searxng/docs/admin/filtron.rst

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.. _searx_filtron:
==========================
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How to protect an instance
==========================
.. sidebar:: further reading
- :ref:`filtron.sh`
.. contents:: Contents
:depth: 2
:local:
:backlinks: entry
.. _filtron: https://github.com/asciimoo/filtron
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.
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An application firewall, filtron_ solves exactly this problem. Filtron is just
a middleware between your web server (nginx, apache, ...) and searx, we describe
such infratructures in chapter: :ref:`architecture`.
filtron & go
============
.. _Go: https://golang.org/
.. _filtron README: https://github.com/asciimoo/filtron/blob/master/README.md
Filtron needs Go_ installed. If Go_ is preinstalled, filtron_ is simply
installed by ``go get`` package management (see `filtron README`_). If you use
filtron as middleware, a more isolated setup is recommended. To simplify such
an installation and the maintenance of, use our script :ref:`filtron.sh`.
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Sample configuration of filtron
===============================
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An example configuration can be find below. This configuration limits the access
of:
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- 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)
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.. code:: json
[{
"name":"search request",
"filters":[
"Param:q",
"Path=^(/|/search)$"
],
"interval":"<time-interval-in-sec (int)>",
"limit":"<max-request-number-in-interval (int)>",
"subrules":[
{
"name":"roboagent limit",
"interval":"<time-interval-in-sec (int)>",
"limit":"<max-request-number-in-interval (int)>",
"filters":[
"Header:User-Agent=(curl|cURL|Wget|python-requests|Scrapy|FeedFetcher|Go-http-client)"
],
"actions":[
{
"name":"block",
"params":{
"message":"Rate limit exceeded"
}
}
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]
},
{
"name":"botlimit",
"limit":0,
"stop":true,
"filters":[
"Header:User-Agent=(Googlebot|bingbot|Baiduspider|yacybot|YandexMobileBot|YandexBot|Yahoo! Slurp|MJ12bot|AhrefsBot|archive.org_bot|msnbot|MJ12bot|SeznamBot|linkdexbot|Netvibes|SMTBot|zgrab|James BOT)"
],
"actions":[
{
"name":"block",
"params":{
"message":"Rate limit exceeded"
}
}
]
},
{
"name":"IP limit",
"interval":"<time-interval-in-sec (int)>",
"limit":"<max-request-number-in-interval (int)>",
"stop":true,
"aggregations":[
"Header:X-Forwarded-For"
],
"actions":[
{
"name":"block",
"params":{
"message":"Rate limit exceeded"
}
}
]
},
{
"name":"rss/json limit",
"interval":"<time-interval-in-sec (int)>",
"limit":"<max-request-number-in-interval (int)>",
"stop":true,
"filters":[
"Param:format=(csv|json|rss)"
],
"actions":[
{
"name":"block",
"params":{
"message":"Rate limit exceeded"
}
}
]
},
{
"name":"useragent limit",
"interval":"<time-interval-in-sec (int)>",
"limit":"<max-request-number-in-interval (int)>",
"aggregations":[
"Header:User-Agent"
],
"actions":[
{
"name":"block",
"params":{
"message":"Rate limit exceeded"
}
}
]
}
]
}]
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Route request through filtron
=============================
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Filtron can be started using the following command:
.. code:: sh
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$ filtron -rules rules.json
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It listens on ``127.0.0.1:4004`` and forwards filtered requests to
``127.0.0.1:8888`` by default.
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Use it along with ``nginx`` with the following example configuration.
.. code:: nginx
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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/;
}
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Requests are coming from port 4004 going through filtron and then forwarded to
port 8888 where a searx is being run.