Switch to a machine with to download the required license. Install Tenable Nessus Offline

Alternative Command-Line Method: If the Web UI is inaccessible, extract the challenge code via the command-line interface (CLI) using root or administrative privileges:

This requires a manual "handshake":

> "C:\Program Files\Tenable\Nessus\nessuscli.exe" fetch --challenge

We will walk through the process using a as the target, but the steps are conceptually identical for Windows or macOS. Replace file paths and executables accordingly.