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diff --git a/searx/botdetection/limiter.py b/searx/botdetection/limiter.py
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+# SPDX-License-Identifier: AGPL-3.0-or-later
+# lint: pylint
+""".. _limiter src:
+
+Limiter
+=======
+
+.. sidebar:: info
+
+   The limiter requires a :ref:`Redis <settings redis>` database.
+
+Bot protection / IP rate limitation.  The intention of rate limitation is to
+limit suspicious requests from an IP.  The motivation behind this is the fact
+that SearXNG passes through requests from bots and is thus classified as a bot
+itself.  As a result, the SearXNG engine then receives a CAPTCHA or is blocked
+by the search engine (the origin) in some other way.
+
+To avoid blocking, the requests from bots to SearXNG must also be blocked, this
+is the task of the limiter.  To perform this task, the limiter uses the methods
+from the :py:obj:`searx.botdetection`.
+
+To enable the limiter activate:
+
+.. code:: yaml
+
+   server:
+     ...
+     limiter: true  # rate limit the number of request on the instance, block some bots
+
+and set the redis-url connection. Check the value, it depends on your redis DB
+(see :ref:`settings redis`), by example:
+
+.. code:: yaml
+
+   redis:
+     url: unix:///usr/local/searxng-redis/run/redis.sock?db=0
+
+"""
+
+from typing import Optional, Tuple
+import flask
+
+from searx.botdetection import (
+    http_accept,
+    http_accept_encoding,
+    http_accept_language,
+    http_connection,
+    http_user_agent,
+    ip_limit,
+)
+
+
+def filter_request(request: flask.Request) -> Optional[Tuple[int, str]]:
+
+    if request.path == '/healthz':
+        return None
+
+    for func in [
+        http_user_agent,
+    ]:
+        val = func.filter_request(request)
+        if val is not None:
+            return val
+
+    if request.path == '/search':
+
+        for func in [
+            http_accept,
+            http_accept_encoding,
+            http_accept_language,
+            http_connection,
+            http_user_agent,
+            ip_limit,
+        ]:
+            val = func.filter_request(request)
+            if val is not None:
+                return val
+
+    return None