The Nessus server utilizes plugins to determine which flaws exist on the target hosts. The Nessus server (a Windows service or a Linux daemon called nessusd) performs the actual scanning while the client presents the user with an interface and passes commands to the server.

On both operating systems, Nessus operates as a server and as a client. Nessus is available for both Linux and Windows. In this way Nessus is very similar to BeyondTrust Retina however, these two tools have very different user interfaces and Nessus is undoubtedly more popular and widely used, as multiple surveys on have shown over the years. Some of these flaws include outdated and vulnerable software, improper configurations such as accounts with default passwords or without password protection, and the presence of risky services or daemons. During its scans, Nessus probes ports and checks for potential software flaws that could be exploited by hackers or malware. Nessus is designed to comprehensively scan network hosts for vulnerabilities and generate reports based on its findings. If Nmap is the most popular free network scanning tool, then Nessus by Tenable is undoubtedly the most widely used commercial security application.

How to use nessus safely