Nessus

Nessus began in 1998 as "The Nessus Project," a free remote security scanner created by Renaud Deraison and released under the GNU General Public License (GPL). It was designed to remotely probe networked systems for known vulnerabilities, misconfigurations, and missing patches, and it grew rapidly in popularity within the security community during the late 1990s and early 2000s as an accessible, extensible alternative to commercial scanners of the era.

Founding of Tenable

On September 16, 2002, Renaud Deraison co-founded Tenable Network Security, Inc. alongside Ron Gula and Jack Huffard. Deraison folded the Nessus project into the newly formed company, which took over its development and distribution going forward.

The Shift to Proprietary Licensing

A pivotal turning point came with the release of Nessus 3 on October 5, 2005: Tenable moved the scanner away from the GPL to a proprietary, closed-source license. Nessus 2.2.11 was the last version to remain under GPL terms. This change was controversial among parts of the open-source security community and directly led to the creation of OpenVAS, a fork of the older GPL-licensed Nessus 2 engine that continued development as free and open-source software (later carried forward under the Greenbone Sustainable Resilience project).

Growth as a Commercial Product

Under Tenable, Nessus evolved into a widely used commercial vulnerability assessment tool, supporting Linux, macOS, and Windows, with a large library of vulnerability-detection plugins mapped to CVE identifiers and used for both point-in-time scanning and compliance auditing. Tenable has continued to release regular version updates (for example, Nessus 8.15.8 on January 18, 2023) and, as of the mid-2020s, advertises coverage of well over 100,000 CVEs and hundreds of thousands of plugins, updated continuously by its research team.

Tenable's Corporate Trajectory

Tenable itself grew substantially as a company built around Nessus and later products: it raised a $50 million Series A round from Accel Partners in September 2012, a $250 million Series B round from Insight Partners in 2015 (reported at the time as the largest capital raise by a private cybersecurity company), and completed its initial public offering on Nasdaq (ticker: TENB) in July 2018. Leadership changed over time as well—Ron Gula moved to chairman in 2016 with Amit Yoran becoming CEO in January 2017, and in January 2025 Stephen Vintz and Mark Thurmond were named interim co-CEOs with Art Coviello as chairman.

Legacy

Nessus is frequently cited as one of the foundational tools of modern vulnerability management, and its open-source-to-proprietary transition is a commonly referenced case study in discussions of commercialization within the security tooling ecosystem. Some biographical details repeated across secondary sources—such as Deraison's exact age (reportedly 17) at the time of Nessus's initial 1998 release—are widely cited but are noted here as less rigorously sourced than the company's own corporate milestones.

Timeline

• 1998Renaud Deraison launches "The Nessus Project," a free, open-source (GPL) remote network vulnerability scanner.
• 2002-09-16Tenable Network Security, Inc. is founded by Ron Gula, Jack Huffard, and Renaud Deraison; Nessus is folded into the new company.
• 2005-10-05Nessus 3 is released, marking the transition from GPL open-source licensing to a proprietary license; Nessus 2.2.11 remains the last GPL version, later forming the basis of the OpenVAS fork.
• 2012-09Tenable raises a $50 million Series A funding round led by Accel Partners.
• 2015Tenable raises a $250 million Series B round from Insight Partners, reported as the largest private-cybersecurity-company capital raise at the time.
• 2016Ron Gula transitions to chairman of Tenable.
• 2017-01Amit Yoran becomes CEO of Tenable.
• 2018-07Tenable completes its initial public offering on Nasdaq under the ticker TENB.
• 2023-01-18Nessus 8.15.8 is released (documented stable release).
• 2025-01Stephen Vintz and Mark Thurmond are appointed interim co-CEOs of Tenable, with Art Coviello named chairman.