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searxng/docs/admin/filtron.rst
2016-10-30 01:01:22 +02:00

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How to protect an instance
==========================
Searx depens on external search services. To avoid the abuse of these services it is advised to limit the number of requests processed by searx.
An application firewall, ``filtron`` solves exactly this problem. Information on how to install it can be found at the `project page of filtron <https://github.com/asciimoo/filtron>`__.
Sample configuration of filtron
-------------------------------
An example configuration can be find below. This configuration limits the access of
* scripts or applications (roboagent limit)
* webcrawlers (botlimit)
* IPs which send too many requests (IP limit)
* too many json, csv, etc. requests (rss/json limit)
* the same UserAgent of if too many requests (useragent limit)
.. code:: json
[
{
"name": "search request",
"filters": ["Param:q", "Path=^(/|/search)$"],
"interval": <time-interval-in-sec>,
"limit": <max-request-number-in-interval>,
"subrules": [
{
"name": "roboagent limit",
"interval": <time-interval-in-sec>,
"limit": <max-request-number-in-interval>,
"filters": ["Header:User-Agent=(curl|cURL|Wget|python-requests|Scrapy|FeedFetcher|Go-http-client)"],
"actions": [
{"name": "block",
"params": {"message": "Rate limit exceeded"}}
]
},
{
"name": "botlimit",
"limit": 0,
"stop": true,
"filters": ["Header:User-Agent=(Googlebot|bingbot|Baiduspider|yacybot|YandexMobileBot|YandexBot|Yahoo! Slurp|MJ12bot|AhrefsBot|archive.org_bot|msnbot|MJ12bot|SeznamBot|linkdexbot|Netvibes|SMTBot|zgrab|James BOT)"],
"actions": [
{"name": "block",
"params": {"message": "Rate limit exceeded"}}
]
},
{
"name": "IP limit",
"interval": <time-interval-in-sec>,
"limit": <max-request-number-in-interval>,
"stop": true,
"aggregations": ["Header:X-Forwarded-For"],
"actions": [
{"name": "block",
"params": {"message": "Rate limit exceeded"}}
]
},
{
"name": "rss/json limit",
"interval": <time-interval-in-sec>,
"limit": <max-request-number-in-interval>,
"stop": true,
"filters": ["Param:format=(csv|json|rss)"],
"actions": [
{"name": "block",
"params": {"message": "Rate limit exceeded"}}
]
},
{
"name": "useragent limit",
"interval": <time-interval-in-sec>,
"limit": <max-request-number-in-interval>,
"aggregations": ["Header:User-Agent"],
"actions": [
{"name": "block",
"params": {"message": "Rate limit exceeded"}}
]
}
]
}
]
Route request through filtron
-----------------------------
Filtron can be started using the following command:
.. code:: bash
$ filtron -rules rules.json
It listens on 127.0.0.1:4004 and forwards filtered requests to 127.0.0.1:8888 by default.
Use it along with ``nginx`` with the following example configuration.
.. code:: bash
location / {
proxy_set_header Host $http_host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Scheme $scheme;
proxy_pass http://127.0.0.1:4004/;
}
Requests are coming from port 4004 going through filtron and then forwarded to port 8888 where a searx is being run.