searxng/filtron.rst at 506169f312735301c1eb3ca8d10dd715298087b3

 .. _searxng filtron:
 ==========================
 How to protect an instance
 ==========================
 .. sidebar:: further reading
    - :ref:`filtron.sh`
    - :ref:`nginx searxng site`
 .. contents:: Contents
    :depth: 2
    :local:
    :backlinks: entry
 .. _filtron: https://github.com/searxng/filtron
 SearXNG depends on external search services.  To avoid the abuse of these services
 it is advised to limit the number of requests processed by SearXNG.
 An application firewall, filtron_ solves exactly this problem.  Filtron is just
 a middleware between your web server (nginx, apache, ...) and searx, we describe
 such infrastructures in chapter: :ref:`architecture`.
 filtron & go
 ============
 .. _Go: https://golang.org/
 .. _filtron README: https://github.com/searxng/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:
 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": "missing Accept-Language",
                     "filters": ["!Header:Accept-Language"],
                     "limit": "<max-request-number-in-interval (int)>",
                     "stop": true,
                     "actions": [
                         {"name":"log"},
                         {"name": "block",
                          "params": {"message": "Rate limit exceeded"}}
                     ]
                 },
                 {
                     "name": "suspiciously Connection=close header",
                     "filters": ["Header:Connection=close"],
                     "limit": "<max-request-number-in-interval (int)>",
                     "stop": true,
                     "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",
                     "filters": [
                         "Param:format=(csv|json|rss)"
                     ],
                     "interval": "<time-interval-in-sec (int)>",
                     "limit": "<max-request-number-in-interval (int)>",
                     "stop": true,
                     "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
 =============================
 .. sidebar:: further reading
    - :ref:`filtron.sh overview`
    - :ref:`installation nginx`
    - :ref:`installation apache`
 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
    # https://example.org/searx
    location /searx {
        proxy_pass         http://127.0.0.1:4004/;
        proxy_set_header   Host             $host;
        proxy_set_header   Connection       $http_connection;
        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_set_header   X-Script-Name    /searx;
    }
    location /searx/static {
        /usr/local/searx/searx-src/searx/static;
    }
 Requests are coming from port 4004 going through filtron and then forwarded to
 port 8888 where a SearXNG is being run. For a complete setup see: :ref:`nginx
 searxng site`.