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