meta-externalagent
Meta external agent web crawler bot
About this crawler
meta-externalagent is a web crawler identified by the regular-expression pattern meta-externalagent\/ in the User-Agent request header. It is categorised as ai-crawler, social-preview. Use the regex above to detect, log, allow, or block meta-externalagent traffic in your web server, CDN edge rules, or robots.txt.
Block-rate · top 25k sites
4.4%
Technical details
- Name
- meta-externalagent
- Pattern
meta-externalagent\/- Tags
- ai-crawler, social-preview
- Reference
- https://developers.facebook.com/docs/sharing/webmasters/web-crawlers
- Added
- 2024/10/03
- rDNS suffixes
.facebook.com,.fbcdn.net,.fbsv.net,.tfbnw.net- Instances
- 2 known sample(s)
rDNS verification (FCrDNS)
Verify a request is genuinely meta-externalagent 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.
.facebook.com.fbcdn.net.fbsv.net.tfbnw.net
Sample User-Agent strings
meta-externalagent/1.1 (+https://developers.facebook.com/docs/sharing/webmasters/crawler)
meta-externalagent/1.1
Block this crawler
robots.txt — disallow meta-externalagent:
User-agent: meta-externalagent
Disallow: /
Apache .htaccess — return 403:
RewriteEngine On
RewriteCond %{HTTP_USER_AGENT} meta-externalagent\/ [NC]
RewriteRule .* - [F,L]
Nginx — return 403 inside a server block:
if ($http_user_agent ~* "meta-externalagent\\/") {
return 403;
}
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