masscan
Masscan network scanner web crawler bot
About this crawler
masscan is a web crawler identified by the regular-expression pattern masscan in the User-Agent request header. It is categorised as scanner. Use the regex above to detect, log, allow, or block masscan traffic in your web server, CDN edge rules, or robots.txt.
Block-rate · top 25k sites
0.065%
Technical details
- Name
- masscan
- Pattern
masscan- Tags
- scanner
- Reference
- https://github.com/robertdavidgraham/masscan
- Added
- 2026/04/07
- Instances
- 1 known sample(s)
Sample User-Agent strings
masscan/1.0 (https://github.com/robertdavidgraham/masscan)
Block this crawler
robots.txt — disallow masscan:
User-agent: masscan
Disallow: /
Apache .htaccess — return 403:
RewriteEngine On
RewriteCond %{HTTP_USER_AGENT} masscan [NC]
RewriteRule .* - [F,L]
Nginx — return 403 inside a server block:
if ($http_user_agent ~* "masscan") {
return 403;
}
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