Installing Java Plugins for Firefox 3.6 on CentOS 5


I needed to get Java working with Firefox on my CentOS box.  The primary reason was to do some additional NAC testing with Linux.  I’ve been having a much harder time getting it installed than I originally thought.  I finally got it working and wanted to share my steps and links.

1.  Download the Java RPM from  I used the self extracting file.

2.  Create the /usr/java directory and place self extracting  file there

3.  Change the file to make it executable with “chmod a+x jre-6u21-linux-i586.bin”

4.  Execute the file by typing “./jre-6u21-linux-i586.bin”

5.  cd to the “/usr/lib/mozilla/plugins” directory

6.  Create the following two symbolic links within that directory

ln -s /usr/java/jre1.6.0_21/plugin/i386/ns7/

ln -s /usr/java/jre1.6.0_21/lib/i386/

7.  Close any open Firefox web browsers

8.  Open a Firefox web browser

9.  In the URL field, type “about:plugins”.  You should see references to Java plugins.

There are a lot of references on the internet that have the first symbolic link shown above, but the only reference I found to the second symbolic link was the second reference below.  That was the final step that made it work for me.


One response to “Installing Java Plugins for Firefox 3.6 on CentOS 5

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Nick Kelly

Cybersecurity Engineer, Cisco

Nick has over 20 years of experience in Security Operations and Security Sales. He is an avid student of cybersecurity and regularly engages with the Infosec community at events like BSides, RVASec, Derbycon and more. The son of an FBI forensics director, Nick holds a B.S. in Criminal Justice and is one of Cisco’s Fire Jumper Elite members. When he’s not working, he writes cyberpunk and punches aliens on his Playstation.


Virgilio “BONG” dela Cruz Jr.

CCDP, CCNA V, CCNP, Cisco IPS Express Security for AM/EE
Field Solutions Architect, Tech Data

Virgilio “Bong” has sixteen years of professional experience in IT industry from academe, technical and customer support, pre-sales, post sales, project management, training and enablement. He has worked in Cisco Technical Assistance Center (TAC) as a member of the WAN and LAN Switching team. Bong now works for Tech Data as the Field Solutions Architect with a focus on Cisco Security and holds a few Cisco certifications including Fire Jumper Elite.


John Cavanaugh

CCIE #1066, CCDE #20070002, CCAr
Chief Technology Officer, Practice Lead Security Services, NetCraftsmen

John is our CTO and the practice lead for a talented team of consultants focused on designing and delivering scalable and secure infrastructure solutions to customers across multiple industry verticals and technologies. Previously he has held several positions including Executive Director/Chief Architect for Global Network Services at JPMorgan Chase. In that capacity, he led a team managing network architecture and services.  Prior to his role at JPMorgan Chase, John was a Distinguished Engineer at Cisco working across a number of verticals including Higher Education, Finance, Retail, Government, and Health Care.

He is an expert in working with groups to identify business needs, and align technology strategies to enable business strategies, building in agility and scalability to allow for future changes. John is experienced in the architecture and design of highly available, secure, network infrastructure and data centers, and has worked on projects worldwide. He has worked in both the business and regulatory environments for the design and deployment of complex IT infrastructures.