> ## Documentation Index
> Fetch the complete documentation index at: https://docs.apinizer.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Filter Rules

> You can make filters ready and selectable in API Gateways by defining filters globally. You can provide content control-based defense against API/Web Service attacks and create custom filters with regular expressions.

<Info>
  Filters are policies that ensure security with **Content Control**-based defense against API/Web Service attacks. If the filter/filters you have defined are found in the header, parameter and message content (body) of requests coming from clients, they will be blocked or deleted by Apinizer. Apinizer offers API developers (API Developer) two different options for blocking or deleting the request.

  There are 17 default filters available in the Apinizer Platform and commonly used in the API world:
</Info>

* ASCII Control Character
* SQL Delete Attack
* SQL Drop Table Attack
* SQL Insert Attack
* SQL Server Shutdown Attack
* SQL Update Attack
* XML Processing Attack
* XPath (Abbreviated Syntax) Insertion Attack
* XPath (Expanded Syntax) Insertion Attack
* ASCII Control Characters Except Line Feed and Carriage Return
* Content Longer Than 1024 Chars
* DOCTYPE DTD Reference
* Java Exception Information Leakage
* JavaScript Injection Attack
* OR Attack
* Printf Format String Insertion Attack
* Server Side Include Insertion Attack

In addition to the above, you can write your own **Regular Expressions**.

You cannot edit and delete those added by Apinizer by default.

## Creating a New Filter

Click the **+New** button from the **Management → System Settings → Predefined Values → Filters** screen.

**An image containing Filter creation settings is shown below:**

<img src="https://mintcdn.com/apinizer/7GjNnO8hRuQ2Ils8/images/yonetici/filter.png?fit=max&auto=format&n=7GjNnO8hRuQ2Ils8&q=85&s=a495145f9c444332dd6a5454d04dd1b5" alt="Creating Filter" width="1000" height="600" data-path="images/yonetici/filter.png" />

The fields used for Filter creation configuration are shown in the table below.

| Field                                     | Description                                        |
| ----------------------------------------- | -------------------------------------------------- |
| Filter Name *(Filter Name)*               | Field where the filter definition name is entered. |
| Regular Expression *(Regular Expression)* | Field where the regular expression is entered.     |