searxng/filtron.rst at baf1ffd1fa4923f3bd105f0d8daac4a9527bdc50

 .. _searx filtron:
 ==========================
 How to protect an instance
 ==========================
 .. sidebar:: further reading
    - :ref:`filtron.sh`
    - :ref:`nginx searx site`
 .. contents:: Contents
    :depth: 2
    :local:
    :backlinks: entry
 .. _filtron: https://github.com/asciimoo/filtron
 Searx depends 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.  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`.
 Sample configuration of filtron
 ===============================
 .. sidebar:: Tooling box
    - :origin:`/etc/filtron/rules.json <utils/templates/etc/filtron/rules.json>`
 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 (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": "log"},
 	     { "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": "log"},
 	     { "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": "log"},
 	     { "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": "log"},
 	     { "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": "log"},
 	     { "name": "block",
 	       "params": {
 		 "message": "Rate limit exceeded"
 	       }
 	     }
 	   ]
 	 }
        ]
      }
    ]
 .. _filtron route request:
 Route request through filtron
 =============================
 Filtron can be started using the following command:
 .. code:: sh
    $ 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:: nginx
    location / {
        proxy_pass         http://127.0.0.1:4004/;
        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;
    }
 Requests are coming from port 4004 going through filtron and then forwarded to
 port 8888 where a searx is being run. For a complete setup see: :ref:`nginx
 searx site`.