Offline activation is required when your Nessus scanner is installed on a machine that cannot connect directly to Tenable's cloud licensing servers (e.g., classified networks, isolated internal labs, or firewalled environments). The process involves:
: On the offline machine, run the command to get your unique challenge code: /opt/nessus/sbin/nessuscli fetch --challenge
Locate the specific Nessus Professional activation code causing the error.
With the license now active, install the plugin package: nessus offline activation license already in use full
Log into your offline Nessus scanner host via the command line (Terminal for Linux/macOS or Command Prompt as Administrator for Windows).
Even though your scanner is offline, you must use an online machine to check your Tenable license usage.
Step-by-Step Resolution: Resetting Your Nessus Activation Code Offline activation is required when your Nessus scanner
Copy the long, alphanumeric string displayed in the output. Keep this terminal window open. Step 3: Download the Offline License and Plugins
The "license already in use" error triggers when Tenable's backend registration portal flags the activation code as already mapped to a different challenge key. Common triggers include:
: /opt/nessus/sbin/nessuscli fetch --register-offline nessus.license Even though your scanner is offline, you must
This error occurs when the Nessus license server believes the activation code is already active on another machine, or if a previous installation wasn’t properly deactivated before a reinstall.
To fix this issue, you must manually break the bond between your activation code and the old challenge string. You can do this directly through your Tenable management console.