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Cybersecurity · head to head

Cisco Duo vs Tenable Nessus

Cisco Duo logo

Cisco Duo

Cybersecurity

Trusted access for all users, all devices

From
Free
Rated
-
Full reviewWebsite
Tenable Nessus logo

Tenable Nessus

Cybersecurity

Network vulnerability scanner

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Cisco Duo free tier limited to 10 users maximum; Tenable Nessus nessus Professional is $4,790 for one year, sold as an annual licence rather than a per scan or usage based fee
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which Cisco Duo and Tenable Nessus actually diverge.

Attributes where Cisco Duo and Tenable Nessus differ
AttributeCisco DuoTenable Nessus
PlatformsWebWindows, Linux, Macos, Cloud
FoundedUnknown2002

Identical on both: starting price (Free), pricing model (subscription), free tier (Yes), user rating (Not yet rated), category (Cybersecurity).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Cisco Duo

Nothing recorded that Tenable Nessus does not also cover.

Only in Tenable Nessus

  • Network scanning
  • Vulnerability detection
  • Configuration assessment
  • Malware detection
  • Compliance checking
  • Cloud security assessment
  • Mobile scanning
  • API access

What people use each for

The jobs each tool is most often brought in to do.

Cisco Duo

  • Eliminating phishing with passwordless authnot Tenable Nessus
  • Implementing zero trust with device trustnot Tenable Nessus
  • Protecting sessions from hijacking and theftnot Tenable Nessus
  • Managing compliance for regulated industriesnot Tenable Nessus

Tenable Nessus

  • Vulnerability scanning of servers, network devices and web applicationsnot Cisco Duo
  • Configuration and compliance auditing against hardening benchmarksnot Cisco Duo
  • Point in time assessments by consultants and penetration testersnot Cisco Duo

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Cisco Duo

  • Free tier limited to 10 users maximum
  • Licenses must be purchased in 10-user increments (under 100 users) or 25-user increments (100+ users)
  • Pricing is per-user per-month with minimum purchase increments

Tenable Nessus

  • Nessus Professional is $4,790 for one year, sold as an annual licence rather than a per scan or usage based fee
  • Support beyond the base entitlement costs an extra $400 per year for Advanced Support with 24x365 phone and chat access
  • The on demand training course is a separate $275 purchase for a single person for one year
  • Multi year discounts require paying for two or three years up front

Pricing, plan by plan

Cisco Duo

Free
  • FreeFree
    • Multi-factor authentication (MFA)
    • Seamless integrations
    • Authenticator app
  • Essentials$3/month
    • All Free features
    • Duo Directory
    • Phishing-resistant MFA
  • Advantage$6/month
    • All Essentials features
    • Identity intelligence
    • Cisco Identity Intelligence (ISPM, ITDR)
  • Premier$9/month
    • All Advantage features
    • Complete device trust
    • VPN-less remote access

Tenable Nessus

Free
  • Nessus EssentialsFree
    • Up to 16 ips
    • Network scanning
    • Vulnerability assessment
  • Nessus Professional$2600/year
    • Unlimited targets
    • Enterprise features
    • Advanced analytics
  • Nessus Expert$5200/year
    • All Professional features
    • Cloud integration
    • Advanced reporting

Which should you pick?

Choose Cisco Duo if

  • You want to start without paying.
Cisco Duo review

Choose Tenable Nessus if

  • You need network scanning.
  • You want to start without paying.
  • You work on Windows, Linux, Macos, Cloud.
  • You also want vulnerability detection.
Tenable Nessus review

Questions people ask

Is Cisco Duo or Tenable Nessus better?
Neither clearly leads. Cisco Duo starts at Free and Tenable Nessus at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Cisco Duo or Tenable Nessus?
Cisco Duo starts at Free and Tenable Nessus at Free.
Does Cisco Duo or Tenable Nessus run on more platforms?
Cisco Duo runs on Web. Tenable Nessus runs on Windows, Linux, Macos, Cloud.
Can I use Cisco Duo for free?
Both have a free tier, so you can try either at no cost before committing.
What is Cisco Duo best used for?
Cisco Duo is most often used for eliminating phishing with passwordless auth, implementing zero trust with device trust, protecting sessions from hijacking and theft, managing compliance for regulated industries. Of those, eliminating phishing with passwordless auth and implementing zero trust with device trust are not what Tenable Nessus is typically brought in for.
What can Cisco Duo do that Tenable Nessus cannot?
Tenable Nessus covers Network scanning, Vulnerability detection, Configuration assessment, Malware detection.

Answered from the vendors’ own pages

Cisco Duo: How much does Cisco Duo cost?

Cisco Duo Free is $0/user/month (up to 10 users). Paid plans start at $3/user/month (Essentials), $6/user/month (Advantage), and $9/user/month (Premier). Billing is per-user per-month.

Source
Tenable Nessus: What are the three Nessus offerings?

Nessus Essentials is a free introductory offering for educators, students, and career starters, limited to 16 IPs for scanning. Nessus Professional is designed for consultants and SMBs, providing unlimited IT scans across any location. Nessus Expert is the premium offering extending Professional with web application scanning, infrastructure-as-code scanning, and external attack surface assessment up to 5 domains.

Source
Cisco Duo: Is Cisco Duo free to try?

Yes, Duo Free offers multi-factor authentication and seamless integrations at $0/user/month for up to 10 users.

Source
Tenable Nessus: What OS platforms does Nessus support?

Nessus runs on Debian/Kali Linux, Fedora, FreeBSD, Mac OS X, Red Hat/CentOS, SUSE Linux, Ubuntu, and various Windows versions including Server 2008, 2012, and Windows 7-10.

Source
Cisco Duo: What is the minimum purchase for Cisco Duo?

Organizations must buy licenses in 10-user increments for under 100 users, or 25-user increments for 100 or more users. Plans are modifiable at any time.

Source
Tenable Nessus: Can I use Nessus to scan third-party networks as a consultant?

Yes, Tenable permits you to use Nessus to scan third-party networks. Nessus Professional is ideal for consultants.

Source
Cisco Duo: What does the Advantage plan add over Essentials?

Advantage ($6/user/month) adds identity intelligence, Cisco Identity Intelligence (ISPM, ITDR), Duo Passport, session theft protection, Active Directory Defense, and risk-based authentication.

Source
Tenable Nessus: Can Nessus perform PCI external scanning?

Yes, you can use Nessus Professional to perform external network scans as required by the PCI DSS 11.2.2 requirement.

Source
Tenable Nessus: What additional features does Nessus Expert provide?

Web application scanning, which is dynamic application security testing (DAST) providing comprehensive visibility and insight into web application security issues; scanning code repositories for vulnerabilities; and assessing external attack surface with subdomain discovery.

Source
Tenable Nessus: What support options exist for Nessus Professional?

Standard Support includes software upgrades, patches, plugin access, and 24x7 support via chat and community portal. Advanced Support adds 24x7 phone access and committed SLAs: P1 less than 2 hours, P2 less than 4 hours, P3 less than 12 hours, P4 less than 24 hours.

Source
Tenable Nessus: How frequently are Nessus plugins updated?

Nessus plugins are updated daily, based on when vendors and security research sites publish new vulnerabilities.

Source
Tenable Nessus: How does licensing work in virtual machine environments?

Whether you are using Nessus in a physical or a virtual environment, the IP addresses or hosts that you are scanning from must be licensed.

Source
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