Lots of people struggle with installing the agent – which is why we are working on improving the process, but until then, we hope you find this article helpful.

Outlined below are some scenarios and troubleshooting steps that we believe – if followed carefully – should remediate the installation issue(s) you're facing. Please bear in mind, it can take a few minutes for the internal system to show on your targets page.

If, by the end of this article, you're still having trouble, please get in touch with the team by sharing a screenshot of your most recent agent status output and the linking command you ran.

There are three attributes that you need to update in order for the target to link correctly and show up in your portal: the prefix, the device name and the key. If you omit any of these, it won't work.

MacOS
sudo /Library/NessusAgent/run/sbin/nessuscli agent link --name=[Prefix_DeviceName] --cloud --key=[KEY]

Windows
msiexec /i "NessusAgent-[version]-x64.msi" NESSUS_SERVER="cloud.tenable.com:443" NESSUS_KEY=[KEY] NESSUS_NAME=[Prefix_DeviceName] /qn

Linux
sudo /opt/nessus_agent/sbin/nessuscli agent link --name=[Prefix_DeviceName] --key=[KEY] --cloud

If your original linking command is missing any of these, you'll need to unlink and link again

It must be run in the directory where the agent was downloaded to.

Re-run the command in the correct directory.

You must have enough licenses to cover all of the internal targets added to the platform, even if you haven't scanned them yet. (Unscanned external targets don't have any bearing on the license count).

(For example: All licenses will be considered "in use" in the following scenario:
You have 100 licenses, 97 are consumed, three internal targets have been added and are awaiting a scan.)

If you're short, you'll see a notification similar to this in your portal:

If you're unsure about your current license count, then please head to Targets > Licenses:

If you're out of licenses, then you can update your license count by following the instructions in this article.

Please note that the trial entitles you to five licenses, which can be used to scan five targets (internal or external) as many times as you like for 14 days. Deleting the target will not release the license. If you have already used all five and would like to test the internal scanner, please get in touch with a member of the team via the chatbot.

If you did, I'm afraid the target won't show up.

To remedy this, we'd recommend following the steps in this article.

The agent needs to be able to reach out to cloud.tenable.com on port 443 to return the results to the platform. To test this, open your browser and type: https://cloud.tenable.com

Sounds simple – but sometimes turning your machine off and back on again, can do the trick.

If you launched the installer after downloading it (step 1), rather than via the install command (step 3), you will need to unlink your agent and relink again.

In the terminal, as Admin, run the following command
nessuscli agent unlink

Check that the unlink command worked
Run the agent status, it should return:

Linked to: None
Link status: Not linked to a manager

Link the agent (again)

If the answer is yes and you have an IT department, we'd recommend taking a screenshot of the process name in your task explorer (usually something like "nessusagent", "neagent" or similar) and sending it over to them; along with a note that says the agent needs to be able to reach out out to cloud.tenable.com on port 443.

Your best bet at this point would be to do the following: