Step 1: Download the agent installer
Head to the Nessus agent download page:
Search for the .dmg installer file (i.e. NessusAgent-X.X.X.dmg)
Download the file and keep a note where you've saved it.
Step 2: Install the agent
Double-click on the .dmg file and then double-click the "Install Nessus Agent.pkg" installer.
Follow the steps to complete the installation process.
Step 3: Configure and link the agent
To configure each device for scanning you'll need two pieces of information, your Prefix and a Key. You can find these in the Internal Scanning section of the settings page inside the Intruder portal:
Calculate your DeviceName as follows:
DeviceName = Prefix_TargetName
... where TargetName is what you'd like the target to be called in the portal.
For example, if your Prefix is DQEGBQUAAAc and your want to name your device 'paul-laptop':
DeviceName = DQEGBQUAAAc_paul-laptop
Once you have the above information ready, open the Terminal app and run the following command - modifying the placeholders (everything inside [ ] brackets) accordingly:
sudo /Library/NessusAgent/run/sbin/nessuscli agent link --name=DeviceName --cloud --key=Key