Nessus
Nessus vulnerability scanner web crawler
About this crawler
Nessus is a web crawler identified by the regular-expression pattern Nessus in the User-Agent request header. It is categorised as scanner. Use the regex above to detect, log, allow, or block Nessus traffic in your web server, CDN edge rules, or robots.txt.
Block-rate · top 25k sites
0.33%
Technical details
- Name
- Nessus
- Pattern
Nessus- Tags
- scanner
- Reference
- https://www.tenable.com/products/nessus
- Added
- 2026/04/07
- rDNS suffixes
.tenable.com- Instances
- 1 known sample(s)
rDNS verification (FCrDNS)
Verify a request is genuinely Nessus with forward-confirmed reverse DNS: the client IP's PTR record must end in one of the suffixes below and a forward A/AAAA lookup of that hostname must return the same IP. UA strings alone are spoofable; FCrDNS is not.
.tenable.com
Sample User-Agent strings
Mozilla/5.0 (compatible; Nessus; http://www.nessus.org)
Block this crawler
robots.txt — disallow Nessus:
User-agent: Nessus
Disallow: /
Apache .htaccess — return 403:
RewriteEngine On
RewriteCond %{HTTP_USER_AGENT} Nessus [NC]
RewriteRule .* - [F,L]
Nginx — return 403 inside a server block:
if ($http_user_agent ~* "Nessus") {
return 403;
}
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