Install a Nessus Agent on Linux

Caution: If you install a Nessus Agent on a system where an existing Nessus Agent, Nessus Manager, or Nessus scanner is running nessusd, the installation process kills all other nessusd processes. You may lose scan data as a result.

Before You Begin

Download the Nessus Agent

On the Nessus Agents Download Page, download the package specific to your operating system.

Example Nessus Agent Package Names

Install Nessus Agent

Note: The following procedure requires root privileges.

Using the command line interface, install the Nessus Agent.

Example Linux Install Commands

You can install a full plugins set before linking to reduce the bandwidth impact during a mass installation. You can accomplish this by using the nessuscli agent update command with the --file parameter, which specifies the location the plugins set. You must do this before starting the Nessus Agent. For example:

/opt/nessus_agent/sbin/nessuscli agent update --file=./plugins_set.tgz

The plugins set must be less than five days old. A stale plugin set older than five days forces a full plugin download to occur. You can download a recent plugins set from the Nessus Agents download page.

Note: After installing a Nessus Agent, you must manually start the service using the command /sbin/service nessusagent start.

Link Agent to Nessus Manager

At the command prompt, use the nessuscli agent link command. For example:

/opt/nessus_agent/sbin/nessuscli agent link


--name=MyOSXAgent --groups="All" --port=8834

The supported arguments for this command are:

Argument Required? Value


Use the values you retrieved from the manager.
--host yes
--port yes


no Specify a name for your agent. If you do not specify a name for your agent, the name defaults to the name of the computer where you are installing the agent.
--groups no

Specify existing agent group or groups where you want to add the agent. If you do not specify an agent group during the install process, you can add your linked agent to an agent group later in Nessus Manager or

Note: The agent group name is case-sensitive and must match exactly.

--offline-install no

For Nessus Agents 7.0.3 or later, you can install the Nessus Agent on a system even if it is offline. Add the command line option offline-install="yes" to the command line input. The Nessus Agent periodically attempts to link itself to either or Nessus Manager.

If the agent cannot connect to the controller then it retries every hour, and if the agent can connect to the controller but the link fails then it retries every 24 hours.

--cloud no

Specify the --cloud argument to link to

The --cloud argument is a shortcut to specifying --port=443 (or --port=443 for agents 8.0.x and earlier).

Note: Starting with Nessus Agent 8.1.0, agents communicate with using If agents are unable to connect to, they use instead. Agents with earlier versions continue to use the domain.
--network no For agents, add the agent to a custom network. If you do not specify a network, the agent belongs to the default network.

If the information that you provide is incorrect, a "Failed to link agent" error appears.

Note: If you attempt to clone an agent and link it to Nessus Manager or, a 409 error may appear. This error appears because another machine was linked with the same UUID value in the /etc/machine_id or /etc/tenable_tag file. To resolve this issue, replace the value in the /etc/tenable_tag file with a valid UUIDv4 value. If the /etc/machine_id file does not exist, you can delete /etc/tenable_tag to generate a new value.

Verify a Linked Agent

To verify a linked agent in Nessus Manager:

  1. In the top navigation bar, click Scans.

    The My Scans page appears.

  2. In the left navigation bar, click Agents.

    The Agents page appears.

  3. Locate the new agent in the linked agents table.