Activation Code Installation

Thank you for registering your Nessus® subscription!

You must retrieve your Activation Code for the Nessus subscription from either your Tenable Support Portal account for Nessus or your Nessus Home registration email. You must purchase a subscription to use Nessus in a professional environment even if it is not directly for commercial purposes. This includes scanning your desktop at work or a home computer that is used for business purposes. Please review the Subscription Agreement for more details on the type of subscription for which you are qualified.

Note that you can only use your Activation Code for one scanner, unless the scanners are managed by Tenable SecurityCenter™.

As of Nessus 5, scanner activation is performed through a web interface during the installation process.

Note that, by default, Nessus will attempt to update its plugins every 24 hours after you have registered it. If you do not want such an update attempted, edit the “auto_update” setting to “no” under Configuration -> Advanced within the Nessus GUI.

Nessus Without Internet Access

If your Nessus installation cannot reach the Internet directly, use the following procedure to register and update plugins:

On the system running Nessus, type the following command:

Platform Command to Run
Linux # /opt/nessus/bin/nessus-fetch –-challenge
FreeBSD # /usr/local/nessus/bin/nessus-fetch –-challenge
Mac OS X # /Library/Nessus/run/bin/nessus-fetch --challenge
Windows C:\Program Files\Tenable\Nessus>nessus-fetch --challenge

This will produce a string called "challenge" that looks similar to the following:


Next, go to and paste the "challenge" string as well as the Activation Code that you received previously into the appropriate text boxes. This will produce a URL that will give you direct access to the Nessus plugin feed. Save this URL because you will use it every time you update your plugins. In addition, it will produce a file called nessus-fetch.rc. Copy this file to the host running Nessus in the appropriate directory:

Platform Directory
Linux # /opt/nessus/etc/nessus/
FreeBSD # /usr/local/nessus/etc/nessus
Mac OS X # /Library/Nessus/run/etc/nessus
Windows C:\Program Files\Tenable\Nessus\conf

Next, run the following command to register Nessus offline, and install the nessus-fetch.rc file to the Nessus directory on the host:

Platform Command to Run
Linux # /opt/nessus/bin/nessus-fetch --register-offline /opt/nessus/etc/nessus/nessus-fetch.rc
FreeBSD # /usr/local/nessus/bin/nessus-fetch --register-offline /usr/local/nessus/etc/nessus/nessus-fetch.rc
Mac OS X # /Library/Nessus/run/bin/nessus-fetch --register-offline /Library/Nessus/run/etc/nessus/nessus-fetch.rc
Windows XP/2k3 C:\Program Files\Tenable\Nessus>nessus-fetch.exe --register-offline "C:\Documents and Settings\All Users\Application Data\Tenable\Nessus\conf\nessus-fetch.rc"
Windows Vista/7/8/2008/2012: C:\Program Files\Tenable\Nessus>nessus-fetch.exe --register-offline "C:\ ProgramData\Tenable\Nessus\conf\nessus-fetch.rc"

Note that, by default, Nessus will attempt to update its plugins every 24 hours after you have registered it. If you do not want this online update attempted, edit the “auto_update” setting to “no” under the “Configuration” -> “Advanced” menu.

You can obtain the newest plugins by going to the URL that was provided in the previous step. Here, you will receive a TAR file (e.g., all-2.0.tar.gz). Copy the file to the Nessus scanner system and then type the appropriate command for your platform:

Platform Command to Run
Linux # /opt/nessus/sbin/nessus-update-plugins all-2.0.tar.gz
FreeBSD # /usr/local/nessus/sbin/nessus-update-plugins all-2.0.tar.gz
Mac OS X # /Library/Nessus/run/sbin/nessus-update-plugins all-2.0.tar.gz
Windows C:\Program Files\Tenable\Nessus>nessus-update-plugins all-2.0.tar.gz

Resetting Activation Code

If for some reason you receive an error (such as “Code in Use”) regarding your Activation Code through the Nessus scanner (perhaps caused by a hardware crash, moving the scanner to a new host, software upgrade, or installation difficulties), you can reset your Nessus Activation Code from your Tenable Support Portal account. If you are using Nessus Home, you will have to register for and obtain a new activation code.

To reset your code from your Tenable Support Portal account, go to “Activation Codes”, click on “+” to display the Activation Code, and then click on “x” under the reset column for the code you want to reset. Once your code has been reset, you will need to re-register your scanner to receive plugins. Please view the Nessus 5.0 Installation and Configuration Guide for more information. Read more about Tenable Support Portal features.

Using Nessus with Tenable SecurityCenter

If you are using Tenable SecurityCenter, the Activation Code and plugin updates are managed from SecurityCenter. Nessus needs to be configured appropriately to communicate with SecurityCenter. When performing the installation of the Nessus scanner, when prompted for the Plugin Feed Registration noted above, enter ‘SecurityCenter’ as your Activation Code.

Please refer to the SecurityCenter documentation for the configuration of a centralized plugin feed for multiple Nessus scanners.

If you have any questions, feel free to request help using email support from the Tenable Support Portal, post a question to the Nessus Discussion Forums, or review the Nessus documentation.

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