Nessus uses "plugins" to detect vulnerabilities. In a standard setup, Nessus pulls these updates automatically from Tenable’s servers. However, for scanners located in or behind restrictive firewalls, you must download the all-2.0.tar.gz archive manually from a machine with internet access and transfer it to the scanner. How to Download the Newest Version

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

Ensure the file did not get corrupted during transfer. Check the MD5 checksum provided on the Tenable download page against your local file.

On your offline Nessus scanner, run the following command in the terminal/command prompt: Linux: /opt/nessus/sbin/nessuscli fetch --challenge

After the command completes, Nessus will begin "Processing Plugins." This can take anywhere from 10 to 30 minutes depending on your hardware. while this is happening.

Ensure you have at least 5GB of free space. The extraction process requires significant temporary storage.