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Barracuda Web Application Firewall

Autonomous System Number (ASN)

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An Autonomous System (AS) is a set of Internet Protocol (IP) prefixes of a network or a collection of networks with a defined routing policy. These IP prefixes are managed and controlled by a single entity or an organization. A unique Autonomous System Number (ASN) is assigned to each AS, and network operators use the ASNs to exchange routing information with other organizations and Internet Service Providers (ISPs).

You can add ASNs to Autonomous System Numbers (ASNs) groups on the WEBSITES > IP Reputation page, Add ASN Group section. Multiple ASN groups can be created with one or more ASNs. An ASN can be included in multiple ASN groups. After an ASN group is created, it can be associated with the service(s) to block requests from the ASNs listed in the ASN group.

  • Maximum of 4000 ASNs can be added to an ASN group.
  • An ASN can be associated with maximum of 16 ASN groups.
  • The ASN feature is applicable only at the Application layer IP Reputation.


When an ASN group is associated with a service, and if a client sends a request to the service, the Barracuda WAF uses the client IP address and matches with the Barracuda IP reputation database to get the ASN number of the client. The Barracuda WAF checks if the ASN number is listed in the ASN group associated with the service. If it is present, the request is blocked.

To add an ASN group, do the following:

  1. Go to the WEBSITES > IP Reputation page, ASN Groups section.
  2. Click Add ASN Group and specify values for the following:
    1. ASN Group Name - Enter a name for the ASN group. 
    2. ASN Groups - Enter the ASN group name.
      1. ASN Name: Type the AS organization name and the list of AS organizations with their respective AS number displayed. Select the ASN from the available list.
      2. ASN Code: An AS number is auto-populated when the AS organization is selected from the list.
  3. Click Save.
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