..  _introduction:

============
Introduction
============

Every facet, page and sort order of an EXT:solr search page is a distinct URL
such as ``/search?tx_solr[q]=foo&tx_solr[filter][0]=type:pages&tx_solr[page]=2``.
Crawlers follow these links and, worse, generate new combinations on their
own. Each combination misses the page cache and costs a Solr query, so a
single bot can keep both TYPO3 and Solr busy.

Solr Shield takes the ``tx_solr`` parameters out of the public surface:

*   Links generated by EXT:solr and by ``typolink()`` carry one opaque ``_ss``
    parameter instead of ``tx_solr[…]``.
*   Search forms are rewritten so their fields are no longer named
    ``tx_solr[…]``, and they get a hidden ``_ss`` field.
*   Requests that carry ``tx_solr`` parameters without a valid ``_ss`` are
    rejected, and so are requests to the suggest endpoint.

All of this happens on the server and needs neither JavaScript nor changes to
your Solr templates.

..  _introduction-bot-detection:

Bot detection
=============

An optional second layer rejects headless and scripted clients. A small
script records how the visitor interacts with the page and sends a summary
with every search, which the server scores. See
:ref:`how-it-works-bot-detection`.