1) Go to here and click the link to obtain an activation code. Click on the Professional Feed or Home Feed option. Request an evaluation license, fill out the requested information and wait for your activation code to arrive via email.
2) Next, go to the Nessus site and download Nessus – available here. Double click the installer. Click Next on the first screen.
3) On the License agreement screen, choose the “I accept the terms in the license agreement" radio button and click Next.
4) Choose a destination folder to install Nessus to and click Next.
5) Choose the Complete installation and click Next.
6) Click Install. After the program has finished installing, click Finish.
7) A new desktop icon should appear after the installation completes. Double click on Nessus Server Manager.
8) Nessus will ask you to enter your activation code (Figure 1). Enter the code you received in step 1 and click “Register". Nessus will start downloading and installing the plugins that enable Nessus to perform scans. This process may take a while (30+ minutes) depending on the speed of your computer.
9) The server manager will be left open when the plugin installation finishes. Click on the “Manage Users…" button.
10) Click the ~ez_ldquo+ez_rdquo~ button to add a new user. Enter a username and password, select the “Administrator" checkbox and click Save.
11) You can close the window – Nessus will run as a service.