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Nessus is one of the most popular and capable vulnerability scanners, particularly for UNIX systems. It was initially free and open source, but they closed the source code in 2005 and removed the free "Registered Feed" version in 2008. It now costs $2,190 per year, which still beats many of its competitors. A free “Nessus Home” version is also available, though it is limited and only licensed for home network use.
Nessus is constantly updated, with more than 70,000 plugins. Key features include remote and local (authenticated) security checks, a client/server architecture with a web-based interface, and an embedded scripting language for writing your own plugins or understanding the existing ones.
Read 25 reviews.
Latest release: version 6.3.3 on March 16, 2015 (5 years, 8 months ago).
OpenVAS is a vulnerability scanner that was forked from the last free version of Nessus after that tool went proprietary in 2005. OpenVAS plugins are still written in the Nessus NASL language. The project seemed dead for a while, but development has restarted.
Read 40 reviews.
Latest release: version 8.0 on April 2, 2015 (5 years, 8 months ago).
SAINT is a commercial vulnerability assessment and penetration system. It was originally developed in the late 1990's as free UNIX tool based on the open source SATAN scanner. Later it went commercial and broadened into a whole suite of tools for vulnerability detection, exploitation, and asset management. It is available on multiple platforms, including appliances (SAINTbox) and cloud-hosted (SAINTcloud). Top competitors include Nessus, Nexpose, and QualysGuard.
Read 9 reviews.
Latest release: version 9.8 on May 1, 2020 (7 months, 1 week ago).