# Valve Source Engine

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Our UDP Valve Source Engine filter is activated by default, covering the port range 27000-28000. Only Source Engine-specific traffic is permitted within this range.\
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All custom modded server require an [FastDL](https://developer.valvesoftware.com/wiki/FastDL) configuration, otherwise the download of the custom content will be slow due to the UDP ratelimits.


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# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.packets-decreaser.net/ddos-protection/layer-4/gamefilters/valve-source-engine.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.