> For the complete documentation index, see [llms.txt](https://docs.link11.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.link11.com/product-guides/web-ddos/interface/asn-blocking.md).

# ASN Blocking

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Users will have to choose an algorithm in the [WebDDoS Edit Instance / DDoS Mitigation settings](/product-guides/web-ddos/interface/instances/ddos-mitigation.md#asn-blocking-algorithm).
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<figure><img src="/files/ay8S3ngGoNcXhjV1Evkr" alt=""><figcaption></figcaption></figure>

ASN Blocking or Autonomous System Number Blocking can be used to block traffic from an entire AS. This technique can be useful for mitigating DDoS attacks that originate from a specific AS or network. For example, some AS ranges are known to generate high levels of malicious traffic, and may be blocked as a precaution against scanning attempts.

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**Note:**

An ASN is a unique number that is assigned to an AS by a regional Internet registry (RIR).
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## **Add ASN to Blocklist**

To add a new ASN to the Blocklist, search for the number or name of the organization you wish to block.

<figure><img src="/files/wWl2C0Nkh5DXrtLx6alt" alt=""><figcaption></figcaption></figure>

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