Nessus (Tenable)
Popular vulnerability scanner; free Essentials for up to 16 IPs.
Freemium Desktop download
- Platforms
- Windows/Linux/macOS (local web UI on port 8834)
- Licence
- Freemium — Essentials free (16 IPs)
- Price
- Essentials free; Professional from ~$4,390/yr
- Updated
- 2026-11-05
What it is
Nessus is a widely used vulnerability scanner. It checks servers, network gear and applications for known vulnerabilities and misconfigurations, surfacing unpatched systems and weak passwords. The free Essentials edition covers 16 addresses.
Problems it removes
- You need to know which systems carry known vulnerabilities and misconfigurations.
- Servers and network gear need regular authenticated vulnerability scans.
- A small environment needs a free, credible scanning option.
How administrators use it
- Install Nessus and scan hosts, using authenticated scans for depth.
- Triage findings by severity and track remediation.
- Use the free Essentials edition for up to 16 IPs; Professional for more.
Strengths & trade-offs
Strengths
- Extensive, well-maintained vulnerability checks.
- Free Essentials tier.
- Clear, actionable reports.
Trade-offs
- Professional is a yearly subscription.
- Essentials is capped at 16 IP addresses.
Common questions
Is there a free version?
Yes — Nessus Essentials, for up to 16 IP addresses.
Does Nessus fix vulnerabilities?
No — it finds and prioritises them; remediation is up to you.