################### [100%]
   1:jre                    ########################################### [100%]
Unpacking JAR files...
        rt.jar...
        jsse.jar...
        charsets.jar...
        localedata.jar...
        plugin.jar...
        javaws.jar...
        deploy.jar...

 
If you prefer the tar.gz format, download the file (select the option to save it rather than open it with the Archive Manager), then change to the desired installation directory and untar it.
For example it you downloaded this file to the directory /home/chris/Downloads and you want to install the software in /usr/local, first become root, then
cd /usr/local
tar xvf /home/chris/Downloads/jre-7u9-linux-i586.tar.gz

 

Creating the Symbolic Link

When the JRE is installed, you should be able to change to the plugins directory...
cd /usr/lib/mozilla/plugins       (or /usr/lib64/mozilla/plugins)
and create a symbolic link to the plugin. If you installed the rpm version, the command will be similar to...
ln -s /usr/java/jre1.7.0_09/lib/i386/libnpjp2.so .

If you installed the tar.gz version, the symbolic link will be to a different directory. In the example above

cd /usr/lib/mozilla/plugins       (or /usr/lib64/mozilla/plugins)
ln -s /usr/local/jre1.7.0_09/lib/i386/libnpjp2.so .
(The i386 above will be amd64 for a 64 bit installation).

* Note that each of the ln -s commands above ends with a “space   dot”.

Finally, exit from your browser, open it again, return to this page, and click on one or both of the links at the top of this page to see if Java is now enabled. If all went well, it should now work. If not, check that the plugin is enabled as described in the Enabling the Plugin section of this page.

 

If the browser is not happy...

If your browser is not happy with the plugin, it could spontaneously close each time you try to test Java. If this happens, you could just remove the symbolic link and give up - there should be no adverse effects to your system. However a better option would be to either install a newer version of Firefox, or remove the version of JRE that you have just installed, and install an older version.
If you installed the rpm version, check the file with
yum list installed |grep jre
Then do
 yum remove jre.i586
replacing jre.i586 with whatever version of the package that yum found.
Loaded plugins: fastestmirror
Setting up Remove Process
Resolving Dependencies
--> Running transaction check
---> Package jre.i586 0:1.7.0_09-fcs set to be erased
--> Finished Dependency Resolution

Dependencies Resolved

================================================================================
 Package       Arch           Version                 Repository           Size
================================================================================
Removing:
 jre           i586           1.7.0_09-fcs            installed            91 M

Transaction Summary
================================================================================
Remove        1 Package(s)
Reinstall     0 Package(s)
Downgrade     0 Package(s)

Is this ok [y/N]: y
Downloading Packages:
Running rpm_check_debug
Running Transaction Test
Finished Transaction Test
Transaction Test Succeeded
Running Transaction
  Erasing        : jre                                                      1/1

Removed:
  jre.i586 0:1.7.0_09-fcs

Complete!
If you installed the tar.gz version, you could leave it where it was installed, and just remove the symbolic link from the Firefox plugins directory. If you would prefer to remove it, change to the directory where you installed it...
cd /usr/local
rm -r jre1.7.0_09

 

Installing an older version of Java

An older version of Firefox kept spontaneously closing when I tried to use it with Java version 1.7. It was quite happy with version 1.6 which you can download here.

The method for installing it is the same as described above.


An Easier Way?

I’ve been told that if you install the java-1.6.0-sun-plugin package, that Java “should just work”. Only problem is finding this package. It is located in the “workstation” (RHEL5) or “supplementary” (RHEL6) sub-channel which is not activated by default when you subscribe to Red Hat Network. You can check which channels your system is subscribed to by typing
yum repolist all


Other Linux Distributions

Red Hat, CentOS, and many other Linux distributions use the Redhat Package Manager (rpm) as described above. Other distributions such as Debian, Ubuntu and Mint use the Advanced Package Tool (apt). On these distributions, the instructions on this page for installing tar.gz JRE archives will still work, but you probably will not be able to install an rpm distribution.
On my Ubuntu 11.04 system I’ve installed icedtea which is an alternative to the standard Java Runtime Environment.
To see what is available, type
apt-cache search iced
and / or
apt-cache search jre
Choose an openjdk or an icedtea package and install it with (for example)
apt-get install icedtea-6-plugin
If it has any dependencies, it will install other necessary packages as well.

Useful Links

Use the Java plugin to view interactive content on websites

Download and install 32-bit Java for Linux

JRE 7 Installation for Linux Platforms

If you find any mistakes in this document, or have any suggestions, email me at Chris dot Blake at anu.edu.au and let me know.


Last updated: 20 November 2012

Australian National University NMR Centre