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Tenable Nessus

If Nmap is the most popular free network scanning tool, then Nessus by Tenable is undoubtedly the most widely used commercial security application. Nessus is designed to comprehensively scan network hosts for vulnerabilities and generate reports based on its findings. During its scans, Nessus probes ports and checks for potential software flaws that could be exploited by hackers or malware. Some of these flaws include outdated and vulnerable software, improper configurations such as accounts with default passwords or without password protection, and the presence of risky services or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. 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.

Nessus is available for both Linux and Windows. On both operating systems, Nessus operates as a server and as a client. 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. The Nessus server utilizes plugins to determine which flaws exist on the target hosts. Plugins are small programs that look for specific vulnerabilities (Nessus contains tens of thousands of them). When Nessus can connect to the Internet it automatically downloads the latest plugins which will enable it to recognize and report on the latest known software weaknesses (such as those disclosed by Mitre). There is even an embedded scripting language (known as NASL) for writing your own custom plugins.

Nessus login interface

Nessus v5.x login interface

Nessus login interface

Nessus v4.4.x login interface

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Written by Doug Vitale

March 2, 2012 at 2:08 PM

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