Nessus

Nessus is a vulnerability assessment solution from Tenable and one of the most widely used vulnerability scanners in the security industry. Originally created as an open-source project in 1998 and later developed as a commercial product, Nessus helps organisations identify and fix vulnerabilities, misconfigurations and compliance issues across their IT environments. Security teams and consultants face a constant stream of newly disclosed vulnerabilities, and without reliable scanning it is difficult to know which systems are exposed. Nessus addresses this with a fast, accurate scanning engine backed by an extensive and frequently updated library of plugins, providing detailed findings and remediation guidance. Its approach prioritises ease of use and low false-positive rates, making it suitable for both experienced professionals and those new to vulnerability assessment.

Nessus Professional supports unlimited assessments of IP addresses, with scanning for operating systems, network devices, databases, web servers, hypervisors and critical infrastructure. Pre-built policies and templates allow users to launch scans quickly, while configuration audits check systems against benchmarks such as CIS and DISA STIG. Live results update findings as new plugins are released without requiring a full rescan, and vulnerability priority ratings help focus remediation efforts. Reports can be customised and exported in multiple formats for technical teams and management. Nessus Expert extends capabilities to external attack surface discovery, web application scanning and infrastructure-as-code assessment for cloud environments. Nessus Essentials is a free version for students, educators and those starting out, limited to a small number of IP addresses. Nessus can be installed on Windows, macOS and Linux, as well as deployed as a virtual appliance, and it integrates into Tenable's broader exposure management platform, including Tenable Vulnerability Management and Tenable Security Center. Typical users include penetration testers, security consultants, IT administrators and security teams in organisations of all sizes. A free version and free trial are available, with Nessus Professional priced from around USD 4,000.20, typically per year.