Nessus – vulnerability scanner in Linux.
Go to the official website http://www.tenable.com/products/nessus/select-your-operating-system and download Nessus for the operating system that you have installed.
Switch to the root user:
su
Run the installation of the downloaded file, for example:
dpkg -i Nessus-7.0.2-debian6_amd64.deb
Run Nessus:
/etc/init.d/nessusd start
After that, you can open Nessus in the browser by clicking https://IP:8834/
For further work, you need to register with https://www.tenable.com/products/nessus/activation-code.