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How to Block User Agents and Referrer Sites

Created by: Jesper Verkade

Modified on: Wed, 27 May, 2020 at 3:49 PM

Blocking IP addresses, User Agents or Referres may cause unforseen issues, since it's easy to block more then expected.


How to Block User Agents

First you need to know what User Agent you wish to block. You can retrieve such information from the access logs (/var/log/nginx/access.log)

{"time":"2020-01-27T13:08:05+00:00", "remote_addr":"", "remote_user":"", "host":"", "request":"GET / HTTP/1.1", "status":"200", "body_bytes_sent":"87", "referer":"", "user_agent":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.130 Safari/537.36", "request_time":"0.000", "handler":"", "country":"NL", "port":"80", "ssl_cipher":"", "ssl_protocol":""}

Once you know which User Agent you wish to blacklist you can follow the instructions below:

  • Create or update the server.blacklist file in /data/web/nginx/with:
    sensible-editor /data/web/nginx/server.blacklist
  • Add the following snippet and include the User Agent you wish to block in the first line after $http_user_agent ~ ":
    if ($http_user_agent ~ "Windows 95|Windows 98||xpymep|TurnitinBot|sindice|Purebot|libwww-perl") {
        return 403;

How to Block Referrer Sites

Blocking a referrer site is not much different from blocking a User Agent. Simply create or update the server.blacklist file again in /data/web/nginx/with:

sensible-editor /data/web/nginx/server.blacklist

and paste the following snippet:

if ($http_referer ~* (seo|referrer|redirect|babes|click|girl|jewelry|love|organic|poker|porn|sex|teen|video|webcam) ) {
    return 405;
Jesper is the author of this solution article.

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