Nessus Activation Code Installation

The following will provide directions to re-register an existing Nessus scanner as well as directions to register a new Nessus scanner.

Register a Nessus Activation Code to an Existing Nessus Scanner

To apply a registration code to an existing Nessus scanner, log in with an administrator account. In the upper left corner, select the drop-down under the username and select “Settings”:

Click on the pencil next to the current Activation Code to update your code:

This will bring up a dialog box for inputting your new activation code. Click “Save” when complete:

Nessus will now download the latest plugins:

Nessus will restart and you will need to log in again:

Register a Nessus Activation Code for a New Nessus Scanner

To obtain the Activation Code for the Nessus Subscription, please log into your Tenable Support Portal, click “Activation Code” under the main menu and then click “+” next to the product name.

Scanner activation is performed through a web interface during the installation process.

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/nessuscli fetch –-challenge
FreeBSD # /usr/local/nessus/bin/nessuscli fetch –-challenge
Mac OS X # /Library/Nessus/run/bin/nessuscli fetch --challenge
Windows C:\Program Files\Tenable\Nessus>nessuscli.exe fetch --challenge

This will produce a string called “challenge” that looks similar to 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 plugins. 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

Once the nessus-fetch.rc file has been copied, run the nessuscli fetch command to install the file:

Platform Directory
Linux # /opt/nessus/bin/nessuscli fetch --register-offline
FreeBSD # /usr/local/nessus/bin/nessuscli fetch --register-offline
Mac OS X # /Library/Nessus/run/bin/nessuscli fetch --register-offline
Windows C:\Program Files\Tenable\Nessus>nessuscli.exe fetch --register-offline
"C:\Program Files\Tenable\Nessus\conf\nessus-fetch.rc"

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

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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