meta-externalfetcher
Meta external fetcher web crawler bot
About this crawler
meta-externalfetcher is a web crawler identified by the regular-expression pattern meta-externalfetcher\/ in the User-Agent request header. It is categorised as social-preview. Use the regex above to detect, log, allow, or block meta-externalfetcher traffic in your web server, CDN edge rules, or robots.txt.
Block-rate · top 25k sites
1.2%
Technical details
- Name
- meta-externalfetcher
- Pattern
meta-externalfetcher\/- Tags
- 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-externalfetcher 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-externalfetcher/1.1 (+https://developers.facebook.com/docs/sharing/webmasters/crawler)
meta-externalfetcher/1.1
Block this crawler
robots.txt — disallow meta-externalfetcher:
User-agent: meta-externalfetcher
Disallow: /
Apache .htaccess — return 403:
RewriteEngine On
RewriteCond %{HTTP_USER_AGENT} meta-externalfetcher\/ [NC]
RewriteRule .* - [F,L]
Nginx — return 403 inside a server block:
if ($http_user_agent ~* "meta-externalfetcher\\/") {
return 403;
}
← back to all crawlers